A YANG Data Model for Challenge-Response-based Remote Attestation Procedures using TPMs

The YANG Module for Basic Remote Attestation Procedures One or more TPMs MUST be embedded in a Composite Device that provides attestation Evidence via the YANG module defined in this document. The ietf-tpm-remote-attestation YANG module enables a composite device to take on the role of an Attester, in accordance with the Remote Attestation Procedures (RATS) architecture , and the corresponding challenge-response interaction model defined in the document. A fresh nonce with an appropriate amount of entropy MUST be supplied by the YANG client in order to enable a proof-of-freshness with respect to the attestation Evidence provided by the Attester running the YANG datastore. Further, this nonce is used to prevent replay attacks. The method for communicating the relationship of each individual TPM to specific measured component within the Composite Device is out of the scope of this document.

YANG Modules In this section the several YANG modules are defined.

'ietf-tpm-remote-attestation' This YANG module imports modules from with prefix 'yang', with prefix 'hw', with prefix 'ks', and 'ietf-tcg-algs.yang' with prefix 'taa'. Additionally, references are made to , , , , , , , , , , as well as and .

Features This module supports the following features: 'mtpm': Indicates that multiple TPMs on the device can support remote attestation. For example, this feature could be used in cases where multiple line cards are present, each with its own TPM. 'bios': Indicates that the device supports the retrieval of BIOS/UEFI event logs. 'ima': Indicates that the device supports the retrieval of event logs from the Linux Integrity Measurement Architecture (IMA, see ). 'netequip_boot': Indicates that the device supports the retrieval of netequip boot event logs. See and .

Identities This module supports the following types of attestation event logs: 'bios', 'ima', and 'netequip_boot'.

Remote Procedure Calls (RPCs) In the following, RPCs for both TPM 1.2 and TPM 2.0 attestation procedures are defined.

'tpm12-challenge-response-attestation' This RPC allows a Verifier to request signed TPM PCRs (TPM Quote operation) from a TPM 1.2 compliant cryptoprocessor. Where the feature 'mtpm' is active, and one or more 'certificate-name' is not provided, all TPM 1.2 compliant cryptoprocessors will respond. A YANG tree diagram of this RPC is as follows:

'tpm20-challenge-response-attestation' This RPC allows a Verifier to request signed TPM PCRs (TPM Quote operation) from a TPM 2.0 compliant cryptoprocessor. Where the feature 'mtpm' is active, and one or more 'certificate-name' is not provided, all TPM 2.0 compliant cryptoprocessors will respond. A YANG tree diagram of this RPC is as follows:

An example of an RPC challenge requesting PCRs 0-7 from a SHA-256 bank could look like the following:

(identifier of a TPM signature key with which the Attester is supposed to sign the attestation data)

0xe041307208d9f78f5b1bbecd19e2d152ad49de2fc5a7d8dbf769f6b8ffdeab9

TPM_ALG_SHA256

]]> A successful response could be formatted as follows:

(instance of Certificate name in the Keystore)

(raw attestation data, i.e., the TPM quote; this includes, among other information, a composite digest of requested PCRs, the nonce, and TPM 2.0 clock information.)

(signature over attestation-data using the TPM key identified by sig-key-id)

]]>

'log-retrieval' This RPC allows a Verifier to acquire the Evidence which was extended into specific TPM PCRs. A YANG tree diagram of this RPC is as follows:

Data Nodes This section provides a high level description of the data nodes containing the configuration and operational objects with the YANG model. For more details, please see the YANG model itself in .

Container 'rats-support-structures':: This houses the set of information relating to remote attestation for a device. This includes specific device TPM(s), the compute nodes (such as line cards) on which the TPM(s) reside, and the algorithms supported across the platform.
Container 'tpms':: Provides configuration and operational details for each supported TPM, including the tpm-firmware-version, PCRs which may be quoted, certificates which are associated with that TPM, and the current operational status. Of note are the certificates which are associated with that TPM. As a certificate is associated with a particular TPM attestation key, knowledge of the certificate allows a specific TPM to be identified.

container 'attester-supported-algos' - Identifies which TCG hash algorithms are available for use on the Attesting platform. An operator will use this information to limit algorithms available for use by RPCs to just a desired set from the universe of all allowed hash algorithms by the TCG.

container 'compute-nodes' - When there is more than one TPM supported, this container maintains the set of information related to the compute node associated with a specific TPM. This allows each specific TPM to identify to which 'compute-node' it belongs.

