The Entity Attestation Token (EAT)Security Theory LLClgl@securitytheory.comQualcomm Technologies Inc.5775 Morehouse DriveSan DiegoCaliforniaUSA+1 858 651 7200mandyam@qti.qualcomm.comQualcomm Technologies Inc.279 Farnborough RoadFarnboroughGU14 7LSUnited Kingdom+44 1252 363189jodonogh@qti.qualcomm.com
Internet
RATS Working Groupsigning attestation cborAn Entity Attestation Token (EAT) provides an attested claims set
that describes state and characteristics of an entity,
a device like a phone, IoT device, network equipment or such. This claims set is used by a
relying party, server or service to determine how much it wishes to trust the entity.An EAT is either a CBOR Web Token (CWT) or JSON Web Token (JWT) with attestation-oriented
claims. To a large degree, all this document does is extend
CWT and JWT.EAT provides the definition of a base set of claims that can be made about an entity, a device, some software and/or some hardware.
This claims set is received by a relying party who uses it to decide if and how it will interact with the remote entity.
It may choose to not trust the entity and not interact with it.
It may choose to trust it.
It may partially trust it, for example allowing monetary transactions only up to a limit.EAT defines the encoding of the claims set in CBOR and JSON .
EAT is an extension to CBOR Web Token (CWT) and JSON Web Token (JWT) .The claims set is secured in transit with the same mechanisms used by CWT and JWT, in particular CBOR Object Signing and Encryption (COSE) and JSON Object Signing
and Encryption (JOSE) .
Authenticity and integrity protection must always be provided.
Privacy (encryption) may additionally be provided.
The key material used to sign and encrypt is specifically created and provisioned for the purpose of attestation.
It is the use of this key material that make the claims set “attested” rather than just some parameters sent to the relying party by the device.EAT is focused on authenticating, identifying and characterizing implementations where implementations are devices, chips, hardware, software and such.
This is distinct from protocols like TLS that authenticate and identify servers and services.
It is equally distinct from protocols like SASL that authenticate and identify persons.The notion of attestation is large, ranging over a broad variety of use cases and security levels.
Here are a few examples of claims:Make and model of manufactured consumer deviceMake and model of a chip or processor, particularly for a security-oriented chipIdentification and measurement of the software running on a deviceConfiguration and state of a deviceEnvironmental characteristics of a device like its GPS locationFormal certifications receivedEAT also supports nesting of sets of claims and EAT tokens for use with complex composite devices.This document uses the terminology and main operational model defined in .
In particular, it can be used for RATS Attestation Evidence and Attestation Results.The document uses the term “entity” to refer to the target of the attestation token.
The claims defined in this document are claims about an entity.An entity is an implementation in hardware, software or both.An entity is the same as the Attester Target Environment defined in RATS Architecture.An entity also corresponds to a “system component” as defined in the Internet Security Glossary .
That glossary also defines “entity” and “system entity” as something that may be a person or organization as well as a system component.
Here “entity” never refers to a person or organization.An entity is never a server or a service.An entity may be the whole device or it may be a subsystem, a subsystem of a subsystem and so on.
EAT allows claims to be organized into submodules, nested EATs and so on. See .
The entity to which a claim applies is the submodule in which it appears, or to the top-level entity if it doesn’t appear in a submodule.Some examples of entities:A Secure ElementA TEEA card in a network routerA network router, perhaps with each card in the router a submoduleAn IoT deviceAn individual processAn app on a smartphoneA smartphone with many submodules for its many subsystemsA subsystem in a smartphone like the modem or the cameraAn entity may have strong security like defenses against hardware invasive attacks.
It may also have low security, having no special security defenses.
There is no minimum security requirement to be an entity.An EAT is a claims set about an entity based on one of the following:CBOR Web Token (CWT) Unprotected CWT Claims Sets (UCCS) JSON Web Token (JWT) All definitions, requirements, creation and validation procedures, security considerations, IANA registrations and so on from these carry over to EAT.This specification extends those specifications by defining additional claims for attestation.
This specification also describes the notion of a “profile” that can narrow the definition of an EAT, ensure interoperability and fill in details for specific usage scenarios.
This specification also adds some considerations for registration of future EAT-related claims.The identification of a protocol element as an EAT, whether CBOR or JSON encoded, follows the general conventions used by CWT, JWT and UCCS.
Largely this depends on the protocol carrying the EAT.
In some cases it may be by content type (e.g., MIME type).
In other cases it may be through use of CBOR tags.
There is no fixed mechanism across all use cases.This specification adds two more top-level messages:Unprotected JWT Claims Set (UJCS) Detached EAT Bundle (DEB), A DEB is structure to hold a collection of detached claims sets and the EAT that separately provides integrity and authenticity protection for them.
It can be either CBOR or JSON encoded.This document defines Concise Binary Object Representation (CBOR) and Javascript Object Notation (JSON) encoding for an EAT.
All claims in an EAT MUST use the same encoding except where explicitly allowed.
It is explicitly allowed for a nested token to be of a different encoding.
Some claims explicitly contain objects and messages that may use a different encoding than the enclosing EAT.This specification uses Concise Data Definition Language (CDDL) for all definitions.
The implementor interprets the CDDL to come to either the CBOR or JSON encoding.
In the case of JSON, Appendix E of is followed.
Additional rules are given in where Appendix E is insufficient.The CWT and JWT specifications were authored before CDDL was available and did not use CDDL.
This specification includes a CDDL definition of most of what is defined in .
Similarly, this specification includes CDDL for most of what is defined in .The UCCS specification does not include CDDL.
This specification provides CDDL for it.While it is not required that EAT be used with the RATS operational model described in Figure 1 in , or even that it be used for attestation, this document is oriented around that model.To summarize, an Attester generates Attestation Evidence.
Attestation Evidence is a claims set describing various characteristics of an entity.
Attestation Evidence also is usually signed by a key that proves the entity and the evidence it produces are authentic.
The claims set includes a nonce or some other means to provide freshness.
EAT is designed to carry Attestation Evidence.
The Attestation Evidence goes to a Verifier where the signature is verified.
Some of the claims may also be checked against Reference Values.
The Verifier then produces Attestation Results which is also usually a claims set.
EAT is also designed to carry Attestation Results.
The Attestation Results go to the Relying Party which is the ultimate consumer of the Remote Attestation Procedure.
The Relying Party uses the Attestation Results as needed for the use case, perhaps allowing an entity on the network, allowing a financial transaction or such.Note that sometimes the Verifier and Relying Party are not separate and thus there is no need for a protocol to carry Attestation Results.Any claim defined in this document or in the IANA CWT or JWT registry may be used in Attestation Evidence or Attestation Results.Many claims in Attestation Evidence simply will pass through the Verifier to the Relying Party without modification.
They will be verified as authentic from the entity by the Verifier just through normal verification of the Attester’s signature.
The UEID, , and Location, , are examples of claims that may be passed through.Some claims in Attestation Evidence will be verified by the Verifier by comparison to Reference Values.
These claims will not likely be conveyed to the Relying Party.
Instead, some claim indicating they were checked may be added to the Attestation Results or it may be tacitly known that the Verifier always does this check.
For example, the Verifier receives the Software Evidence claim, , compares it to Reference Values and conveys the results to the Relying Party in a Software Measurement Results Claim, .In some cases the Verifier may provide privacy-preserving functionality by stripping or modifying claims that do not posses sufficient privacy-preserving characteristics.
For example, the data in the Location claim, , may be modified to have a precision of a few kilometers rather than a few meters.The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”,
“SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “NOT RECOMMENDED”, “MAY”, and
“OPTIONAL” in this document are to be interpreted as described in
BCP 14 when, and only when, they appear in all
capitals, as shown here.This document reuses terminology from JWT and CWT .
A piece of information asserted about a subject. A claim is represented as pair with a value and either a name or key to identify it.
A unique text string that identifies the claim. It is used as the claim name for JSON encoding.
The CBOR map key used to identify a claim.
The value portion of the claim. A claim value can be any CBOR data item or JSON value.
The CBOR map or JSON object that contains the claims conveyed by the CWT or JWT.This document reuses terminology from RATS Architecure
A role performed by an entity (typically a device) whose Evidence must be appraised in order to infer the extent to which the Attester is considered trustworthy, such as when deciding whether it is authorized to perform some operation.
A role that appraises the validity of Attestation Evidence about an Attester and produces Attestation Results to be used by a Relying Party.
A role that depends on the validity of information about an Attester, for purposes of reliably applying application specific actions. Compare /relying party/ in .
A Claims Set generated by an Attester to be appraised by a Verifier. Attestation Evidence may include configuration data, measurements, telemetry, or inferences.
The output generated by a Verifier, typically including information about an Attester, where the Verifier vouches for the validity of the results
A set of values against which values of Claims can be compared as part of applying an Appraisal Policy for Attestation Evidence. Reference Values are sometimes referred to in other documents as known-good values, golden measurements, or nominal values, although those terms typically assume comparison for equality, whereas here Reference Values might be more general and be used in any sort of comparison.This section describes new claims defined for attestation that are to be added to the CWT and JWT IANA registries.This section also describes how several extant CWT and JWT claims apply in EAT.CDDL, along with a text description, is used to define each claim
independent of encoding. Each claim is defined as a CDDL group.
In on encoding, the CDDL groups turn into CBOR map entries and JSON name/value pairs.Each claim described has a unique text string and integer that identifies it.
CBOR encoded tokens MUST use only the integer for Claim Keys.
JSON encoded tokens MUST use only the text string for Claim Names.CWT defines the “cti” claim. JWT defines the “jti” claim. These are
equivalent to each other in EAT and carry a unique token identifier as
they do in JWT and CWT. They may be used to defend against re use of
the token but are distinct from the nonce that is used by the Relying
Party to guarantee freshness and defend against replay.The “iat” claim defined in CWT and JWT is used to indicate the
date-of-creation of the token, the time at which the claims are
collected and the token is composed and signed.The data for some claims may be held or cached for some period of
time before the token is created. This period may be long, even
days. Examples are measurements taken at boot or a geographic
position fix taken the last time a satellite signal was received.
There are individual timestamps associated with these claims to
indicate their age is older than the “iat” timestamp.CWT allows the use floating-point for this claim. EAT disallows
the use of floating-point. An EAT token MUST NOT contain an iat claim in
float-point format. Any recipient of a token with a floating-point
format iat claim MUST consider it an error. A 64-bit integer
representation of epoch time can represent a range of +/- 500 billion
years, so the only point of a floating-point timestamp is to
have precession greater than one second. This is not needed for EAT.All EATs should have a nonce to prevent replay attacks. The nonce is
generated by the Relying Party, the end consumer of the token. It is
conveyed to the entity over whatever transport is in use before the
token is generated and then included in the token as the nonce claim.This documents the nonce claim for registration in the IANA CWT
claims registry. This is equivalent to the JWT nonce claim that is
already registered.The nonce must be at least 8 bytes (64 bits) long as fewer bytes are unlikely
to be secure. A maximum of 64 bytes is set to limit the memory
a constrained implementation uses. This size range is not set
for the already-registered JWT nonce, but it should follow
this size recommendation when used in an EAT.Multiple nonces are allowed to accommodate multistage verification
and consumption. nonce-type / [ 2* nonce-type ])
nonce-type = bstr .size (8..64)
]]>A UEID identifies an individual manufactured entity like a
mobile phone, a water meter, a Bluetooth speaker or a networked
security camera. It may identify the entire entity or a submodule.
It does not identify types, models or classes of
entities. It is akin to a serial number, though it does not have to be
sequential.UEIDs MUST be universally and globally unique across manufacturers
and countries. UEIDs MUST also be unique across protocols and systems,
as tokens are intended to be embedded in many different protocols and
systems. No two products anywhere, even in completely different
industries made by two different manufacturers in two different
countries should have the same UEID (if they are not global and
universal in this way, then Relying Parties receiving them will have
to track other characteristics of the entity to keep entities distinct
between manufacturers).There are privacy considerations for UEIDs. See .The UEID is permanent. It MUST never change for a given entity.A UEID is constructed of a single type byte followed by the bytes that are the identifier.
Several types are allowed to accommodate different industries, different manufacturing processes
and to have an alternative that doesn’t require paying a registration fee.Creation of new types requires a Standards Action .UEIDs are variable length. All implementations MUST be able to receive
UEIDs that are 33 bytes long (1 type byte and 256 bits).