YANG Module

file "ietf-tpm-remote-attestation.yang" module ietf-tpm-remote-attestation { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-tpm-remote-attestation"; prefix tpm; import ietf-yang-types { prefix yang; } import ietf-hardware { prefix hw; } import ietf-keystore { prefix ks; } import ietf-tcg-algs { prefix taa; } organization "IETF RATS (Remote ATtestation procedureS) Working Group"; contact "WG Web : WG List : Author : Eric Voit Author : Henk Birkholz Author : Michael Eckel Author : Shwetha Bhandari Author : Bill Sulzen Author : Liang Xia (Frank) Author : Tom Laffey Author : Guy Fedorkow "; description "A YANG module to enable a TPM 1.2 and TPM 2.0 based remote attestation procedure using a challenge-response interaction model and the TPM 1.2 and TPM 2.0 Quote primitive operations. Copyright (c) 2022 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Revised BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself for full legal notices. 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 (RFC 2119) (RFC 8174) when, and only when, they appear in all capitals, as shown here."; revision 2022-05-17 { description "Initial version"; reference "RFC XXXX: A YANG Data Model for Challenge-Response-based Remote Attestation Procedures using TPMs"; } /*****************/ /* Features */ /*****************/ feature mtpm { description "The device supports the remote attestation of multiple TPM based cryptoprocessors."; } feature bios { description "The device supports the bios logs."; reference "bios-log: https://trustedcomputinggroup.org/wp-content/uploads/ PC-ClientSpecific_Platform_Profile_for_TPM_2p0_Systems_v51.pdf Section 9.4.5.2"; } feature ima { description "The device supports Integrity Measurement Architecture logs. Many variants of IMA logs exist in the deployment. Each encodes the log entry contents as the specific measurements which get hashed into a PCRs as Evidence. See the reference below for one example of such an encoding."; reference "ima-log: https://www.trustedcomputinggroup.org/wp-content/uploads/ TCG_IWG_CEL_v1_r0p41_pub.pdf Section 5.1.6"; } feature netequip_boot { description "The device supports the netequip_boot logs."; reference "netequip-boot-log: RFC XXXX Appendix B"; } /*****************/ /* Typedefs */ /*****************/ typedef pcr { type uint8 { range "0..31"; } description "Valid index number for a PCR. A {{TPM2.0}} compliant PCR index extends from 0-31. At this time a typical TPM would have no more than 32 PCRS."; } typedef compute-node-ref { type leafref { path "/tpm:rats-support-structures/tpm:compute-nodes" + "/tpm:compute-node/tpm:node-id"; } description "This type is used to reference a hardware node. Note that an implementer might include an alternative leafref pointing to a different YANG module node specifying hardware structures."; } typedef certificate-name-ref { type leafref { path "/tpm:rats-support-structures/tpm:tpms/tpm:tpm" + "/tpm:certificates/tpm:certificate/tpm:name"; } description "A type which allows identification of a TPM based certificate."; } /******************/ /* Identities */ /******************/ identity attested_event_log_type { description "Base identity allowing categorization of the reasons why an attested measurement has been taken on an Attester."; } identity ima { base attested_event_log_type; description "An event type recorded in IMA."; } identity bios { base attested_event_log_type; description "An event type associated with BIOS/UEFI."; } identity netequip_boot { base attested_event_log_type; description "An event type associated with Network Equipment Boot."; } /*****************/ /* Groupings */ /*****************/ grouping tpm20-hash-algo { description "The cryptographic algorithm used to hash the TPM2 PCRs. This must be from the list of platform supported options."; leaf tpm20-hash-algo { type identityref { base taa:hash; } must '. = /tpm:rats-support-structures' + '/tpm:attester-supported-algos/tpm:tpm20-hash' { error-message "This platform does not support tpm20-hash-algo"; } description "The hash scheme that is used to hash a TPM2.0 PCR. This must be one of those supported by a platform. Where this object does not appear, the default value of 'taa:TPM_ALG_SHA256' will apply."; } } grouping tpm12-hash-algo { description "The cryptographic algorithm used to hash the TPM1.2 PCRs."; leaf tpm12-hash-algo { type identityref { base taa:hash; } must '. = /tpm:rats-support-structures' + '/tpm:attester-supported-algos/tpm:tpm12-hash' { error-message "This platform does not support tpm12-hash-algo"; } description "The hash scheme that is used to hash a TPM1.2 PCR. This MUST be one of those supported by a platform. Where this object does not appear, the default value of 'taa:TPM_ALG_SHA1' will apply."; } } grouping nonce { description "A random number intended to guarantee freshness and for use as part of a replay-detection mechanism."; leaf nonce-value { type binary; mandatory true; description "A cryptographically generated random number which should not be predictable prior to its issuance from a random number generation function. The random number MUST be derived from an entropy source external to the Attester. Note that a nonce sent into a TPM will typically be 160 or 256 binary digits long. (This is 20 or 32 bytes.) So if fewer binary digits are sent, this nonce object will be padded with leading zeros within Quotes returned from the TPM. Additionally if more bytes are sent, the nonce will be trimmed to the most significant binary digits."; } } grouping tpm12-pcr-selection { description "A Verifier can request one or more PCR values using its individually created Attestation Key Certificate (AC). The corresponding selection filter is represented in this grouping."; leaf-list pcr-index { type pcr; description "The numbers/indexes of the PCRs. In addition, any selection of PCRs MUST verify that the set of PCRs requested are a subset the set of PCRs exposed by in the leaf-list /tpm:rats-support-structures /tpm:tpms/tpm:tpm[name=current()]/tpm:tpm12-pcrs"; } } grouping tpm20-pcr-selection { description "A Verifier can acquire one or more PCR values, which are hashed together in a TPM2B_DIGEST coming from the TPM2. The selection list of desired PCRs and the Hash Algorithm is represented in this grouping."; list tpm20-pcr-selection { unique "tpm20-hash-algo"; description "Specifies the list of PCRs and Hash Algorithms that can be returned within a TPM2B_DIGEST."; reference "TPM2.0-Structures: https://www.trustedcomputinggroup.org/wp-content/uploads/ TPM-Rev-2.0-Part-2-Structures-01.38.pdf Section 10.9.7"; uses tpm20-hash-algo; leaf-list pcr-index { type pcr; description "The numbers of the PCRs that which are being tracked with a hash based on the tpm20-hash-algo. In addition, any selection of PCRs MUST verify that the set of PCRs requested are a subset the set of PCR indexes selected are available for that specific TPM."; } } } grouping certificate-name-ref { description "Identifies a certificate in a keystore."; leaf certificate-name { type certificate-name-ref; mandatory true; description "Identifies a certificate in a keystore."; } } grouping tpm-name { description "A unique TPM on a device."; leaf name { type string; description "Unique system generated name for a TPM on a device."; } } grouping node-uptime { description "Uptime in seconds of the node."; leaf up-time { type uint32; description "Uptime in seconds of this node reporting its data"; } } grouping tpm12-attestation { description "Contains an instance of TPM1.2 style signed cryptoprocessor measurements. It is supplemented by unsigned Attester information."; uses node-uptime; leaf pcr-data { type binary; description "The value created and signed for the quote (type TPM_PCR_INFO_SHORT), i.e., the 'pcrData' part of a TPM1.2 Quote2 operation result."; reference "TPM1.2-Commands: TPM1.2 commands rev116 July 2007, Section 16.5 https://trustedcomputinggroup.org/wp-content/uploads /TPM-Main-Part-3-Commands_v1.2_rev116_01032011.pdf"; } leaf version-info { type binary; description "The version info (type TPM_CAP_VERSION_INFO), i.e., the 'versionInfo' part of a TPM1.2 Quote2 operation result."; reference "TPM1.2-Commands: TPM1.2 commands rev116 July 2007, Section 16.5 https://trustedcomputinggroup.org/wp-content/uploads /TPM-Main-Part-3-Commands_v1.2_rev116_01032011.pdf"; } leaf sig { type binary; description "The signed data blob, i.e., the signature i.e., the 'sig' part of a TPM1.2 Quote2 operation result."; reference "TPM1.2-Commands: TPM1.2 commands rev116 July 2007, Section 16.5 https://trustedcomputinggroup.org/wp-content/uploads /TPM-Main-Part-3-Commands_v1.2_rev116_01032011.pdf"; } } grouping tpm20-attestation { description "Contains an instance of TPM2 style signed cryptoprocessor measurements. It is supplemented by unsigned Attester information."; leaf quote-data { type binary; mandatory true; description "A hash of the latest PCR values (and the hash algorithm used) which have been returned from an Attester for the selected PCRs and Hash Algorithms."; reference "TPM2.0-Structures: https://www.trustedcomputinggroup.org/wp-content/uploads/ TPM-Rev-2.0-Part-2-Structures-01.38.pdf Section 10.12.1"; } leaf quote-signature { type binary; description "Quote signature returned by TPM Quote. The signature was generated using the key associated with the certificate 'name'."; reference "TPM2.0-Structures: https://www.trustedcomputinggroup.org/wp-content/uploads/ TPM-Rev-2.0-Part-2-Structures-01.38.pdf Section 11.2.1"; } uses node-uptime; list unsigned-pcr-values { description "PCR values in each PCR bank. This might appear redundant with the TPM2B_DIGEST, but that digest is calculated across multiple PCRs. Having to verify across multiple PCRs does not necessarily make it easy for a Verifier to appraise just the minimum set of PCR information which has changed since the last received TPM2B_DIGEST. Put another way, why should a Verifier reconstruct the proper value of all PCR Quotes when only a single PCR has changed? To help this happen, if the Attester does know specific PCR values, the Attester can provide these individual values via 'unsigned-pcr-values'. By comparing this information to what has previously been validated, it is possible for a Verifier to confirm the Attester's signature while eliminating significant processing. Note that there should never be a result where an unsigned PCR value differs from what may be reconstructed from the within the PCR quote and the event logs. If there is a difference, a signed result which has been verified from retrieved logs is considered definitive."; uses tpm20-hash-algo; list pcr-values { key "pcr-index"; description "List of one PCR bank."; leaf pcr-index { type pcr; description "PCR index number."; } leaf pcr-value { type binary; description "PCR value."; reference "TPM2.0-Structures: https://www.trustedcomputinggroup.org/wp-content/uploads/ TPM-Rev-2.0-Part-2-Structures-01.38.pdf Section 10.9.7"; } } } } grouping log-identifier { description "Identifier for type of log to be retrieved."; leaf log-type { type identityref { base attested_event_log_type; } mandatory true; description "The corresponding measurement log type identity."; } } grouping boot-event-log { description "Defines a specific instance of an event log entry and corresponding to the information used to extend the PCR"; leaf event-number { type uint32; description "Unique event number of this event which monotonically increases within a given event log. The maximum event number should not be reached, nor is wrapping back to an earlier number supported."; } leaf event-type { type uint32; description "BIOS Log Event Type: https://trustedcomputinggroup.org/wp-content/uploads/ TCG_PCClient_PFP_r1p05_v23_pub.pdf Section 10.4.1"; } leaf pcr-index { type pcr; description "Defines the PCR index that this event extended"; } list digest-list { description "Hash of event data"; leaf hash-algo { type identityref { base taa:hash; } description "The hash scheme that is used to compress the event data in each of the leaf-list digest items."; } leaf-list digest { type binary; description "The hash of the event data using the algorithm of the 'hash-algo' against 'event data'."; } } leaf event-size { type uint32; description "Size of the event data"; } leaf-list event-data { type binary; description "The event data. This is a binary structure of size 'event-size'. For more on what might be recorded within this object see [bios-log] Section 9 which details viable events which might be recorded."; } } grouping bios-event-log { description "Measurement log created by the BIOS/UEFI."; list bios-event-entry { key "event-number"; description "Ordered list of TCG described event log that extended the PCRs in the order they were logged"; uses boot-event-log; } } grouping ima-event { description "Defines a hash log extend event for IMA measurements"; reference "ima-log: https://www.trustedcomputinggroup.org/wp-content/uploads/ TCG_IWG_CEL_v1_r0p41_pub.pdf Section 4.3"; leaf event-number { type uint64; description "Unique event number of this event which monotonically increases. The maximum event number should not be reached, nor is wrapping back to an earlier number supported."; } leaf ima-template { type string; description "Name of the template used for event logs for e.g. ima, ima-ng, ima-sig"; } leaf filename-hint { type string; description "File name (including the path) that was measured."; } leaf filedata-hash { type binary; description "Hash of filedata as updated based upon the filedata-hash-algorithm"; } leaf filedata-hash-algorithm { type string; description "Algorithm used for filedata-hash"; } leaf template-hash-algorithm { type string; description "Algorithm