No UEID longer than 33 bytes SHOULD be sent.Type ByteType NameSpecification0x01RANDThis is a 128, 192 or 256-bit random number generated once and stored in the entity. This may be constructed by concatenating enough identifiers to make up an equivalent number of random bits and then feeding the concatenation through a cryptographic hash function. It may also be a cryptographic quality random number generated once at the beginning of the life of the entity and stored. It MUST NOT be smaller than 128 bits. See the length analysis in .0x02IEEE EUIThis uses the IEEE company identification registry. An EUI is either an EUI-48, EUI-60 or EUI-64 and made up of an OUI, OUI-36 or a CID, different registered company identifiers, and some unique per-entity identifier. EUIs are often the same as or similar to MAC addresses. This type includes MAC-48, an obsolete name for EUI-48. (Note that while entities with multiple network interfaces may have multiple MAC addresses, there is only one UEID for an entity) , .0x03IMEIThis is a 14-digit identifier consisting of an 8-digit Type Allocation Code and a 6-digit serial number allocated by the manufacturer, which SHALL be encoded as byte string of length 14 with each byte as the digit’s value (not the ASCII encoding of the digit; the digit 3 encodes as 0x03, not 0x33). The IMEI value encoded SHALL NOT include Luhn checksum or SVN information. See .UEIDs are not designed for direct use by humans (e.g., printing on
the case of a device), so no textual representation is defined.The consumer (the Relying Party) of a UEID MUST treat a UEID as a
completely opaque string of bytes and not make any use of its internal
structure. For example, they should not use the OUI part of a type
0x02 UEID to identify the manufacturer of the entity. Instead, they
should use the OEMID claim. See . The reasons for
this are:UEIDs types may vary freely from one manufacturer to the next.New types of UEIDs may be created. For example, a type 0x07 UEID may
be created based on some other manufacturer registration scheme.Entity manufacturers are allowed to change from one type of UEID to
another anytime they want. For example, they may find they can
optimize their manufacturing by switching from type 0x01 to type
0x02 or vice versa. The essential requirement on the manufacturer is
that UEIDs be universally unique.A Device Identifier URN is registered for UEIDs. See . ueid-type)
ueid-type = bstr .size (7..33)
]]>An SEUID is of the same format as a UEID, but it MAY change to a different value on device life-cycle events.
Examples of these events are change of ownership, factory reset and on-boarding into an IoT device management system.
An entity MAY have both a UEID and SUEIDs, neither, one or the other.There MAY be multiple SUEIDs.
Each one has a text string label the purpose of which is to distinguish it from others in the token.
The label MAY name the purpose, application or type of the SUEID.
Typically, there will be few SUEDs so there is no need for a formal labeling mechanism like a registry.
The EAT profile MAY describe how SUEIDs should be labeled.
If there is only one SUEID, the claim remains a map and there still must be a label.
For example, the label for the SUEID used by FIDO Onboarding Protocol could simply be “FDO”.There are privacy considerations for SUEIDs. See .A Device Indentifier URN is registered for SUEIDs. See . sueids-type)
sueids-type = {
+ tstr => ueid-type
}
]]>This claim identifies the Original Equipment Manufacturer (OEM) of the hardware.
Any of the three forms described below MAY be used at the convenience of the claim sender.
The receiver of this claim MUST be able to handle all three forms.The random number based OEMID MUST always 16 bytes (128 bits).The OEM MAY create their own ID by using a cryptographic-quality random number generator.
They would perform this only once in the life of the company to generate the single ID for said company.
They would use that same ID in every entity they make.
This uniquely identifies the OEM on a statistical basis and is large enough should there be ten billion companies.The OEM MAY also use a hash function like SHA-256 and truncate the output to 128 bits.
The input to the hash should be somethings that have at least 96 bits of entropy, but preferably 128 bits of entropy.
The input to the hash MAY be something whose uniqueness is managed by a central registry like a domain name.In JSON format tokens this MUST be base64url encoded.The IEEE operates a global registry for MAC addresses and company IDs.
This claim uses that database to identify OEMs. The contents of the
claim may be either an IEEE MA-L, MA-M, MA-S or an IEEE CID
. An MA-L, formerly known as an OUI, is a 24-bit value
used as the first half of a MAC address. MA-M similarly is a 28-bit
value uses as the first part of a MAC address, and MA-S, formerly
known as OUI-36, a 36-bit value. Many companies already have purchased
one of these. A CID is also a 24-bit value from the same space as an
MA-L, but not for use as a MAC address. IEEE has published Guidelines
for Use of EUI, OUI, and CID and provides a lookup
service .Companies that have more than one of these IDs or MAC address blocks
SHOULD select one and prefer that for all their entities.Commonly, these are expressed in Hexadecimal Representation as described in
. It is also called the Canonical format. When this claim is
encoded the order of bytes in the bstr are the same as the order in the
Hexadecimal Representation. For example, an MA-L like “AC-DE-48” would
be encoded in 3 bytes with values 0xAC, 0xDE, 0x48.This format is always 3 bytes in size in CBOR.In JSON format tokens, this MUST be base64url encoded and always 4 bytes.IANA maintains a integer-based company registry called the Private Enterprise Number (PEN) .PENs are often used to create an OID.
That is not the case here.
They are used only as an integer.In CBOR this value MUST be encoded as a major type 0 integer and is typically 3 bytes.
In JSON, this value MUST be encoded as a number.
oemid-random / oemid-ieee / oemid-pen
)
]]>This claim differentiates hardware models, products and variants manufactured by a particular OEM, the one identified by OEM ID in .This claim must be unique so as to differentiate the models and products for the OEM ID.
This claim does not have to be globally unique, but it can be.
A receiver of this claim MUST not assume it is globally unique.
To globally identify a particular product, the receiver should concatenate the OEM ID and this claim.The granularity of the model identification is for each OEM to decide.
It may be very granular, perhaps including some version information.
It may be very general, perhaps only indicating top-level products.The purpose of this claim is to identify models within protocols, not for human-readable descriptions.
The format and encoding of this claim should not be human-readable to discourage use other than in protocols.
If this claim is to be derived from an already-in-use human-readable identifier, it can be run through a hash function.There is no minimum length so that an OEM with a very small number of models can use a one-byte encoding.
The maximum length is 32 bytes.
All receivers of this claim MUST be able to receive this maximum size.The receiver of this claim MUST treat it as a completely opaque string of bytes, even if there is some apparent naming or structure.
The OEM is free to alter the internal structure of these bytes as long as the claim continues to uniquely identify its models. hardware-model-type
)
]]>The hardware version is a text string the format of which is set by each manufacturer.
The structure and sorting order of this text string can be specified using the version-scheme item from CoSWID .
It is useful to know how to sort versions so the newer can be distinguished from the older.The hardware version can also be given by a 13-digit .
A new CoSWID version scheme is registered with IANA by this document in .
An EAN-13 is also known as an International Article Number or most commonly as a bar code. hardware-version-type
)
hardware-version-type = [
version: tstr,
scheme: $version-scheme
]
]]>This is a free-form text claim for the name of the software for the entity or submodule.
A CoSWID manifest or other type of manifest can be used instead if this claim is to limited to correctly characterize the SW for the entity or submodule. tstr )
]]>This makes use of the CoSWID version scheme data type to give a simple version for the software.
A full CoSWID manifest or other type of manifest can be instead if this is too simple. sw-version-type)
sw-version-type = [
version: tstr,
scheme: $version-scheme ; As defined by CoSWID
]
]]>This claim characterizes the entity’s
ability to defend against attacks aimed at capturing the signing
key, forging claims and at forging EATs. This is by
defining four security levels.This claim describes the security environment and countermeasures
available on the entity where the attestation key
resides and the claims originate.
There is some expectation that implementor will
protect the attestation signing keys at this level. Otherwise,
the EAT provides no meaningful security assurances.
Entities at this level are not general-purpose
operating environments that host features, such as app download
systems, web browsers and complex applications.
It is akin to the secure-restricted level (see below) without the
security orientation. Examples include a Wi-Fi subsystem,
an IoT camera, or sensor device.
Often these can be considered more secure than unrestricted just because they are much simpler and a smaller attack surface, but this won’t always be the case.
Some unrestricted devices may be implemented in a way that provides poor protection of signing keys.
Entities at this level must meet the criteria defined in Section 4 of FIDO Allowed
Restricted Operating Environments . Examples include TEE’s and
schemes using virtualization-based security.
Security at this level is aimed at defending against large-scale
network/remote attacks against the entity.
Entities at this level must include substantial defense
against physical or electrical attacks against the entity itself.
It is assumed the potential attacker has captured the entity and can
disassemble it. Examples include TPMs and Secure Elements.The entity should claim the highest security level it achieves and no higher.
This set is not extensible so as to provide a common interoperable description of security level to the Relying Party.
If a particular use case considers this claim to be inadequate, it can define its own proprietary claim.
It may consider including both this claim as a coarse indication of security and its own proprietary claim as a refined indication.This claim is not intended as a replacement for a formal
security certification scheme, such as those based on FIPS 140
or those based on Common Criteria .
See .
security-level-cbor-type /
security-level-json-type
)
security-level-cbor-type = &(
unrestricted: 1,
restricted: 2,
secure-restricted: 3,
hardware: 4
)
security-level-json-type =
"unrestricted" /
"restricted" /
"secure-restricted" /
"hardware"
]]>The value of true indicates secure boot is enabled. Secure boot is
considered enabled when the firmware and operating
system, are under control of the manufacturer of the entity identified in the
OEMID claim described in .
Control by the manufacturer of the firmware and the operating system may be by it being in ROM, being cryptographically authenticated, a combination of the two or similar. bool)
]]>This applies to entity-wide or submodule-wide debug facilities of the
entity like JTAG and diagnostic hardware built into
chips. It applies to any software debug facilities related to root,
operating system or privileged software that allow system-wide memory
inspection, tracing or modification of non-system software like user
mode applications.This characterization assumes that debug facilities can be enabled and
disabled in a dynamic way or be disabled in some permanent way such
that no enabling is possible. An example of dynamic enabling is one
where some authentication is required to enable debugging. An example
of permanent disabling is blowing a hardware fuse in a chip. The specific
type of the mechanism is not taken into account. For example, it does
not matter if authentication is by a global password or by per-entity
public keys.As with all claims, the absence of the debug level claim means it is not reported.
A conservative interpretation might assume the enabled state.This claim is not extensible so as to provide a common interoperable description of debug status.
If a particular implementation considers this claim to be inadequate, it can define its own proprietary claim.
It may consider including both this claim as a coarse indication of debug status and its own proprietary claim as a refined indication.The higher levels of debug disabling requires that all debug disabling
of the levels below it be in effect. Since the lowest level requires
that all of the target’s debug be currently disabled, all other levels
require that too.There is no inheritance of claims from a submodule to a superior
module or vice versa. There is no assumption, requirement or guarantee
that the target of a superior module encompasses the targets of
submodules. Thus, every submodule must explicitly describe its own
debug state. The receiver of an EAT MUST not
assume that debug is turned off in a submodule because there is a claim
indicating it is turned off in a superior module.An entity may have multiple debug
facilities. The use of plural in the description of the states
refers to that, not to any aggregation or inheritance.The architecture of some chips or devices may be such that a debug
facility operates for the whole chip or device. If the EAT for such
a chip includes submodules, then each submodule should independently
report the status of the whole-chip or whole-device debug facility.
This is the only way the receiver can know the debug status
of the submodules since there is no inheritance.If any debug facility, even manufacturer hardware diagnostics, is
currently enabled, then this level must be indicated.This level indicates all debug facilities are currently disabled. It
may be possible to enable them in the future. It may also be
that they were enabled in the past, but they are currently disabled.This level indicates all debug facilities are currently disabled and
have been so since the entity booted/started.This level indicates all non-manufacturer facilities are permanently
disabled such that no end user or developer can enable them. Only
the manufacturer indicated in the OEMID claim can enable them. This
also indicates that all debug facilities are currently disabled and
have been so since boot/start.This level indicates that all debug facilities for the entity are permanently disabled.
debug-status-cbor-type / debug-status-json-type
)
debug-status-cbor-type = &(
enabled: 0,
disabled: 1,
disabled-since-boot: 2,
disabled-permanently: 3,
disabled-fully-and-permanently: 4
)
debug-status-json-type =
"enabled" /
"disabled" /
"disabled-since-boot" /
"disabled-permanently" /
"disabled-fully-and-permanently"
]]>An EAT may include a cryptographic key such as a public key.
The signing of the EAT binds the key to all the other claims in the token.The purpose for inclusion of the key may vary by use case.
For example, the key may be included as part of an IoT device onboarding protocol.
When the FIDO protocol includes a public key in its attestation message, the key represents the binding of a user, device and Relying Party.
This document describes how claims containing keys should be defined for the various use cases.
It does not define specific claims for specific use cases.Keys in CBOR format tokens SHOULD be the COSE_Key format and keys in JSON format tokens SHOULD be the JSON Web Key format .
These two formats support many common key types.
Their use avoids the need to decode other serialization formats.
These two formats can be extended to support further key types through their IANA registries.The general confirmation claim format , may also be used.
It provides key encryption.
It also allows for inclusion by reference through a key ID.
The confirmation claim format may employed in the definition of some new claim for a a particular use case.When the actual confirmation claim is included in an EAT, this document associates no use case semantics other than proof of possession.
Different EAT use cases may choose to associate further semantics.
The key in the confirmation claim MUST be protected in the same way as the key used to sign the EAT.
That is, the same, equivalent or better hardware defenses, access controls, key generation and such must be used.The location claim gives the location of the entity from which the attestation originates.