used for template-hash"; } leaf template-hash { type binary; description "hash(filedata-hash, filename-hint)"; } leaf pcr-index { type pcr; description "Defines the PCR index that this event extended"; } leaf signature { type binary; description "Digital file signature which provides a fingerprint for the file being measured."; } } grouping ima-event-log { description "Measurement log created by IMA."; list ima-event-entry { key "event-number"; description "Ordered list of ima event logs by event-number"; uses ima-event; } } grouping network-equipment-boot-event-log { description "Measurement log created by Network Equipment Boot. The Network Equipment Boot format is identical to the IMA format. In contrast to the IMA log, the Network Equipment Boot log includes every measurable event from an Attester, including the boot stages of BIOS, Bootloader, etc. In essence, the scope of events represented in this format combines the scope of BIOS events and IMA events."; list boot-event-entry { key "event-number"; description "Ordered list of Network Equipment Boot event logs by event-number, using the IMA event format."; uses ima-event; } } grouping event-logs { description "A selector for the log and its type."; choice attested_event_log_type { mandatory true; description "Event log type determines the event logs content."; case bios { if-feature "bios"; description "BIOS/UEFI event logs"; container bios-event-logs { description "BIOS/UEFI event logs"; uses bios-event-log; } } case ima { if-feature "ima"; description "IMA event logs."; container ima-event-logs { description "IMA event logs."; uses ima-event-log; } } case netequip_boot { if-feature "netequip_boot"; description "Network Equipment Boot event logs"; container boot-event-logs { description "Network equipment boot event logs."; uses network-equipment-boot-event-log; } } } } /**********************/ /* RPC operations */ /**********************/ rpc tpm12-challenge-response-attestation { if-feature "taa:tpm12"; description "This RPC accepts the input for TSS TPM 1.2 commands made to the attesting device."; input { container tpm12-attestation-challenge { description "This container includes every information element defined in the reference challenge-response interaction model for remote attestation. Corresponding values are based on TPM 1.2 structure definitions"; uses tpm12-pcr-selection; uses nonce; leaf-list certificate-name { if-feature "tpm:mtpm"; type certificate-name-ref; must "/tpm:rats-support-structures/tpm:tpms" + "/tpm:tpm[tpm:firmware-version='taa:tpm12']" + "/tpm:certificates/" + "/tpm:certificate[name=current()]" { error-message "Not an available TPM1.2 AIK certificate."; } description "When populated, the RPC will only get a Quote for the TPMs associated with these certificate(s)."; } } } output { list tpm12-attestation-response { unique "certificate-name"; description "The binary output of TPM 1.2 TPM_Quote/TPM_Quote2, including the PCR selection and other associated attestation evidence metadata"; uses certificate-name-ref { description "Certificate associated with this tpm12-attestation."; } uses tpm12-attestation; } } } rpc tpm20-challenge-response-attestation { if-feature "taa:tpm20"; description "This RPC accepts the input for TSS TPM 2.0 commands of the managed device. ComponentIndex from the hardware manager YANG module is used to refer to dedicated TPM in composite devices, e.g. smart NICs, is not covered."; input { container tpm20-attestation-challenge { description "This container includes every information element defined in the reference challenge-response interaction model for remote attestation. Corresponding values are based on TPM 2.0 structure definitions"; uses nonce; uses tpm20-pcr-selection; leaf-list certificate-name { if-feature "tpm:mtpm"; type certificate-name-ref; must "/tpm:rats-support-structures/tpm:tpms" + "/tpm:tpm[tpm:firmware-version='taa:tpm20']" + "/tpm:certificates/" + "/tpm:certificate[name=current()]" { error-message "Not an available TPM2.0 AIK certificate."; } description "When populated, the RPC will only get a Quote for the TPMs associated with the certificates."; } } } output { list tpm20-attestation-response { unique "certificate-name"; description "The binary output of TPM2_Quote from one TPM of the node which identified by node-id. An TPMS_ATTEST structure including a length, encapsulated in a signature"; uses certificate-name-ref { description "Certificate associated with this tpm20-attestation."; } uses tpm20-attestation; } } } rpc log-retrieval { description "Logs Entries are either identified via indices or via providing the last line received. The number of lines returned can be limited. The type of log is a choice that can be augmented."; input { uses log-identifier; list log-selector { description "Only log entries which meet all the selection criteria provided are to be returned by the RPC output."; leaf-list name { type string; description "Name of one or more unique TPMs on a device. If this object exists, a selection should pull only the objects related to these TPM(s). If it does not exist, all qualifying TPMs that are 'hardware-based' equals true on the device are selected. When this selection criteria is provided, it will be considered as a logical AND with any other selection criteria provided."; } choice index-type { description "Last log entry received, log index number, or timestamp."; case last-entry { description "The last entry of the log already retrieved."; leaf last-entry-value { type binary; description "Content of a log event which matches 1:1 with a unique event record contained within the log. Log entries after this will be passed to the requester. Note: if log entry values are not unique, this MUST return an error."; } } case index { description "Numeric index of the last log entry retrieved, or zero."; leaf last-index-number { type uint64; description "The last numeric index number of a log entry. Zero means to start at the beginning of the log. Entries after this will be passed to the requester."; } } case timestamp { leaf timestamp { type yang:date-and-time; description "Timestamp from which to start the extraction. The next log entry after this timestamp is to be sent."; } description "Timestamp from which to start the extraction."; } } leaf log-entry-quantity { type uint16; description "The number of log entries to be returned. If omitted, it means all of them."; } } } output { container system-event-logs { description "The requested data of the measurement event logs"; list node-data { unique "name"; description "Event logs of a node in a distributed system identified by the node name"; uses tpm-name; uses node-uptime; container log-result { description "The requested entries of the corresponding log."; uses event-logs; } } } } } /**************************************/ /* Config & Oper accessible nodes */ /**************************************/ container rats-support-structures { description "The datastore definition enabling verifiers or relying parties to discover the information necessary to use the remote attestation RPCs appropriately."; container compute-nodes { if-feature "tpm:mtpm"; description "Holds the set of device subsystems/components in this composite device that support TPM operations."; list compute-node { key "node-id"; unique "node-name"; config false; min-elements 2; description "A component within this composite device which supports TPM operations."; leaf node-id { type string; description "ID of the compute node, such as Board Serial Number."; } leaf node-physical-index { if-feature "hw:entity-mib"; type int32 { range "1..2147483647"; } config false; description "The entPhysicalIndex for the compute node."