It is derived from the W3C Geolocation API .
The latitude, longitude, altitude and accuracy must conform to .
The altitude is in meters above the ellipsoid.
The two accuracy values are positive numbers in meters.
The heading is in degrees relative to true north.
If the entity is stationary, the heading is NaN (floating-point not-a-number).
The speed is the horizontal component of the entity velocity in meters per second.When encoding floating-point numbers half-precision SHOULD NOT be used.
They usually do not provide enough precision for a geographic location.The location may have been cached for a period of time before token
creation. For example, it might have been minutes or hours or more
since the last contact with a GPS satellite. Either the timestamp or
age data item can be used to quantify the cached period. The timestamp
data item is preferred as it a non-relative time.The age data item can be used when the entity doesn’t know what time
it is either because it doesn’t have a clock or it isn’t set. The
entity MUST still have a “ticker” that can measure a time
interval. The age is the interval between acquisition of the location
data and token creation.See location-related privacy considerations in . location-type)
location-type = {
latitude => number,
longitude => number,
? altitude => number,
? accuracy => number,
? altitude-accuracy => number,
? heading => number,
? speed => number,
? timestamp => ~time-int,
? age => uint
}
latitude = 1 / "latitude"
longitude = 2 / "longitude"
altitude = 3 / "altitude"
accuracy = 4 / "accuracy"
altitude-accuracy = 5 / "altitude-accuracy"
heading = 6 / "heading"
speed = 7 / "speed"
timestamp = 8 / "timestamp"
age = 9 / "age"
]]>The “uptime” claim MUST contain a value that represents the number of
seconds that have elapsed since the entity or submod was last booted. uint)
]]>The “odometer” claim contains a value that represents the number of
times the entity or submod has been booted. Support for this claim
requires a persistent storage on the device. uint)
]]>The Boot Seed claim MUST contain a random value created at system boot time that will allow differentiation of reports from different boot sessions.This value is usually public.
It is not a secret and MUST NOT be used for any purpose that a secret seed is needed, such as seeding a random number generator. bytes)
]]>EAT’s may be used in the context of several different applications. The intended-use
claim provides an indication to an EAT consumer about the intended usage
of the token. This claim can be used as a way for an application using EAT to internally distinguish between different ways it uses EAT.
Generic attestation describes an application where the EAT consumer
requires the most up-to-date security assessment of the attesting entity. It
is expected that this is the most commonly-used application of EAT.
Entities that are registering for a new service may be expected to
provide an attestation as part of the registration process. This intended-use
setting indicates that the attestation is not intended for any use but registration.
Entities may be provisioned with different values or settings by an EAT
consumer. Examples include key material or device management trees. The consumer
may require an EAT to assess entity security state of the entity prior to provisioning.
Certification Authorities (CA’s) may require attestations prior to
the issuance of certificates related to keypairs hosted at the entity. An
EAT may be used as part of the certificate signing request (CSR).
An EAT consumer may require an attestation as part of an accompanying
proof-of-possession (PoP) application. More precisely, a PoP transaction is intended
to provide to the recipient cryptographically-verifiable proof that the sender has possession
of a key. This kind of attestation may be necceesary to verify the
security state of the entity storing the private key used in a PoP application.
intended-use-cbor-type / intended-use-json-type
)
intended-use-cbor-type = &(
generic: 1,
registration: 2,
provisioning: 3,
csr: 4,
pop: 5
)
intended-use-json-type =
"generic" /
"registration" /
"provisioning" /
"csr" /
"pop"
]]>See for the detailed description of a profile.A profile is identified by either a URL or an OID.
Typically, the URI will reference a document describing the profile.
An OID is just a unique identifier for the profile.
It may exist anywhere in the OID tree.
There is no requirement that the named document be publicly accessible.
The primary purpose of the profile claim is to uniquely identify the profile even if it is a private profile.The OID is always absolute and never relative.
In CBOR tokens, the OID MUST be encoded according to and the URI according to .
Both are unwrapped and thus not CBOR tags.
In JSON tokens, the OID is a string of the form “X.X.X”, and a URI is a normal URI string.Note that this is named “eat_profile” for JWT and is distinct from the already registered “profile” claim in the JWT claims registry. ~uri / ~oid)
]]>A DLOA (Digital Letter of Approval) is an XML document that describes a certification that an entity has received.
Examples of certifications represented by a DLOA include those issued by Global Platform and those based on Common Criteria.
The DLOA is unspecific to any particular certification type or those issued by any particular organization.This claim is typically issued by a Verifier, not an Attester.
When this claim is issued by a Verifier, it MUST be because the entity has received the certification in the DLOA.This claim MAY contain more than one DLOA.
If multiple DLOAs are present, it MUST be because the entity received all of the certifications.DLOA XML documents are always fetched from a registrar that stores them.
This claim contains several data items used to construct a URL for fetching the DLOA from the particular registrar.This claim MUST be encoded as an array with either two or three elements.
The first element MUST be the URI for the registrar.
The second element MUST be a platform label indicating which platform was certified.
If the DLOA applies to an application, then the third element is added which MUST be an application label.
The method of constructing the registrar URI, platform label and possibly application label is specified in . [ + dloa-type ]
)
dloa-type = [
dloa_registrar: ~uri
dloa_platform_label: text
? dloa_application_label: text
]
]]>This claim contains descriptions of software present on the entity.
These manifests are installed on the entity when the software is installed or are created as part of the installation process.
Installation is anything that adds software to the entity, possibly factory installation, the user installing elective applications and so on.
The defining characteristic is they are created by the software manufacturer.
The purpose of these claims in an EAT is to relay them without modification to the Verifier and possibly to the Relying Party.Some manifests may be signed by their software manufacturer before they are put into this EAT claim.
When such manifests are put into this claim, the manufacturer’s signature SHOULD be included.
For example, the manifest might be a CoSWID signed by the software manufacturer, in which case the full signed CoSWID should be put in this claim.This claim allows multiple formats for the manifest.
For example, the manifest may be a CBOR-format CoSWID, an XML-format SWID or other.
Identification of the type of manifest is always by a CBOR tag.
In many cases, for examples CoSWID, a tag will already be registered with IANA.
If not, a tag MUST be registered.
It can be in the first-come-first-served space which has minimal requirements for registration.The claim is an array of one or more manifests.
To facilitate hand off of the manifest to a decoding library, each manifest is contained in a byte string.
This occurs for CBOR-format manifests as well as non-CBOR format manifests.If a particular manifest type uses CBOR encoding, then the item in the array for it MUST be a byte string that contains a CBOR tag.
The EAT decoder must decode the byte string and then the CBOR within it to find the tag number to identify the type of manifest.
The contents of the byte string is then handed to the particular manifest processor for that type of manifest.
CoSWID and SUIT manifest are examples of this.If a particular manifest type does not use CBOR encoding, then the item in the array for it MUST be a CBOR tag that contains a byte string.
The EAT decoder uses the tag to identify the processor for that type of manifest.
The contents of the tag, the byte string, are handed to the manifest processor.
Note that a byte string is used to contain the manifest whether it is a text based format or not.
An example of this is an XML format ISO/IEC 19770 SWID.It is not possible to describe the above requirements in CDDL, so the type for an individual manifest is any in the CDDL below.
The above text sets the encoding requirement.This claim allows for multiple manifests in one token since multiple software packages are likely to be present.
The multiple manifests MAY be of multiple formats.
In some cases EAT submodules may be used instead of the array structure in this claim for multiple manifests.When the format is used, it MUST be a payload CoSWID, not an evidence CoSWID. manifests-type
)
manifests-type = [+ $$manifest-formats]
coswid-that-is-a-cbor-tag-xx = tagged-coswid
$$manifest-formats /= bytes .cbor coswid-that-is-a-cbor-tag-xx
]]>This claim contains descriptions, lists, evidence or measurements of the software that exists on the entity.
The defining characteristic of this claim is that its contents are created by processes on the entity that inventory, measure or otherwise characterize the software on the entity.
The contents of this claim do not originate from the software manufacturer.This claim uses the same mechanism for identification of the type of the swevidence as is used for the type of the manifest in the manifests claim.
It also uses the same byte string based mechanism for containing the claim and easing the hand off to a processing library.
See the discussion above in the manifests claim.When the format is used, it MUST be evidence CoSWIDs, not payload CoSWIDS. swevidence-type
)
swevidence-type = [+ $$swevidence-formats]
coswid-that-is-a-cbor-tag = tagged-coswid
$$swevidence-formats /= bytes .cbor coswid-that-is-a-cbor-tag
]]>This claims reports the outcome of the comparison of a measurement on some software to the expected Reference Values.
It may report a successful comparison, failed comparison or other.This claim MAY be generated by the Verifier and sent to the Relying Party.
For example, it could be the results of the Verifier comparing the contents of the swevidence claim to Reference Values.This claim MAY also be generated on the entity if the entity has the ability for one subsystem to measure another subsystem.
For example, a TEE might have the ability to measure the software of the rich OS and may have the Reference Values for the rich OS.Within an attestation target or submodule, multiple results can be reported.
For example, it may be desirable to report the results for the kernel and each individual application separately.For each software objective, the following can be reported. TODO: defined objectiveThis is the free-form text name of the verification system or scheme that performed the verification.
There is no official registry of schemes or systems.
It may be the name of a commercial product or such.This roughly characterizes the coverage of the software measurement software.
This corresponds to the attestation target or the submodule.
If all of the indicated target is not covered, the measurement must indicate partial.
Indicates all the software has been verified, for example, all the software in the attestation target or the submodule
Indicates all of and only the firmware
Refers to all of the most-privileged software, for example the Linux kernel
Refers to all of the software used by the root, system or administrative account
Refers to all of the system libraries that are broadly shared and used by applications and such
Some other partial set of the softwareThis describes the result of the measurement and also the comparison to Reference Values.
Indicates that no attempt was made to run the verification
The verification was attempted, but it did not produce a result; perhaps it ran out of memory, the battery died or such
The verification ran to completion, the comparison was completed and did not compare correctly to the Reference Values
The verification ran to completion and all measurements compared correctly to Reference Values
The verification ran to completion and some, but not all, measurements compared correctly to Reference ValuesThis is a free-form text string that describes the objective.
For example, “Linux kernel” or “Facebook App” [ + swresult-type ])
verification-result-cbor-type = &(
verification-not-run: 1,
verification-indeterminate: 2,
verification-failed: 3,
fully-verified: 4,
partially-verified: 5,
)
verification-result-json-type =
"verification-not-run" /
"verification-indeterminate" /
"verification-failed" /
"fully-verified" /
"partially-verified"
verification-objective-cbor-type = &(
all: 1,
firmware: 2,
kernel: 3,
privileged: 4,
system-libs: 5,
partial: 6,
)
verification-objective-json-type =
"all" /
"firmware" /
"kernel" /
"privileged" /
"system-libs" /
"partial"
swresult-type = [
verification-system: tstr,
objective: verification-objective-cbor-type /
verification-objective-json-type,
result: verification-result-cbor-type /
verification-result-json-type,
? objective-name: tstr
]
]]>Some devices are complex, having many subsystems. A
mobile phone is a good example. It may have several connectivity
subsystems for communications (e.g., Wi-Fi and cellular). It may have
subsystems for low-power audio and video playback. It may have multiple
security-oriented subsystems like a TEE and a Secure Element.The claims for a subsystem can be grouped together in a submodule or submod.The submods are in a single map/object, one entry per submodule.
There is only one submods map/object in a token. It is
identified by its specific label. It is a peer to other claims, but it
is not called a claim because it is a container for a claims set rather
than an individual claim. This submods part of a token allows what
might be called recursion. It allows claims sets inside of claims sets
inside of claims sets…The following sections define the three types of submodules:A submodule Claims-SetA nested token, which can be any valid EAT token, CBOR or JSONThe digest of a detached Claims-SetThis is a subordinate Claims-Set containing claims about the submodule.The submodule claims-set is produced by the same Attester as the surrounding token.
It is secured using the same mechanism as the enclosing token (e.g., it is signed by the same attestation key).
It roughly corresponds to an Attester Target Environment, as described in the RATS architecture.It may contain claims that are the same as its surrounding token or superior submodules.
For example, the top-level of the token may have a UEID, a submod may have a different UEID and a further subordinate submodule may also have a UEID.The encoding of a submodule Claims-Set MUST be the same as the encoding as the token it is part of.This data type for this type of submodule is a map/object.
It is identified when decoding by it’s type being a map/object.This type of submodule is a fully formed complete token.
It is typically produced by a separate Attester.
It is typically used by a Composite Device as described in RATS Architecture
In being a submodule of the surrounding token, it is cryptographically bound to the surrounding token.
If it was conveyed in parallel with the surrounding token, there would be no such binding and attackers could substitute a good attestation from another device for the attestation of an errant subsystem.A nested token does not need to use the same encoding as the enclosing token.
This is to allow Composite Devices to be built without regards to the encoding supported by their Attesters.
Thus a CBOR-encoded token like a CWT or UCCS can have a JWT as a nested token submodule and a JSON-encoded token can have a CWT or UCCS as a nested token submodule.The following two sections describe how to encode and decode a nested token.This describes the encoding and decoding of CBOR or JSON-encoded tokens nested inside a CBOR-encoded token.If the nested token is CBOR-encoded, then it MUST be a CBOR tag and MUST be wrapped in a byte string.
The tag identifies whether the nested token is a CWT, a UCCS, a CBOR-encoded DEB, or some other CBOR-format token defined in the future.
A nested CBOR-encoded token that is not a CBOR tag is NOT allowed.If the nested token is JSON-encoded, then the data item MUST be a text string.
The text string MUST contain a JSON-encoded array of two items.
The first item is a string identifying the type of the token.
The second item is the JSON-encoded token.The string identifying the JSON-encoded token MUST be one of the following:
The second item MUST be a JWT formatted according to
The second item MUST be a UJCS-Message as defined in this document.
The second item MUST be a JSON-encoded Detached EAT Bundle as defined in this document.The definition of additional types requires a standards action.When decoding, if a byte string is encountered, it is known to be a nested CBOR-encoded token.
The byte string wrapping is removed.
The type of the token is determined by the CBOR tag.When decoding, if a text string is encountered, it is known to be a JSON-encoded token.
The two-item array is decoded and tells the type of the JSON-encoded token.This describes the encoding and decoding of CBOR or JSON-encoded tokens nested inside a JSON-encoded token.The nested token MUST be an array of two in the same format as described in the section above.A CBOR-encoded token nested inside a JSON-encoded MUST use the same array of two, but with the type as follows:
Some base64url-encoded CBOR that is a tag, typically a CWT, UCCS or CBOR-encoded DEBWhen decoding, the array of two is decoded.
The first item indicates the type and encoding of the nested token.
If the type string is not “CBOR”, then the token is JSON-encoded and of the type indicated by the string.If the type string is “CBOR”, then the token is CBOR-encoded.
The base64url encoding is removed.
The CBOR-encoded data is then decoded.
The type of nested token is determined by the CBOR-tag.
It is an error if the CBOR is not a tag.This is type of submodule equivalent to a Claims-Set submodule, except the Claims-Set is conveyed separately outside of the token.This type of submodule consists of a digest made using a cryptographic hash of a Claims-Set.
The Claims-Set is not included in the token.
It is conveyed to the Verifier outside of the token.
The submodule containing the digest is called a detached digest.
The separately conveyed Claims-Set is called a detached claims set.The input to the digest is exactly the byte-string wrapped encoded form of the Claims-Set for the submodule.
That Claims-Set can include other submodules including nested tokens and detached digests.The primary use for this is to facilitate the implementation of a small and secure attester, perhaps purely in hardware.
This small, secure attester implements COSE signing and only a few claims, perhaps just UEID and hardware identification.
It has inputs for digests of submodules, perhaps 32-byte hardware registers.
Software running on the device constructs larger claim sets, perhaps very large, encodes them and digests them.
The digests are written into the small secure attesters registers.
The EAT produced by the small secure attester only contains the UEID, hardware identification and digests and is thus simple enough to be implemented in hardware.
Probably, every data item in it is of fixed length.The integrity protection for the larger Claims Sets will not be as secure as those originating in hardware block, but the key material and hardware-based claims will be.
It is possible for the hardware to enforce hardware access control (memory protection) on the digest registers so that some of the larger claims can be more secure.
For example, one register may be writable only by the TEE, so the detached claims from the TEE will have TEE-level security.The data type for this type of submodule MUST be an array
It contains two data items, an algorithm identifier and a byte string containing the digest.When decoding a CBOR format token the detached digest type is distringuished from the other types by it being an array.
In CBOR the none of other submodule types are arrays.When decoding a JSON format token, a little more work is required because both the nested token and detached digest types are an array.
To distinguish the nested token from the detached digest, the first element in the array is examined.
If it is “JWT”, “UJCS” or “DEB”, the the submodule is a nested token.
Otherwise it will contain an algorithm identifier and is a detached digest.A DEB, described in , may be used to convey detached claims sets and the token with their detached digests.
EAT, however, doesn’t require use of a DEB.
Any other protocols may be used to convey detached claims sets and the token with their detached digests.
Note that since detached Claims-Sets are usually signed, protocols conveying them must make sure they are not modified in transit.The subordinate modules do not inherit anything from the containing
token. The subordinate modules must explicitly include all of their
claims. This is the case even for claims like the nonce.This rule is in place for simplicity. It avoids complex inheritance
rules that might vary from one type of claim to another.The security level of the non-token subordinate modules should always
be less than or equal to that of the containing modules in the case of non-token
submodules. It makes no sense for a module of lesser security to be
signing claims of a module of higher security. An example of this is a
TEE signing claims made by the non-TEE parts (e.g. the high-level OS)
of the device.The opposite may be true for the nested tokens. They usually have
their own more secure key material. An example of this is an embedded
secure element.The label or name for each submodule in the submods map is a text
string naming the submodule. No submodules may have the same name.The submodule type is distinguished in the encoded bytes by its data type, map/object for a Claims-Set, string for nested token and array for a detached submodule. Nested tokens are byte-string wrapped when encoded in CBOR and base64 encoded for JSON. { + text => Submodule })
Submodule = Claims-Set / Nested-Token / Detached-Submodule-Digest
Detached-Submodule-Digest = [
algorithm : int / text,
digest : bstr
]
]]>This is simply the JSON equivalent of an Unprotected CWT Claims-Set .It has no protection of its own so protections must be provided by the protocol carrying it.
These are extensively discussed in .
All the security discussion and security considerations in apply to UJCS.(Note: The EAT author is open to this definition being moved into the UCCS draft, perhaps along with the related CDDL.
It is place here for now so that the current UCCS draft plus this document are complete.
UJCS is needed for the same use cases that a UCCS is needed.
Further, JSON will commonly be used to convey Attestation Results since JSON is common for server to server communications.
Server to server communications will often have established security (e.g., TLS) therefore the signing and encryption from JWS and JWE are unnecssary and burdensome).A detached EAT bundle is a structure to convey a fully-formed and signed token plus detached claims set that relate to that token.
It is a top-level EAT message like a CWT, JWT, UCCS and UJCS.
It can be used any place that CWT, JWT, UCCS or UJCS messages are used.
It may also be sent as a submodule.A DEB has two main parts.The first part is a full top-level token.
This top-level token must have at least one submodule that is a detached digest.
This top-level token may be either CBOR or JSON-encoded.
It may be a CWT, JWT, UCCS or UJCS, but not a DEB.
The same mechanism for distinguishing the type for nested token submodules is used here.The second part is a map/object containing the detached Claims-Sets corresponding to the detached digests in the full token.
When the DEB is CBOR-encoded, each Claims-Set is wrapped in a byte string.
When the DEB is JSON-encoded, each Claims-Set is base64url encoded.
All the detached Claims-Sets MUST be encoded in the same format as the DEB.
No mixing of encoding formats is allowed for the Claims-Sets in a DEB.For CBOR-encoded DEBs, tag TBD602 can be used to identify it.
The normal rules apply for use or non-use of a tag.
When it is sent as a submodule, it is always sent as a tag to distinguish it from the other types of nested tokens.The digests of the detached claims sets are associated with detached claims-sets by label/name.
It is up to the constructor of the detached EAT bundle to ensure the names uniquely identify the detached claims sets.
Since the names are used only in the detached EAT bundle, they can be very short, perhaps one byte. cbor-wrapped-claims-set / json-wrapped-claims-set
}
]
json-wrapped-claims-set = tstr .regexp "[A-Za-z0-9_=-]+"
cbor-wrapped-claims-set = bstr .cbor Claims-Set
]]>The Verifier must possess the correct key when it performs the cryptographic part of an EAT verification (e.g., verifying the COSE/JOSE signature).
This section describes several ways to identify the verification key.
There is not one standard method.The verification key itself may be a public key, a symmetric key or something complicated in the case of a scheme like Direct Anonymous Attestation (DAA).RATS Architecture describes what is called an Endorsement.
This is an input to the Verifier that is usually the basis of the trust placed in an EAT and the Attester that generated it.
It may contain the public key for verification of the signature on the EAT.
It may contain Reference Values to which EAT claims are compared as part of the verification process.
It may contain implied claims, those that are passed on to the Relying Party in Attestation Results.There is not yet any standard format(s) for an Endorsement.
One format that may be used for an Endorsement is an X.509 certificate.
Endorsement data like Reference Values and implied claims can be carried in X.509 v3 extensions.
In this use, the public key in the X.509 certificate becomes the verification key, so identification of the Endorsement is also identification of the verification key.The verification key identification and establishment of trust in the EAT and the attester may also be by some other means than an Endorsement.For the components (Attester, Verifier, Relying Party,…) of a particular end-end attestation system to reliably interoperate, its definition should specify how the verification key is identified.
Usually, this will be in the profile document for a particular attestation system.Following is a list of possible methods of key identification. A specific attestation system may employ any one of these or one not listed here.The following assumes Endorsements are X.509 certificates or equivalent and thus does not mention or define any identifier for Endorsements in other formats. If such an Endorsement format is created, new identifiers for them will also need to be created.The COSE standard header parameter for Key ID (kid) may be used. See and COSE leaves the semantics of the key ID open-ended.
It could be a record locator in a database, a hash of a public key, an input to a KDF, an authority key identifier (AKI) for an X.509 certificate or other.
The profile document should specify what the key ID’s semantics are.COSE X.509 and JSON Web Siganture define several header parameters (x5t, x5u,…) for referencing or carrying X.509 certificates any of which may be used.The X.509 certificate may be an Endorsement and thus carrying additional input to the Verifier. It may be just an X.509 certificate, not an Endorsement. The same header parameters are used in both cases. It is up to the attestation system design and the Verifier to determine which.Compressed X.509 and CBOR Native certificates are defined by CBOR Certificates . These are semantically compatible with X.509 and therefore can be used as an equivalent to X.509 as described above.These are identified by their own header parameters (c5t, c5u,…).For some attestation systems, a claim may be re-used as a key identifier. For example, the UEID uniquely identifies the entity and therefore can work well as a key identifier or Endorsement identifier.This has the advantage that key identification requires no additional bytes in the EAT and makes the EAT smaller.This has the disadvantage that the unverified EAT must be substantially decoded to obtain the identifier since the identifier is in the COSE/JOSE payload, not in the headers.In all cases there must be some way that the verification key is itself verified or determined to be trustworthy.
The key identification itself is never enough.
This will always be by some out-of-band mechanism that is not described here.
For example, the Verifier may be configured with a root certificate or a master key by the Verifier system administrator.Often an X.509 certificate or an Endorsement carries more than just the verification key.
For example, an X.509 certificate might have key usage constraints and an Endorsement might have Reference Values.
When this is the case, the key identifier must be either a protected header or in the payload such that it is cryptographically bound to the EAT.
This is in line with the requirements in section 6 on Key Identification in JSON Web Signature .This EAT specification does not gaurantee that implementations of it will interoperate.
The variability in this specification is necessary to accommodate the widely varying use cases.
An EAT profile narrows the specification for a specific use case.
An ideal EAT profile will guarantee interoperability.The profile can be named in the token using the profile claim described in .A profile can apply to Attestation Evidence or to Attestation Results or both.A profile document doesn’t have to be in any particular format. It may be simple text, something more formal or a combination.In some cases CDDL may be created that replaces CDDL in this or other document to express some profile requirements.
For example, to require the altitude data item in the location claim, CDDL can be written that replicates the location claim with the altitude no longer optional.The following is a list of EAT, CWT, UCCS, JWS, UJCS, COSE, JOSE and CBOR options that a profile should address.The profile should indicate whether the token format should be CBOR, JSON, both or even some other encoding.
If some other encoding, a specification for how the CDDL described here is serialized in that encoding is necessary.This should be addressed for the top-level token and for any nested tokens.
For example, a profile might require all nested tokens to be of the same encoding of the top level token.The profile should indicate whether definite-length arrays/maps, indefinite-length arrays/maps or both are allowed.
A good default is to allow only definite-length arrays/maps.An alternate is to allow both definite and indefinite-length arrays/maps.
The decoder should accept either.
Encoders that need to fit on very small hardware or be actually implement in hardware can use indefinite-length encoding.This applies to individual EAT claims, CWT and COSE parts of the implementation.The profile should indicate whether definite-length strings, indefinite-length strings or both are allowed.
A good default is to allow only definite-length strings.
As with map and array encoding, allowing indefinite-length strings can be beneficial for some smaller implementations.The profile should indicate whether encoders must use preferred serialization.
The profile should indicate whether decoders must accept non-preferred serialization.COSE and JOSE have several options for signed, MACed and encrypted messages.
EAT/CWT has the option to have no protection using UCCS and JOSE has a NULL protection option.
It is possible to implement no protection, sign only, MAC only, sign then encrypt and so on.