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalIndex"; } leaf node-name { type string; description "Name of the compute node."; } leaf node-location { type string; description "Location of the compute node, such as slot number."; } } } container tpms { description "Holds the set of TPMs within an Attester."; list tpm { key "name"; unique "path"; description "A list of TPMs in this composite device that RATS can be conducted with."; uses tpm-name; leaf hardware-based { type boolean; config false; mandatory true; description "System generated indication of whether this is a hardware based TPM."; } leaf physical-index { if-feature "hw:entity-mib"; type int32 { range "1..2147483647"; } config false; description "The entPhysicalIndex for the TPM."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalIndex"; } leaf path { type string; config false; description "Device path to a unique TPM on a device. This can change across reboots."; } leaf compute-node { if-feature "tpm:mtpm"; type compute-node-ref; config false; mandatory true; description "Indicates the compute node measured by this TPM."; } leaf manufacturer { type string; config false; description "TPM manufacturer name."; } leaf firmware-version { type identityref { base taa:cryptoprocessor; } mandatory true; description "Identifies the cryptoprocessor API set supported. This is automatically configured by the device and should not be changed."; } uses tpm12-hash-algo { when "derived-from-or-self(firmware-version, 'taa:tpm12')"; if-feature "taa:tpm12"; refine "tpm12-hash-algo" { description "The hash algorithm overwrites the default used for PCRs on this TPM1.2 compliant cryptoprocessor."; } } leaf-list tpm12-pcrs { when "derived-from-or-self(../firmware-version, 'taa:tpm12')"; if-feature "taa:tpm12"; type pcr; description "The PCRs which may be extracted from this TPM1.2 compliant cryptoprocessor."; } list tpm20-pcr-bank { when "derived-from-or-self(../firmware-version, 'taa:tpm20')"; if-feature "taa:tpm20"; key "tpm20-hash-algo"; description "Specifies the list of PCRs that may be extracted for a specific Hash Algorithm on this TPM2 compliant cryptoprocessor. A bank is a set of PCRs which are extended using a particular hash algorithm."; reference "TPM2.0-Structures: https://www.trustedcomputinggroup.org/wp-content/uploads/ TPM-Rev-2.0-Part-2-Structures-01.38.pdf Section 10.9.7"; leaf tpm20-hash-algo { type identityref { base taa:hash; } must '/tpm:rats-support-structures' + '/tpm:attester-supported-algos' + '/tpm:tpm20-hash' { error-message "This platform does not support tpm20-hash-algo"; } description "The hash scheme actively being used to hash a one or more TPM2.0 PCRs."; } leaf-list pcr-index { type tpm:pcr; description "Defines what TPM2 PCRs are available to be extracted."; } } leaf status { type enumeration { enum operational { value 0; description "The TPM currently is running normally and is ready to accept and process TPM quotes."; reference "TPM2.0-Arch: https://trustedcomputinggroup.org/wp-content/uploads/ TCG_TPM2_r1p59_Part1_Architecture_pub.pdf Section 12"; } enum non-operational { value 1; description "TPM is in a state such as startup or shutdown which precludes the processing of TPM quotes."; } } config false; mandatory true; description "TPM chip self-test status."; } container certificates { description "The TPM's certificates, including EK certificates and Attestation Key certificates."; list certificate { key "name"; description "Three types of certificates can be accessed via this statement, including Initial Attestation Key Certificate, Local Attestation Key Certificate or Endorsement Key Certificate."; leaf name { type string; description "An arbitrary name uniquely identifying a certificate associated within key within a TPM."; } leaf keystore-ref { if-feature "ks:central-keystore-supported"; if-feature "ks:asymmetric-keys"; type leafref { path "/ks:keystore/ks:asymmetric-keys/ks:asymmetric-key" + "/ks:name"; } description "A reference to a specific certificate of an asymmetric key in the Keystore."; } leaf type { type enumeration { enum endorsement-certificate { value 0; description "Endorsement Key (EK) Certificate type."; reference "TPM2.0-Key: https://trustedcomputinggroup.org/wp-content/ uploads/TPM-2p0-Keys-for-Device-Identity- and-Attestation_v1_r12_pub10082021.pdf Section 3.11"; } enum initial-attestation-certificate { value 1; description "Initial Attestation key (IAK) Certificate type."; reference "TPM2.0-Key: https://trustedcomputinggroup.org/wp-content/ uploads/TPM-2p0-Keys-for-Device-Identity- and-Attestation_v1_r12_pub10082021.pdf Section 3.2"; } enum local-attestation-certificate { value 2; description "Local Attestation Key (LAK) Certificate type."; reference "TPM2.0-Key: https://trustedcomputinggroup.org/wp-content/ uploads/TPM-2p0-Keys-for-Device-Identity- and-Attestation_v1_r12_pub10082021.pdf Section 3.2"; } } description "Function supported by this certificate from within the TPM."; } } } } } container attester-supported-algos { description "Identifies which TPM algorithms are available for use on an attesting platform."; leaf-list tpm12-asymmetric-signing { when "../../tpm:tpms" + "/tpm:tpm[tpm:firmware-version='taa:tpm12']"; if-feature "taa:tpm12"; type identityref { base taa:asymmetric; } description "Platform Supported TPM12 asymmetric algorithms."; } leaf-list tpm12-hash { when "../../tpm:tpms" + "/tpm:tpm[tpm:firmware-version='taa:tpm12']"; if-feature "taa:tpm12"; type identityref { base taa:hash; } description "Platform supported TPM12 hash algorithms."; } leaf-list tpm20-asymmetric-signing { when "../../tpm:tpms" + "/tpm:tpm[tpm:firmware-version='taa:tpm20']"; if-feature "taa:tpm20"; type identityref { base taa:asymmetric; } description "Platform Supported TPM20 asymmetric algorithms."; } leaf-list tpm20-hash { when "../../tpm:tpms" + "/tpm:tpm[tpm:firmware-version='taa:tpm20']"; if-feature "taa:tpm20"; type identityref { base taa:hash; } description "Platform supported TPM20 hash algorithms."; } } } }