All combinations allowed by COSE, JOSE, JWT, CWT, UCCS and UJCS are allowed by EAT.The profile should list the protections that must be supported by all decoders implementing the profile.
The encoders them must implement a subset of what is listed for the decoders, perhaps only one.Implementations may choose to sign or MAC before encryption so that the implementation layer doing the signing or MACing can be the smallest.
It is often easier to make smaller implementations more secure, perhaps even implementing in solely in hardware.
The key material for a signature or MAC is a private key, while for encryption it is likely to be a public key.
The key for encryption requires less protection.The profile document should list the COSE algorithms that a Verifier must implement.
The Attester will select one of them.
Since there is no negotiation, the Verifier should implement all algorithms listed in the profile.
If detached submodules are used, the COSE algorithms allowed for their digests should also be in the profile.A Detatched EAT Bundle is a special case message that will not often be used.
A profile may prohibit its use.Section describes a number of methods for identifying a verification key.
The profile document should specify one of these or one that is not described.
The ones described in this document are only roughly described.
The profile document should go into the full detail.Similar to, or perhaps the same as Verification Key Identification, the profile may wish to specify how Endorsements are to be identified.
However note that Endorsement Identification is optional, where as key identification is not.Just about every use case will require some means of knowing the EAT is recent enough and not a replay of an old token.
The profile should describe how freshness is achieved.
The section on Freshness in describes some of the possible solutions to achieve this.The profile can list claims whose absence results in Verification failure.The profile can list claims whose presence results in Verification failure.The profile may describe entirely new claims.
These claims can be required or optional.The profile may lock down optional aspects of individual claims.
For example, it may require altitude in the location claim, or it may require that HW Versions always be described using EAN-13.The profile should specify whether the token should be a CWT Tag or not.
Similarly, the profile should specify whether the token should be a UCCS tag or not.When COSE protection is used, the profile should specify whether COSE tags are used or not.
Note that RFC 8392 requires COSE tags be used in a CWT tag.Often a tag is unncessary because the surrounding or carrying protocol identifies the object as an EAT.The profile should specify which formats are allowed for the manifests and software evidence claims.
The profile may also go on to say which parts and options of these formats are used, allowed and prohibited.An EAT is fundamentally defined using CDDL.
This document specifies how to encode the CDDL in CBOR or JSON.
Since CBOR can express some things that JSON can’t (e.g., tags) or that are expressed differently (e.g., labels) there is some CDDL that is specific to the encoding format.CDDL was not used to define CWT or JWT.
It was not available at the time.This document defines CDDL for both CWT and JWT as well as UCCS.
This document does not change the encoding or semantics of anything in a CWT or JWT.A Claims-Set is the central data structure for EAT, CWT, JWT and UCCS.
It holds all the claims and is the structure that is secured by signing or other means.
It is not possible to define EAT, CWT, JWT or UCCS in CDDL without it.
The CDDL definition of Claims-Set here is applicable to EAT, CWT, JWT and UCCS.This document specifies how to encode a Claims-Set in CBOR or JSON.With the exception of nested tokens and some other externally defined structures (e.g., SWIDs) an entire Claims-Set must be in encoded in either CBOR or JSON, never a mixture.CDDL for the seven claims defined by and is included here.This makes use of the types defined in Appendix D, Standard Prelude.time-int is identical to the epoch-based time, but disallows
floating-point representation.Unless expliclity indicated, URIs are not the URI tag defined in .
They are just text strings that contain a URI.JSON should be encoded per Appendix E. In addition, the
following CDDL types are encoded in JSON as follows:bstr – must be base64url encodedtime – must be encoded as NumericDate as described section 2 of .string-or-uri – must be encoded as StringOrURI as described section 2 of .uri – must be a URI .oid – encoded as a string using the well established dotted-decimal notation (e.g., the text “1.2.250.1”).Map labels, including Claims-Keys and Claim-Names, and enumerated-type values are always integers when encoding in CBOR and strings when encoding in JSON.
There is an exception to this for naming submodules and detached claims sets in a DEB.
These are strings in CBOR.The CDDL in most cases gives both the integer label and the string label as it is not convenient to have conditional CDDL for such.CBOR allows data items to be serialized in more than one form.
If the sender uses a form that the receiver can’t decode, there will not be interoperability.This specification gives no blanket requirements to narrow CBOR serialization for all uses of EAT.
This allows individual uses to tailor serialization to the environment.
It also may result in EAT implementations that don’t interoperate.One way to guarantee interoperability is to clearly specify CBOR serialization in a profile document.
See for a list of serialization issues that should be addressed.EAT will be commonly used where the entity generating the attestation is constrained and the receiver/Verifier of the attestation is a capacious server.
Following is a set of serialization requirements that work well for that use case and are guaranteed to interoperate.
Use of this serialization is recommended where possible, but not required.
An EAT profile may just reference the following section rather than spell out serialization details.Preferred serialization described in section 4.1 of is not required.
The EAT decoder must accept all forms of number serialization.
The EAT encoder may use any form it wishes.The EAT decoder must accept indefinite length arrays and maps as described in section 3.2.2 of .
The EAT encoder may use indefinite length arrays and maps if it wishes.The EAT decoder must accept indefinite length strings as described in section 3.2.3 of .
The EAT encoder may use indefinite length strings if it wishes.Sorting of maps by key is not required.
The EAT decoder must not rely on sorting.Deterministic encoding described in Section 4.2 of is not required.Basic validity described in section 5.3.1 of must be followed.
The EAT encoder must not send duplicate map keys/labels or invalid UTF-8 strings. any
}
Claim-Label = int / text
string-or-uri = tstr
time-int = #6.1(int)
$$claims-set-claims //= (iss-label => text)
$$claims-set-claims //= (sub-label => text)
$$claims-set-claims //= (aud-label => text)
$$claims-set-claims //= (exp-label => ~time)
$$claims-set-claims //= (nbf-label => ~time)
$$claims-set-claims //= (iat-label => ~time)
$$claims-set-claims //=
(nonce-label => nonce-type / [ 2* nonce-type ])
nonce-type = bstr .size (8..64)
$$claims-set-claims //= (ueid-label => ueid-type)
ueid-type = bstr .size (7..33)
$$claims-set-claims //= (sueids-label => sueids-type)
sueids-type = {
+ tstr => ueid-type
}
oemid-pen = int
oemid-ieee = bstr .size 3
oemid-random = bstr .size 16
$$claims-set-claims //= (
oemid-label =>
oemid-random / oemid-ieee / oemid-pen
)
$$claims-set-claims //= (
hardware-version-label => hardware-version-type
)
hardware-version-type = [
version: tstr,
scheme: $version-scheme
]
hardware-model-type = bytes .size (1..32)
$$claims-set-claims //= (
hardware-model-label => hardware-model-type
)
$$claims-set-claims //= ( sw-name-label => tstr )
$$claims-set-claims //= (sw-version-label => sw-version-type)
sw-version-type = [
version: tstr,
scheme: $version-scheme ; As defined by CoSWID
]
$$claims-set-claims //= (
security-level-label =>
security-level-cbor-type /
security-level-json-type
)
security-level-cbor-type = &(
unrestricted: 1,
restricted: 2,
secure-restricted: 3,
hardware: 4
)
security-level-json-type =
"unrestricted" /
"restricted" /
"secure-restricted" /
"hardware"
$$claims-set-claims //= (secure-boot-label => bool)
$$claims-set-claims //= (
debug-status-label =>
debug-status-cbor-type / debug-status-json-type
)
debug-status-cbor-type = &(
enabled: 0,
disabled: 1,
disabled-since-boot: 2,
disabled-permanently: 3,
disabled-fully-and-permanently: 4
)
debug-status-json-type =
"enabled" /
"disabled" /
"disabled-since-boot" /
"disabled-permanently" /
"disabled-fully-and-permanently"
$$claims-set-claims //= (location-label => location-type)
location-type = {
latitude => number,
longitude => number,
? altitude => number,
? accuracy => number,
? altitude-accuracy => number,
? heading => number,
? speed => number,
? timestamp => ~time-int,
? age => uint
}
latitude = 1 / "latitude"
longitude = 2 / "longitude"
altitude = 3 / "altitude"
accuracy = 4 / "accuracy"
altitude-accuracy = 5 / "altitude-accuracy"
heading = 6 / "heading"
speed = 7 / "speed"
timestamp = 8 / "timestamp"
age = 9 / "age"
$$claims-set-claims //= (uptime-label => uint)
$$claims-set-claims //= (boot-seed-label => bytes)
$$claims-set-claims //= (odometer-label => uint)
$$claims-set-claims //= (
intended-use-label =>
intended-use-cbor-type / intended-use-json-type
)
intended-use-cbor-type = &(
generic: 1,
registration: 2,
provisioning: 3,
csr: 4,
pop: 5
)
intended-use-json-type =
"generic" /
"registration" /
"provisioning" /
"csr" /
"pop"
$$claims-set-claims //= (
dloas-label => [ + dloa-type ]
)
dloa-type = [
dloa_registrar: ~uri
dloa_platform_label: text
? dloa_application_label: text
]
$$claims-set-claims //= (profile-label => ~uri / ~oid)
$$claims-set-claims //= (
manifests-label => manifests-type
)
manifests-type = [+ $$manifest-formats]
coswid-that-is-a-cbor-tag-xx = tagged-coswid
$$manifest-formats /= bytes .cbor coswid-that-is-a-cbor-tag-xx$$claims-set-claims //= (
swevidence-label => swevidence-type
)
swevidence-type = [+ $$swevidence-formats]
coswid-that-is-a-cbor-tag = tagged-coswid
$$swevidence-formats /= bytes .cbor coswid-that-is-a-cbor-tag
$$claims-set-claims //= (swresults-label => [ + swresult-type ])
verification-result-cbor-type = &(
verification-not-run: 1,
verification-indeterminate: 2,
verification-failed: 3,
fully-verified: 4,
partially-verified: 5,
)
verification-result-json-type =
"verification-not-run" /
"verification-indeterminate" /
"verification-failed" /
"fully-verified" /
"partially-verified"
verification-objective-cbor-type = &(
all: 1,
firmware: 2,
kernel: 3,
privileged: 4,
system-libs: 5,
partial: 6,
)
verification-objective-json-type =
"all" /
"firmware" /
"kernel" /
"privileged" /
"system-libs" /
"partial"
swresult-type = [
verification-system: tstr,
objective: verification-objective-cbor-type /
verification-objective-json-type,
result: verification-result-cbor-type /
verification-result-json-type,
? objective-name: tstr
]
$$claims-set-claims //= (submods-label => { + text => Submodule })
Submodule = Claims-Set / Nested-Token / Detached-Submodule-Digest
Detached-Submodule-Digest = [
algorithm : int / text,
digest : bstr
]
Detached-EAT-Bundle = [
main-token : Nested-Token,
detached-claims-sets: {
+ tstr => cbor-wrapped-claims-set / json-wrapped-claims-set
}
]
json-wrapped-claims-set = tstr .regexp "[A-Za-z0-9_=-]+"
cbor-wrapped-claims-set = bstr .cbor Claims-Set
]]>
uptime-label =
boot-seed-label =
odometer-label =
intended-use-label =
dloas-label =
sw-name-label =
sw-version-label =
manifests-label =
swevidence-label =
swresults-label =
]]>Claims defined for EAT are compatible with those of CWT and JWT
so the CWT and JWT Claims Registries, and , are re used. No new IANA registry
is created.All EAT claims defined in this document are placed in both registries.
All new EAT claims defined subsequently should be placed in both registries.The following is design guidance for creating new EAT claims, particularly those to be registered with IANA.Much of this guidance is generic and could also be considered when designing new CWT or JWT claims.It is a broad goal that EATs can be processed by Relying Parties in a general way regardless of the type, manufacturer or technology of the device from which they originate.
It is a goal that there be general-purpose verification implementations that can verify tokens for large numbers of use cases with special cases and configurations for different device types.
This is a goal of interoperability of the semantics of claims themselves, not just of the signing, encoding and serialization formats.This is a lofty goal and difficult to achieve broadly requiring careful definition of claims in a technology neutral way.
Sometimes it will be difficult to design a claim that can represent the semantics of data from very different device types.
However, the goal remains even when difficult.Claims should be defined such that they are not specific to an operating system.
They should be applicable to multiple large high-level operating systems from different vendors.
They should also be applicable to multiple small embedded operating systems from multiple vendors and everything in between.Claims should not be defined such that they are specific to a SW environment or programming language.Claims should not be defined such that they are specific to a chip or particular hardware.
For example, they should not just be the contents of some HW status register as it is unlikely that the same HW status register with the same bits exists on a chip of a different manufacturer.The boot and debug state claims in this document are an example of a claim that has been defined in this neutral way.Many use cases will have EATs generated by some of the most secure hardware and software that exists.
Secure Elements and smart cards are examples of this.
However, EAT is intended for use in low-security use cases the same as high-security use case.
For example, an app on a mobile device may generate EATs on its own.Claims should be defined and registered on the basis of whether they are useful and interoperable, not based on security level.