]]>


'ietf-tcg-algs'

This document has encoded the TCG Algorithm definitions of , revision 1.32. By including this full table as a separate YANG file within this document, it is possible for other YANG models to leverage the contents of this model. Specific references to , , , , , , , , , , , , , , , , , , as well as  and  exist within the YANG Model.

Features

There are two types of features supported: 'TPM12' and 'TPM20'. Support for either of these features indicates that a cryptoprocessor supporting the corresponding type of TCG TPM API is present on an Attester. Most commonly, only one type of cryptoprocessor will be available on an Attester.


Identities

There are three types of identities in this model:


  Cryptographic functions supported by a TPM algorithm; these include: 'asymmetric', 'symmetric', 'hash', 'signing', 'anonymous_signing', 'encryption_mode', 'method', and 'object_type'. The definitions of each of these are in Table 2 of .
  API specifications for TPM types: 'tpm12' and 'tpm20'
  Specific algorithm types: Each algorithm type defines what cryptographic functions may be supported, and on which type of API specification. It is not required that an implementation of a specific TPM will support all algorithm types. The contents of each specific algorithm mirrors what is in Table 3 of .



YANG Module

 file "ietf-tcg-algs@2022-03-23.yang"
module ietf-tcg-algs {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-tcg-algs";
  prefix taa;

  organization
    "IETF RATS (Remote ATtestation procedureS) Working Group";
  contact
    "WG Web:   
     WG List:  
     Author:   Eric Voit ";
  description
    "This module defines identities for asymmetric algorithms.

     Copyright (c) 2022 IETF Trust and the persons identified as
     authors of the code. All rights reserved.
     Redistribution and use in source and binary forms, with
     or without modification, is permitted pursuant to, and
     subject to the license terms contained in, the Revised
     BSD License set forth in Section 4.c of the IETF Trust's
     Legal Provisions Relating to IETF Documents
     (https://trustee.ietf.org/license-info).
     
     This version of this YANG module is part of RFC XXXX
     (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself 
     for full legal notices.
     
     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 (RFC 2119)
     (RFC 8174) when, and only when, they appear in all
     capitals, as shown here.";

  revision 2022-03-23 {
    description
      "Initial version";
    reference
      "RFC XXXX: A YANG Data Model for Challenge-Response-based Remote
       Attestation Procedures using TPMs";
  }

  /*****************/
  /*   Features    */
  /*****************/

  feature tpm12 {
    description
      "This feature indicates algorithm support for the TPM 1.2 API
       as per Section 4.8 of TPM1.2-Structures:
       TPM Main Part 2 TPM Structures
       https://trustedcomputinggroup.org/wp-content/uploads/TPM-
       Main-Part-2-TPM-Structures_v1.2_rev116_01032011.pdf";
  }

  feature tpm20 {
    description
      "This feature indicates algorithm support for the TPM 2.0 API
       as per Section 11.4 of Trusted Platform Module Library
       Part 1: Architecture. See TPM2.0-Arch:
       https://trustedcomputinggroup.org/wp-content/uploads/
       TCG_TPM2_r1p59_Part1_Architecture_pub.pdf";
  }

  /*****************/
  /*  Identities   */
  /*****************/

  identity asymmetric {
    description
      "A TCG recognized asymmetric algorithm with a public and
       private key.";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 2,
       https://trustedcomputinggroup.org/resource/
       tcg-algorithm-registry/TCG-_Algorithm_Registry_r1p32_pub";
  }

  identity symmetric {
    description
      "A TCG recognized symmetric algorithm with only a private key.";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 2";
  }

  identity hash {
    description
      "A TCG recognized hash algorithm that compresses input data to
       a digest value or indicates a method that uses a hash.";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 2";
  }

  identity signing {
    description
      "A TCG recognized signing algorithm";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 2";
  }

  identity anonymous_signing {
    description
      "A TCG recognized anonymous signing algorithm.";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 2";
  }

  identity encryption_mode {
    description
      "A TCG recognized encryption mode.";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 2";
  }

  identity method {
    description
      "A TCG recognized method such as a mask generation function.";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 2";
  }

  identity object_type {
    description
      "A TCG recognized object type.";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 2";
  }

  identity cryptoprocessor {
    description
      "Base identity identifying a crytoprocessor.";
  }

  identity tpm12 {
    if-feature "tpm12";
    base cryptoprocessor;
    description
      "Supportable by a TPM1.2.";
    reference
      "TPM1.2-Structures:
       https://trustedcomputinggroup.org/wp-content/uploads/
       TPM-Main-Part-2-TPM-Structures_v1.2_rev116_01032011.pdf
       TPM_ALGORITHM_ID values, Section 4.8";
  }

  identity tpm20 {
    if-feature "tpm20";
    base cryptoprocessor;
    description
      "Supportable by a TPM2.";
    reference
      "TPM2.0-Structures:
       https://trustedcomputinggroup.org/wp-content/uploads/
       TPM-Rev-2.0-Part-2-Structures-01.38.pdf";
  }

  identity TPM_ALG_RSA {
    if-feature "tpm12 or tpm20";
    base tpm12;
    base tpm20;
    base asymmetric;
    base object_type;
    description
      "RSA algorithm";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       RFC 8017. ALG_ID: 0x0001";
  }

  identity TPM_ALG_TDES {
    if-feature "tpm12";
    base tpm12;
    base symmetric;
    description
      "Block cipher with various key sizes (Triple Data Encryption
       Algorithm, commonly called Triple Data Encryption Standard)
       Note: was banned in TPM1.2 v94";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       ISO/IEC 18033-3. ALG_ID: 0x0003";
  }

  identity TPM_ALG_SHA1 {
    if-feature "tpm12 or tpm20";
    base hash;
    base tpm12;
    base tpm20;
    description
      "SHA1 algorithm - Deprecated due to insufficient cryptographic
       protection.  However, it is still useful for hash algorithms
       where protection is not required.";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       ISO/IEC 10118-3. ALG_ID: 0x0004";
  }

  identity TPM_ALG_HMAC {
    if-feature "tpm12 or tpm20";
    base tpm12;
    base tpm20;
    base hash;
    base signing;
    description
      "Hash Message Authentication Code (HMAC) algorithm";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3,
       ISO/IEC 9797-2 and RFC2104. ALG_ID: 0x0005";
  }

  identity TPM_ALG_AES {
    if-feature "tpm12";
    base tpm12;
    base symmetric;
    description
      "The AES algorithm with various key sizes";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3,
       ISO/IEC 18033-3. ALG_ID: 0x0006";
  }

  identity TPM_ALG_MGF1 {
    if-feature "tpm20";
    base tpm20;
    base hash;
    base method;
    description
      "hash-based mask-generation function";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3,
       IEEE Std 1363-2000 and IEEE Std 1363a-2004.
       ALG_ID: 0x0007";
  }

  identity TPM_ALG_KEYEDHASH {
    if-feature "tpm20";
    base tpm20;
    base hash;
    base object_type;
    description
      "An encryption or signing algorithm using a keyed hash.  These
       may use XOR for encryption or an HMAC for signing and may
       also refer to a data object that is neither signing nor
       encrypting.";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3,
       ALG_ID: 0x0008";
  }