In particular, there should be no exclusion of claims because they are just used only in low-security environments.Where possible, claims should use already standardized data items, identifiers and formats.
This takes advantage of the expertise put into creating those formats and improves interoperability.Often extant claims will not be defined in an encoding or serialization format used by EAT.
It is preferred to define a CBOR and JSON format for them so that EAT implementations do not require a plethora of encoders and decoders for serialization formats.In some cases, it may be better to use the encoding and serialization as is.
For example, signed X.509 certificates and CRLs can be carried as-is in a byte string.
This retains interoperability with the extensive infrastructure for creating and processing X.509 certificates and CRLs.EAT allows the definition and use of proprietary claims.For example, a device manufacturer may generate a token with proprietary claims intended only for verification by a service offered by that device manufacturer.
This is a supported use case.In many cases proprietary claims will be the easiest and most obvious way to proceed, however for better interoperability, use of general standardized claims is preferred.This specification adds the following values to the “JSON Web Token
Claims” registry established by and the “CBOR Web Token Claims Registry”
established by . Each entry below is an addition to both registries (except
for the nonce claim which is already registered for JWT, but not registered for CWT).The “Claim Description”, “Change Controller” and “Specification Documents” are common and equivalent for the JWT and CWT registries.
The “Claim Key” and “Claim Value Types(s)” are for the CWT registry only.
The “Claim Name” is as defined for the CWT registry, not the JWT registry.
The “JWT Claim Name” is equivalent to the “Claim Name” in the JWT registry.RFC Editor: in the final publication this section should be combined with the following
section as it will no longer be necessary to distinguish claims with early assignment.
Also, the following paragraph should be removed.The claims in this section have been (requested for / given) early assignment according to .
They have been assigned values and registered before final publication of this document.
While their semantics is not expected to change in final publication, it is possible that they will.
The JWT Claim Names and CWT Claim Keys are not expected to change.In draft -06 an early allocation was described.
The processing of that early allocation was never correctly completed.
This early allocation assigns different numbers for the CBOR claim labels.
This early allocation will presumably complete correctlyClaim Name: NonceClaim Description: NonceJWT Claim Name: “nonce” (already registered for JWT)Claim Key: TBD (requested value 10)Claim Value Type(s): byte stringChange Controller: IESGSpecification Document(s): , this documentClaim Name: UEIDClaim Description: The Universal Entity IDJWT Claim Name: “ueid”CWT Claim Key: TBD (requested value 256)Claim Value Type(s): byte stringChange Controller: IESGSpecification Document(s): this documentClaim Name: SUEIDsClaim Description: Semi-permanent UEIDsJWT Claim Name: “sueids”CWT Claim Key: TBD (requested value 257)Claim Value Type(s): mapChange Controller: IESGSpecification Document(s): this documentClaim Name: Hardware OEMIDClaim Description: Hardware OEM IDJWT Claim Name: “oemid”Claim Key: TBD (requested value 258)Claim Value Type(s): byte string or integerChange Controller: IESGSpecification Document(s): this documentClaim Name: Hardware ModelClaim Description: Model identifier for hardwareJWT Claim Name: “hwmodel”Claim Key: TBD (requested value 259)Claim Value Type(s): byte stringChange Controller: IESGSpecification Document(s): this documentClaim Name: Hardware VersionClaim Description: Hardware Version IdentifierJWT Claim Name: “hwversion”Claim Key: TBD (requested value 260)Claim Value Type(s): arrayChange Controller: IESGSpecification Document(s): this documentClaim Name: Secure BootClaim Description: Indicate whether the boot was secureJWT Claim Name: “secboot”Claim Key: TBD (requested value 262)Claim Value Type(s): BooleanChange Controller: IESGSpecification Document(s): this documentClaim Name: Debug StatusClaim Description: Indicate status of debug facilitiesJWT Claim Name: “dbgstat”Claim Key: TBD (requested value 263)Claim Value Type(s): integer or stringChange Controller: IESGSpecification Document(s): this documentClaim Name: LocationClaim Description: The geographic locationJWT Claim Name: “location”Claim Key: TBD (requested value 264)Claim Value Type(s): mapChange Controller: IESGSpecification Document(s): this documentClaim Name: ProfileClaim Description: Indicates the EAT profile followedJWT Claim Name: “eat_profile”Claim Key: TBD (requested value 265)Claim Value Type(s): URI or OIDChange Controller: IESGSpecification Document(s): this documentClaim Name: Submodules SectionClaim Description: The section containing submodulesJWT Claim Name: “submods”Claim Key: TBD (requested value 266)Claim Value Type(s): mapChange Controller: IESGSpecification Document(s): this document(Early assignment is NOT requested for these claims. Implementers should be aware they may change)Claim Name: Security LevelClaim Description: Characterization of the security of an Attester or submoduleJWT Claim Name: “seclevel”Claim Key: TBDClaim Value Type(s): integer or stringChange Controller: IESGSpecification Document(s): this documentClaim Name: UptimeClaim Description: UptimeJWT Claim Name: “uptime”Claim Key: TBDClaim Value Type(s): unsigned integerChange Controller: IESGSpecification Document(s): this documentClaim Name: Boot SeedClaim Description: Identifies a boot cycleJWT Claim Name: “bootseed”Claim Key: TBDClaim Value Type(s): bytesChange Controller: IESGSpecification Document(s): this documentClaim Name: Intended UseClaim Description: Indicates intended use of the EATJWT Claim Name: “intuse”Claim Key: TBDClaim Value Type(s): integer or stringChange Controller: IESGSpecification Document(s): this documentClaim Name: DLOAsClaim Description: Certifications received as Digital Letters of ApprovalJWT Claim Name: “dloas”Claim Key: TBDClaim Value Type(s): arrayChange Controller: IESGSpecification Document(s): this documentClaim Name: SW NameClaim Description: The name of the SW running in the entityJWT Claim Name: “swname”Claim Key: TBDClaim Value Type(s): mapChange Controller: IESGSpecification Document(s): this documentClaim Name: SW VersionClaim Description: The version of SW running in the entityJWT Claim Name: “swversion”Claim Key: TBDClaim Value Type(s): mapChange Controller: IESGSpecification Document(s): this documentClaim Name: SW ManifestsClaim Description: Manifests describing the SW installed on the entityJWT Claim Name: “manifests”Claim Key: TBDClaim Value Type(s): arrayChange Controller: IESGSpecification Document(s): this documentClaim Name: SW EvidenceClaim Description: Measurements of the SW, memory configuration and such on the entityJWT Claim Name: “swevidence”Claim Key: TBDClaim Value Type(s): arrayChange Controller: IESGSpecification Document(s): this documentClaim Name: SW Measurment ResultsClaim Description: The results of comparing SW measurements to reference valuesJWT Claim Name: “swresults”Claim Key: TBDClaim Value Type(s): arrayChange Controller: IESGSpecification Document(s): this documentIANA is requested to register a new value in the “Software Tag Version Scheme Values” established by .The new value is a version scheme a 13-digit European Article Number .
An EAN-13 is also known as an International Article Number or most commonly as a bar code.
This version scheme is the ASCII text representation of EAN-13 digits, the same ones often printed with a bar code.
This version scheme must comply with the EAN allocation and assignment rules.
For example, this requires the manufacturer to obtain a manufacture code from GS1.IndexVersion Scheme NameSpecification5ean-13This documentIANA is requested to register the following new subtypes in the “DEV URN Subtypes” registry under “Device Identification”. See .SubtypeDescriptionReferenceueidUniversal Entity IdentifierThis documentsueidSemi-permanent Universal Entity IdentifierThis documentIn the registry , IANA is requested to allocate the
following tag from the FCFS space, with the present document as the
specification reference.TagData ItemsSemanticsTBD602arrayDetached EAT Bundle Certain EAT claims can be used to track the owner of an entity and
therefore, implementations should consider providing privacy-preserving
options dependent on the intended usage of the EAT. Examples would
include suppression of location claims for EAT’s provided to
unauthenticated consumers.A UEID is usually not privacy-preserving. Any set of Relying Parties
that receives tokens that happen to be from a particular entity will be
able to know the tokens are all from the same entity and be able to
track it.Thus, in many usage situations UEID violates
governmental privacy regulation. In other usage situations a UEID will
not be allowed for certain products like browsers that give privacy
for the end user. It will often be the case that tokens will not have
a UEID for these reasons.An SUEID is also usually not privacy-preserving. In some cases it may
have fewer privacy issues than a UEID depending on when and how and
when it is generated.There are several strategies that can be used to still be able to put
UEIDs and SUEIDs in tokens:The entity obtains explicit permission from the user of the entity
to use the UEID/SUEID. This may be through a prompt. It may also be through
a license agreement. For example, agreements for some online banking
and brokerage services might already cover use of a UEID/SUEID.The UEID/SUEID is used only in a particular context or particular use
case. It is used only by one Relying Party.The entity authenticates the Relying Party and generates a derived
UEID/SUEID just for that particular Relying Party. For example, the Relying
Party could prove their identity cryptographically to the entity, then
the entity generates a UEID just for that Relying Party by hashing a
proofed Relying Party ID with the main entity UEID/SUEID.Note that some of these privacy preservation strategies result in
multiple UEIDs and SUEIDs per entity. Each UEID/SUEID is used in a
different context, use case or system on the entity. However, from the
view of the Relying Party, there is just one UEID and it is still
globally universal across manufacturers.Geographic location is most always considered personally identifiable information.
Implementers should consider laws and regulations governing the transmission of location data from end user devices to servers and services.
Implementers should consider using location management facilities offered by the operating system on the entity generating the attestation.
For example, many mobile phones prompt the user for permission when before sending location data.EAT offers 2 primary mechanisms for token replay protection (also sometimes
known as token “freshness”): the cti/jti claim and the nonce claim. The cti/jti claim
in a CWT/JWT is a field that may be optionally included in the EAT and is in general
derived on the same device in which the entity is instantiated. The nonce claim is based
on a value that is usually derived remotely (outside of the entity). These claims can be used
to extract and convey personally-identifying information either inadvertently or by intention. For instance,
an implementor may choose a cti that is equivalent to a username associated with the device (e.g., account
login). If the token is inspected by a 3rd-party then this information could be used to identify the source
of the token or an account associated with the token (e.g., if the account name is used to derive the nonce). In order
to avoid the conveyance of privacy-related information in either the cti/jti or nonce claims, these fields
should be derived using a salt that originates from a true and reliable random number generator or any other
source of randomness that would still meet the target system requirements for replay protection.The security considerations provided in Section 8 of and Section 11
of apply to EAT in its CWT and JWT form, respectively. In addition,
implementors should consider the following.Private key material can be used to sign and/or encrypt the EAT, or
can be used to derive the keys used for signing and/or encryption. In
some instances, the manufacturer of the entity may create the key
material separately and provision the key material in the entity
itself. The manfuacturer of any entity that is capable of producing
an EAT should take care to ensure that any private key material be
suitably protected prior to provisioning the key material in the
entity itself. This can require creation of key material in an
enclave (see for definition of “enclave”), secure
transmission of the key material from the enclave to the entity using
an appropriate protocol, and persistence of the private key material
in some form of secure storage to which (preferably) only the entity
has access.Regarding transmission of key material from the enclave to the entity,
the key material may pass through one or more intermediaries.
Therefore some form of protection (“key wrapping”) may be necessary.
The transmission itself may be performed electronically, but can also
be done by human courier. In the latter case, there should be minimal
to no exposure of the key material to the human (e.g. encrypted
portable memory). Moreover, the human should transport the key
material directly from the secure enclave where it was created to a
destination secure enclave where it can be provisioned.As stated in Section 8 of , “The security of the CWT relies
upon on the protections offered by COSE”. Similar considerations
apply to EAT when sent as a CWT. However, EAT introduces the concept
of a nonce to protect against replay. Since an EAT may be created by
an entity that may not support the same type of transport security as
the consumer of the EAT, intermediaries may be required to bridge
communications between the entity and consumer. As a result, it is
RECOMMENDED that both the consumer create a nonce, and the entity
leverage the nonce along with COSE mechanisms for encryption and/or
signing to create the EAT.Similar considerations apply to the use of EAT as a JWT. Although the
security of a JWT leverages the JSON Web Encryption (JWE) and JSON Web
Signature (JWS) specifications, it is still recommended to make use of
the EAT nonce.In many cases, more than one EAT consumer may be required to fully
verify the entity attestation. Examples include individual consumers
for nested EATs, or consumers for individual claims with an EAT. When
multiple consumers are required for verification of an EAT, it is
important to minimize information exposure to each consumer. In
addition, the communication between multiple consumers should be
secure.For instance, consider the example of an encrypted and signed EAT with
multiple claims. A consumer may receive the EAT (denoted as the
“receiving consumer”), decrypt its payload, verify its signature, but
then pass specific subsets of claims to other consumers for evaluation
(“downstream consumers”). Since any COSE encryption will be removed
by the receiving consumer, the communication of claim subsets to any
downstream consumer should leverage a secure protocol (e.g.one that
uses transport-layer security, i.e. TLS),However, assume the EAT of the previous example is hierarchical and
each claim subset for a downstream consumer is created in the form of
a nested EAT. Then transport security between the receiving and
downstream consumers is not strictly required. Nevertheless,
downstream consumers of a nested EAT should provide a nonce unique to
the EAT they are consuming.Key words for use in RFCs to Indicate Requirement LevelsIn many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.The JavaScript Object Notation (JSON) Data Interchange FormatJavaScript Object Notation (JSON) is a lightweight, text-based, language-independent data interchange format. It was derived from the ECMAScript Programming Language Standard. JSON defines a small set of formatting rules for the portable representation of structured data.This document removes inconsistencies with other specifications of JSON, repairs specification errors, and offers experience-based interoperability guidance.JSON Web Signature (JWS)JSON Web Signature (JWS) represents content secured with digital signatures or Message Authentication Codes (MACs) using JSON-based data structures. Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) specification and an IANA registry defined by that specification. Related encryption capabilities are described in the separate JSON Web Encryption (JWE) specification.JSON Web Encryption (JWE)JSON Web Encryption (JWE) represents encrypted content using JSON-based data structures. Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) specification and IANA registries defined by that specification. Related digital signature and Message Authentication Code (MAC) capabilities are described in the separate JSON Web Signature (JWS) specification.Concise Binary Object Representation (CBOR)The Concise Binary Object Representation (CBOR) is a data format whose design goals include the possibility of extremely small code size, fairly small message size, and extensibility without the need for version negotiation. These design goals make it different from earlier binary serializations such as ASN.1 and MessagePack.This document obsoletes RFC 7049, providing editorial improvements, new details, and errata fixes while keeping full compatibility with the interchange format of RFC 7049. It does not create a new version of the format.JSON Web Key (JWK)A JSON Web Key (JWK) is a JavaScript Object Notation (JSON) data structure that represents a cryptographic key. This specification also defines a JWK Set JSON data structure that represents a set of JWKs. Cryptographic algorithms and identifiers for use with this specification are described in the separate JSON Web Algorithms (JWA) specification and IANA registries established by that specification.JSON Web Token (JWT)JSON Web Token (JWT) is a compact, URL-safe means of representing claims to be transferred between two parties. The claims in a JWT are encoded as a JSON object that is used as the payload of a JSON Web Signature (JWS) structure or as the plaintext of a JSON Web Encryption (JWE) structure, enabling the claims to be digitally signed or integrity protected with a Message Authentication Code (MAC) and/or encrypted.Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs)This specification describes how to declare in a JSON Web Token (JWT) that the presenter of the JWT possesses a particular proof-of- possession key and how the recipient can cryptographically confirm proof of possession of the key by the presenter. Being able to prove possession of a key is also sometimes described as the presenter being a holder-of-key.Guidelines for Writing an IANA Considerations Section in RFCsMany protocols make use of points of extensibility that use constants to identify various protocol parameters. To ensure that the values in these fields do not have conflicting uses and to promote interoperability, their allocations are often coordinated by a central record keeper. For IETF protocols, that role is filled by the Internet Assigned Numbers Authority (IANA).To make assignments in a given registry prudently, guidance describing the conditions under which new values should be assigned, as well as when and how modifications to existing values can be made, is needed. This document defines a framework for the documentation of these guidelines by specification authors, in order to assure that the provided guidance for the IANA Considerations is clear and addresses the various issues that are likely in the operation of a registry.This is the third edition of this document; it obsoletes RFC 5226.Ambiguity of Uppercase vs Lowercase in RFC 2119 Key WordsRFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings.CBOR Web Token (CWT)CBOR Web Token (CWT) is a compact means of representing claims to be transferred between two parties. The claims in a CWT are encoded in the Concise Binary Object Representation (CBOR), and CBOR Object Signing and Encryption (COSE) is used for added application-layer security protection. A claim is a piece of information asserted about a subject and is represented as a name/value pair consisting of a claim name and a claim value. CWT is derived from JSON Web Token (JWT) but uses CBOR rather than JSON.Concise Data Definition Language (CDDL): A Notational Convention to Express Concise Binary Object Representation (CBOR) and JSON Data StructuresThis document proposes a notational convention to express Concise Binary Object Representation (CBOR) data structures (RFC 7049). Its main goal is to provide an easy and unambiguous way to express structures for protocol messages and data formats that use CBOR or JSON.Proof-of-Possession Key Semantics for CBOR Web Tokens (CWTs)This specification describes how to declare in a CBOR Web Token (CWT) (which is defined by RFC 8392) that the presenter of the CWT possesses a particular proof-of-possession key. Being able to prove possession of a key is also sometimes described as being the holder-of-key. This specification provides equivalent functionality to "Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs)" (RFC 7800) but using Concise Binary Object Representation (CBOR) and CWTs rather than JavaScript Object Notation (JSON) and JSON Web Tokens (JWTs).Uniform Resource Identifier (URI): Generic SyntaxA Uniform Resource Identifier (URI) is a compact sequence of characters that identifies an abstract or physical resource. This specification defines the generic URI syntax and a process for resolving URI references that might be in relative form, along with guidelines and security considerations for the use of URIs on the Internet. The URI syntax defines a grammar that is a superset of all valid URIs, allowing an implementation to parse the common components of a URI reference without knowing the scheme-specific requirements of every possible identifier. This specification does not define a generative grammar for URIs; that task is performed by the individual specifications of each URI scheme. [STANDARDS-TRACK]CBOR Object Signing and Encryption (COSE)Concise Binary Object Representation (CBOR) is a data format designed for small code size and small message size. There is a need for the ability to have basic security services defined for this data format. This document defines the CBOR Object Signing and Encryption (COSE) protocol. This specification describes how to create and process signatures, message authentication codes, and encryption using CBOR for serialization. This specification additionally describes how to represent cryptographic keys using CBOR.Concise Binary Object Representation (CBOR) Tags for Object IdentifiersThe Concise Binary Object Representation (CBOR), defined in RFC 8949, is a data format whose design goals include the possibility of extremely small code size, fairly small message size, and extensibility without the need for version negotiation.This document defines CBOR tags for object identifiers (OIDs) and is the reference document for the IANA registration of the CBOR tags so defined.WORLD GEODETIC SYSTEM 1984, NGA.STND.0036_1.0.0_WGS84National Geospatial-Intelligence Agency (NGA)CBOR Web Token (CWT) ClaimsIANAJSON Web Token (JWT) ClaimsIANAA CBOR Tag for Unprotected CWT Claims SetsFraunhofer SITQualcomm Technologies Inc.Cisco SystemsUniversität Bremen TZI CBOR Web Token (CWT, RFC 8392) Claims Sets sometimes do not need the
protection afforded by wrapping them into COSE, as is required for a
true CWT. This specification defines a CBOR tag for such unprotected
CWT Claims Sets (UCCS) and discusses conditions for its proper use.
// The present version (-01) has a few editorial improvements over
// -00 and attempts to address points from Thomas Fossati's
// 2021-03-16 review, for further discussion at IETF 111.
3rd Generation Partnership Project; Technical Specification Group Core Network and Terminals; Numbering, addressing and identification3GPPFIDO Authenticator Allowed Restricted Operating Environments ListThe FIDO AllianceInternational Article Number - EAN/UPC barcodesGS1Concise Software Identification TagsFraunhofer SITNational Security AgencyThe MITRE CorporationNational Institute of Standards and Technology ISO/IEC 19770-2:2015 Software Identification (SWID) tags provide an
extensible XML-based structure to identify and describe individual
software components, patches, and installation bundles. SWID tag
representations can be too large for devices with network and storage
constraints. This document defines a concise representation of SWID
tags: Concise SWID (CoSWID) tags. CoSWID supports a similar set of
semantics and features as SWID tags, as well as new semantics that
allow CoSWIDs to describe additional types of information, all in a
more memory efficient format.
OpenID Connect Core 1.0 incorporating errata set 1Digital Letter of ApprovalPrivate Enterprise Number (PEN) RequestIANA CBOR Tags RegistryA Universally Unique IDentifier (UUID) URN NamespaceThis specification defines a Uniform Resource Name namespace for UUIDs (Universally Unique IDentifier), also known as GUIDs (Globally Unique IDentifier). A UUID is 128 bits long, and can guarantee uniqueness across space and time. UUIDs were originally used in the Apollo Network Computing System and later in the Open Software Foundation\'s (OSF) Distributed Computing Environment (DCE), and then in Microsoft Windows platforms.This specification is derived from the DCE specification with the kind permission of the OSF (now known as The Open Group). Information from earlier versions of the DCE specification have been incorporated into this document. [STANDARDS-TRACK]Simple Authentication and Security Layer (SASL)The Simple Authentication and Security Layer (SASL) is a framework for providing authentication and data security services in connection-oriented protocols via replaceable mechanisms. It provides a structured interface between protocols and mechanisms. The resulting framework allows new protocols to reuse existing mechanisms and allows old protocols to make use of new mechanisms. The framework also provides a protocol for securing subsequent protocol exchanges within a data security layer.This document describes how a SASL mechanism is structured, describes how protocols include support for SASL, and defines the protocol for carrying a data security layer over a connection. In addition, this document defines one SASL mechanism, the EXTERNAL mechanism.This document obsoletes RFC 2222. [STANDARDS-TRACK]Internet Security Glossary, Version 2This Glossary provides definitions, abbreviations, and explanations of terminology for information system security. The 334 pages of entries offer recommendations to improve the comprehensibility of written material that is generated in the Internet Standards Process (RFC 2026). The recommendations follow the principles that such writing should (a) use the same term or definition whenever the same concept is mentioned; (b) use terms in their plainest, dictionary sense; (c) use terms that are already well-established in open publications; and (d) avoid terms that either favor a particular vendor or favor a particular technology or mechanism over other, competing techniques that already exist or could be developed. This memo provides information for the Internet community.Early IANA Allocation of Standards Track Code PointsThis memo describes the process for early allocation of code points by IANA from registries for which "Specification Required", "RFC Required", "IETF Review", or "Standards Action" policies apply. This process can be used to alleviate the problem where code point allocation is needed to facilitate desired or required implementation and deployment experience prior to publication of an RFC, which would normally trigger code point allocation. The procedures in this document are intended to apply only to IETF Stream documents.The Transport Layer Security (TLS) Protocol Version 1.3This document specifies version 1.3 of the Transport Layer Security (TLS) protocol. TLS allows client/server applications to communicate over the Internet in a way that is designed to prevent eavesdropping, tampering, and message forgery.This document updates RFCs 5705 and 6066, and obsoletes RFCs 5077, 5246, and 6961. This document also specifies new requirements for TLS 1.2 implementations.Uniform Resource Names for Device IdentifiersThis document describes a new Uniform Resource Name (URN) namespace for hardware device identifiers. A general representation of device identity can be useful in many applications, such as in sensor data streams and storage or in equipment inventories. A URN-based representation can be passed along in applications that need the information.Remote Attestation Procedures ArchitectureFraunhofer SITMicrosoftSandelman Software WorksIntel CorporationHuawei Technologies In network protocol exchanges it is often useful for one end of a
communication to know whether the other end is in an intended
operating state. This document provides an architectural overview of
the entities involved that make such tests possible through the
process of generating, conveying, and evaluating evidentiary claims.
An attempt is made to provide for a model that is neutral toward
processor architectures, the content of claims, and protocols.
Birthday attackIEEE Standard, "IEEE 802.1AR Secure Device Identifier"Geolocation API Specification 2nd EditionWorldwide Web ConsortiumGuidelines for Use of Extended Unique Identifier (EUI), Organizationally Unique Identifier (OUI), and Company ID (CID)IEEE Registration Authority AssignmentsIEEE Registration AuthorityIEEE Standard For Local And Metropolitan Area Networks Overview And ArchitectureSecurity Requirements for Cryptographic ModulesNational Institue of StandardsCommon Criteria for Information Technology Security EvaluationCBOR Object Signing and Encryption (COSE): Header parameters for carrying and referencing X.509 certificatesThe CBOR Signing And Encrypted Message (COSE) structure uses references to keys in general. For some algorithms, additional properties are defined which carry parameters relating to keys as needed. The COSE Key structure is used for transporting keys outside of COSE messages. This document extends the way that keys can be identified and transported by providing attributes that refer to or contain X.509 certificates.CBOR Encoded X.509 Certificates (C509 Certificates)Ericsson ABEricsson ABRISE ABRISE ABNexus Group This document specifies a CBOR encoding of X.509 certificates. The
resulting certificates are called C509 Certificates. The CBOR
encoding supports a large subset of RFC 5280 and all certificates
compatible with the RFC 7925, IEEE 802.1AR (DevID), CNSA, RPKI, GSMA
eUICC, and CA/Browser Forum Baseline Requirements profiles. When
used to re-encode DER encoded X.509 certificates, the CBOR encoding
can in many cases reduce the size of RFC 7925 profiled certificates
with over 50%. The CBOR encoded structure can alternatively be
signed directly ("natively signed"), which does not require re-
encoding for the signature to be verified. The document also
specifies C509 COSE headers, a C509 TLS certificate type, and a C509
file format.
These examples are either UCCS, shown as CBOR diagnostic, or UJCS messages.
Full CWT and JWT examples with signing and encryption are not given.All UCCS examples can be the payload of a CWT.
To do so, they must be converted from the UCCS message to a Claims-Set, which is achieve by “removing” the tag.UJCS messages can be directly used as the payload of a JWT.WARNING: These examples use tag and label numbers not yet assigned by IANA.This is a simple attestation of a TEE that includes a manifest that is a payload CoSWID to describe the TEE’s software.In this DEB main token is produced by a HW attestation block.
The detached Claims-Set is produced by a TEE and is largely identical to the Simple TEE examples above.
The TEE digests its Claims-Set and feeds that digest to the HW block.In a better example the attestation produced by the HW block would be a CWT and thus signed and secured by the HW block.
Since the signature covers the digest from the TEE that Claims-Set is also secured.The DEB itself can be assembled by untrusted SW.This is a simple token that might be for and IoT device.
It includes CoSWID format measurments of the SW.
The CoSWID is in byte-string wrapped in the token and also shown in diagnostic form.This is a UJCS format token that might be the output of a Verifier that evaluated the IoT Attestation example immediately above.This particular Verifier knows enough about the TEE Attester to be able to pass claims like security level directly through to the Relying Party.
The Verifier also knows the Reference Values for the measured SW components and is able to check them.
It informs the Relying Party that they were correct in the swresults claim.
“Trustus Verifications” is the name of the services that verifies the SW component measurements.This UJCS is identical to JSON-encoded Claims-Set that could be a JWT payload.This calculation is to determine the probability of a collision of
UEIDs given the total possible entity population and the number of
entities in a particular entity management database.Three different sized databases are considered. The number of devices
per person roughly models non-personal devices such as traffic lights,
devices in stores they shop in, facilities they work in and so on,
even considering individual light bulbs. A device may have
individually attested subsystems, for example parts of a car or a
mobile phone. It is assumed that the largest database will have at
most 10% of the world’s population of devices. Note that databases
that handle more than a trillion records exist today.The trillion-record database size models an easy-to-imagine reality
over the next decades. The quadrillion-record database is roughly at
the limit of what is imaginable and should probably be accommodated.
The 100 quadrillion datadbase is highly speculative perhaps involving
nanorobots for every person, livestock animal and domesticated
bird. It is included to round out the analysis.Note that the items counted here certainly do not have IP address and
are not individually connected to the network. They may be connected
to internal buses, via serial links, Bluetooth and so on. This is
not the same problem as sizing IP addresses.PeopleDevices / PersonSubsystems / DeviceDatabase PortionDatabase Size10 billion1001010%trillion (10^12)10 billion100,0001010%quadrillion (10^15)100 billion1,000,0001010%100 quadrillion (10^17)This is conceptually similar to the Birthday Problem where m is the
number of possible birthdays, always 365, and k is the number of
people. It is also conceptually similar to the Birthday Attack where
collisions of the output of hash functions are considered.The proper formula for the collision calculation isHowever, for the very large values involved here, this formula requires floating
point precision higher than commonly available in calculators and SW so this
simple approximation is used. See .For this calculation:Database Size128-bit UEID192-bit UEID256-bit UEIDtrillion (10^12)2 * 10^-158 * 10^-355 * 10^-55quadrillion (10^15)2 * 10^-098 * 10^-295 * 10^-49100 quadrillion (10^17)2 * 10^-058 * 10^-255 * 10^-45Next, to calculate the probability of a collision occurring in one year’s
operation of a database, it is assumed that the database size is in
a steady state and that 10% of the database changes per year. For example,
a trillion record database would have 100 billion states per year. Each
of those states has the above calculated probability of a collision.This assumption is a worst-case since it assumes that each
state of the database is completely independent from the previous state.
In reality this is unlikely as state changes will be the addition or
deletion of a few records.The following tables gives the time interval until there is a probability of
a collision based on there being one tenth the number of states per year
as the number of records in the database.Database Size128-bit UEID192-bit UEID256-bit UEIDtrillion (10^12)60,000 years10^24 years10^44 yearsquadrillion (10^15)8 seconds10^14 years10^34 years100 quadrillion (10^17)8 microseconds10^11 years10^31 yearsClearly, 128 bits is enough for the near future thus the requirement that UEIDs
be a minimum of 128 bits.There is no requirement for 256 bits today as quadrillion-record databases
are not expected in the near future and because this time-to-collision
calculation is a very worst case. A future update of the standard may
increase the requirement to 256 bits, so there is a requirement that
implementations be able to receive 256-bit UEIDs.A UEID is not a UUID by conscious choice for the following
reasons.UUIDs are limited to 128 bits which may not be enough for some future
use cases.Today, cryptographic-quality random numbers are available from common
CPUs and hardware. This hardware was introduced between 2010 and 2015.
Operating systems and cryptographic libraries give access to this
hardware. Consequently, there is little need for implementations
to construct such random values from multiple sources on their own.Version 4 UUIDs do allow for use of such cryptographic-quality
random numbers, but do so by mapping into the overall UUID
structure of time and clock values. This structure is of no
value here yet adds complexity. It also slightly reduces the
number of actual bits with entropy.UUIDs seem to have been designed for scenarios where the implementor
does not have full control over the environment and uniqueness has to
be constructed from identifiers at hand. UEID takes the view that
hardware, software and/or manufacturing process directly implement
UEID in a simple and direct way. It takes the view that cryptographic
quality random number generators are readily available as they are
implemented in commonly used CPU hardware.This section describes several distinct ways in which an IEEE IDevID relates to EAT, particularly to UEID and SUEID. orients around the definition of an implementation called a “DevID Module.”
It describes how IDevIDs and LDevIDs are stored, protected and accessed using a DevID Module.
A particular level of defense against attack that should be achieved to be a DevID is defined.
The intent is that IDevIDs and LDevIDs are used with an open set of network protocols for authentication and such.
In these protocols the DevID secret is used to sign a nonce or similar to proof the association of the DevID certificates with the device.By contrast, EAT defines network protocol for proving trustworthiness to a Relying Party, the very thing that is not defined in .
Nor does not give details on how keys, data and such are stored protected and accessed.
EAT is intended to work with a variety of different on-device implementations ranging from minimal protection of assets to the highest levels of asset protection.
It does not define any particular level of defense against attack, instead providing a set of security considerations.EAT and DevID can be viewed as complimentary when used together or as competing to provide a device identity service.As just described, EAT defines a network protocol and doesn’t.
Vice versa, EAT doesn’t define a an device implementation and DevID does.Hence, EAT can be the network protocol that a DevID is used with.
The DevID secret becomes the attestation key used to sign EATs.
The DevID and its certificate chain become the Endorsement sent to the Verifier.In this case the EAT and the DevID are likely to both provide a device identifier (e.g. a serial number).
In the EAT it is the UEID (or SUEID).
In the DevID (used as an endorsement), it is a device serial number included in the subject field of the DevID certificate.
It is probably a good idea in this use for them to be the same serial number or for the UEID to be a hash of the DevID serial number.The UEID, SUEID and other claims like OEM ID are equivalent to the secure device identity put into the subject field of a DevID certificate.
These EAT claims can represent all the same fields and values that can be put in a DevID certificate subject.
EAT explicitly and carefully defines a variety of useful claims.EAT secures the conveyance of these claims by having them signed on the device by the attestation key when the EAT is generated.
EAT also signs the nonce that gives freshness at this time.
Since these claims are signed for every EAT generated, they can include things that vary over time like GPS location.DevID secures the device identity fields by having them signed by the manufacturer of the device sign them into a certificate.
That certificate is created once during the manufacturing of the device and never changes so the fields cannot change.So in one case the signing of the identity happens on the device and the other in a manufacturing facility,
but in both cases the signing of the nonce that proves the binding to the actual device happens on the device.While EAT does not specify how the signing keys, signature process and storage of the identity values should be secured against attack,
an EAT implementation may have equal defenses against attack.
One reason EAT uses CBOR is because it is simple enough that a basic EAT implementation can be constructed entirely in hardware.
This allows EAT to be implemented with the strongest defenses possible.It is possible to define a way to encode EAT claims in an X.509 certificate.
For example, the EAT claims might be mapped to X.509 v3 extensions.
It is even possible to stuff a whole CBOR-encoded unsigned EAT token into a X.509 certificate.If that X.509 certificate is an IDevID or LDevID, this becomes another way to use EAT and DevID together.Note that the DevID must still be used with an authentication protocol that has a nonce or equivalent.
The EAT here is not being used as the protocol to interact with the rely party.In terms of permanence, an IDevID is similar to a UEID in that they do not change over the life of the device.
They cease to exist only when the device is destroyed.An SUEID is similar to an LDevID.
They change on device life-cycle events. describes much of this permanence as resistant to attacks that seek to change the ID.
IDevID permanence can be described this way because is oriented around the definition of an implementation with a particular level of defense against attack.EAT is not defined around a particular implementation and must work on a range of devices that have a range of defenses against attack.
EAT thus can’t be defined permanence in terms of defense against attack.
EAT’s definition of permanence is in terms of operations and device lifecycle.The following is a list of known changes from the previous drafts. This list is
non-authoritative. It is meant to help reviewers see the significant
differences.Added UEID design rationale appendixThis is a fairly large change in the orientation of the document, but
no new claims have been added.Separate information and data model using CDDL.Say an EAT is a CWT or JWTUse a map to structure the boot_state and location claimsClarifications and corrections for OEMID claimMinor spelling and other fixesAdd the nonce claim, clarify jti claimRoll all EUIs back into one UEID typeUEIDs can be one of three lengths, 128, 192 and 256.Added appendix justifying UEID design and size.Submods part now includes nested eat tokens so they can be named and
there can be more tha one of themLots of fixes to the CDDLAdded security considerationsSplit boot_state into secure-boot and debug-disable claimsDebug disable is an enumerated type rather than BooleansChange IMEI-based UEIDs to be encoded as a 14-byte stringCDDL cleaned up some moreCDDL allows for JWTs and UCCSsCWT format submodules are byte string wrappedAllows for JWT nested in CWT and vice versaAllows UCCS (unsigned CWTs) and JWT unsecured tokensClarify tag usage when nesting tokensAdd section on key inclusionAdd hardware version claimsCollected CDDL is now filled in. Other CDDL corrections.Rename debug-disable to debug-status; clarify that it is not extensibleSecurity level claim is not extensibleImprove specification of location claim and added a location privacy sectionAdd intended use claimCDDL format issues resolvedCorrected reference to Location Privacy sectionAdded boot-seed claimRework CBOR interoperability sectionAdded profiles claim and sectionFilled in IANA and other sections for possible preassignment of Claim Keys for well understood claimsChange profile claim to be either a URL or an OID rather than a test stringAdd SUEIDsAdd appendix comparing IDevID to EATAdded section on use for Evidence and Attestation ResultsFill in the key ID and endorsements identificaiton sectionRemove origination claim as it is replaced by key IDs and endorsementsAdded manifests and software evidence claimsAdd string labels non-claim labels for use with JSON (e.g. labels for members of location claim)EAN-13 HW versions are no longer a separate claim. Now they are folded in as a CoSWID version scheme.Hardware version is made into an array of two rather than two claimsCorrections and wording improvements for security levels claimAdd swresults claimAdd dloas claim – Digitial Letter of Approvals, a list of certificationsCDDL for each claim no longer in a separate sub sectionConsistent use of terminology from RATS architecture documentConsistent use of terminology from CWT and JWT documentsRemove operating model and procedures; refer to CWT, JWT and RATS architecture insteadSome reorganization of Section 1Moved a few references, including RATS Architecture, to informative.Add detached submodule digests and detached eat bundles (DEBs)New simpler and more universal scheme for identifying the encoding of a nested tokenMade clear that CBOR and JSON are only mixed when nesting a token in another tokenClearly separate CDDL for JSON and CBOR-specific data itemsDefine UJCS (unsigned JWTs)Add CDDL for a general Claims-Set used by UCCS, UJCS, CWT, JWT and EATTop level CDDL for CWT correctly refers to COSEOEM ID is specifically for HW, not for SWHW OEM ID can now be a PENHW OEM ID can now be a 128-bit random numberExpand the examples sectionAdd software and version claims as easy / JSON alternative to CoSWIDAdd HW model claimChange reference for CBOR OID draft to RFC 9090Correct the iat claim in some examplesMake HW Version just one claim rather than 3 (device, board and chip)Remove CDDL comments from CDDL blocksMore clearly define “entity” and use it more broadly, particularly instead of “device”Re do early allocation of CBOR labels since last one didn’t complete correctlyLots of rewording and tightening up of section 1Lots of wording improvements in section 3, particularly better use of normative languageImprove wording in submodules section, particularly how to distinguish types when decodingRemove security-level from early allocationAdd boot odometer claimAdd privacy considerations for replay protection