  identity TPM_ALG_XOR {
    if-feature "tpm12 or tpm20";
    base tpm12;
    base tpm20;
    base hash;
    base symmetric;
    description
      "The XOR encryption algorithm.";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3.
       ALG_ID: 0x000A";
  }

  identity TPM_ALG_SHA256 {
    if-feature "tpm20";
    base tpm20;
    base hash;
    description
      "The SHA 256 algorithm";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       ISO/IEC 10118-3. ALG_ID: 0x000B";
  }

  identity TPM_ALG_SHA384 {
    if-feature "tpm20";
    base tpm20;
    base hash;
    description
      "The SHA 384 algorithm";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       ISO/IEC 10118-3. ALG_ID: 0x000C";
  }

  identity TPM_ALG_SHA512 {
    if-feature "tpm20";
    base tpm20;
    base hash;
    description
      "The SHA 512 algorithm";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       ISO/IEC 10118-3. ALG_ID: 0x000D";
  }

  identity TPM_ALG_NULL {
    if-feature "tpm20";
    base tpm20;
    description
      "NULL algorithm";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3.
       ALG_ID: 0x0010";
  }

  identity TPM_ALG_SM3_256 {
    if-feature "tpm20";
    base tpm20;
    base hash;
    description
      "The SM3 hash algorithm.";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       ISO/IEC 10118-3:2018. ALG_ID: 0x0012";
  }

  identity TPM_ALG_SM4 {
    if-feature "tpm20";
    base tpm20;
    base symmetric;
    description
      "SM4 symmetric block cipher";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3.
       ALG_ID: 0x0013";
  }

  identity TPM_ALG_RSASSA {
    if-feature "tpm20";
    base tpm20;
    base asymmetric;
    base signing;
    description
      "RFC 8017 Signature algorithm defined in section 8.2
       (RSASSAPKCS1-v1_5)";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       RFC 8017.  ALG_ID: 0x0014";
  }

  identity TPM_ALG_RSAES {
    if-feature "tpm20";
    base tpm20;
    base asymmetric;
    base encryption_mode;
    description
      "RFC 8017 Signature algorithm defined in section 7.2
       (RSAES-PKCS1-v1_5)";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       RFC 8017. ALG_ID: 0x0015";
  }

  identity TPM_ALG_RSAPSS {
    if-feature "tpm20";
    base tpm20;
    base asymmetric;
    base signing;
    description
      "Padding algorithm defined in section 8.1 (RSASSA PSS)";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       RFC 8017. ALG_ID: 0x0016";
  }

  identity TPM_ALG_OAEP {
    if-feature "tpm20";
    base tpm20;
    base asymmetric;
    base encryption_mode;
    description
      "Padding algorithm defined in section 7.1 (RSASSA OAEP)";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       RFC 8017. ALG_ID: 0x0017";
  }

  identity TPM_ALG_ECDSA {
    if-feature "tpm20";
    base tpm20;
    base asymmetric;
    base signing;
    description
      "Signature algorithm using elliptic curve cryptography (ECC)";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       ISO/IEC 14888-3. ALG_ID: 0x0018";
  }

  identity TPM_ALG_ECDH {
    if-feature "tpm20";
    base tpm20;
    base asymmetric;
    base method;
    description
      "Secret sharing using ECC";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       NIST SP800-56A. ALG_ID: 0x0019";
  }

  identity TPM_ALG_ECDAA {
    if-feature "tpm20";
    base tpm20;
    base asymmetric;
    base signing;
    base anonymous_signing;
    description
      "Elliptic-curve based anonymous signing scheme";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       TCG TPM 2.0 library specification. ALG_ID: 0x001A";
  }

  identity TPM_ALG_SM2 {
    if-feature "tpm20";
    base tpm20;
    base asymmetric;
    base signing;
    base encryption_mode;
    base method;
    description
      "SM2 - depending on context, either an elliptic-curve based,
       signature algorithm, an encryption scheme, or a key exchange
       protocol";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3.
       ALG_ID: 0x001B";
  }

  identity TPM_ALG_ECSCHNORR {
    if-feature "tpm20";
    base tpm20;
    base asymmetric;
    base signing;
    description
      "Elliptic-curve based Schnorr signature";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3.
       ALG_ID: 0x001C";
  }

  identity TPM_ALG_ECMQV {
    if-feature "tpm20";
    base tpm20;
    base asymmetric;
    base method;
    description
      "Two-phase elliptic-curve key";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       NIST SP800-56A. ALG_ID: 0x001D";
  }

  identity TPM_ALG_KDF1_SP800_56A {
    if-feature "tpm20";
    base tpm20;
    base hash;
    base method;
    description
      "Concatenation key derivation function";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       NIST SP800-56A  (approved alternative1) section 5.8.1.
       ALG_ID: 0x0020";
  }

  identity TPM_ALG_KDF2 {
    if-feature "tpm20";
    base tpm20;
    base hash;
    base method;
    description
      "Key derivation function";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       IEEE 1363a-2004 KDF2 section 13.2. ALG_ID: 0x0021";
  }

  identity TPM_ALG_KDF1_SP800_108 {
    base TPM_ALG_KDF2;
    description
      "A key derivation method";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       NIST SP800-108 - Section 5.1 KDF. ALG_ID: 0x0022";
  }

  identity TPM_ALG_ECC {
    if-feature "tpm20";
    base tpm20;
    base asymmetric;
    base object_type;
    description
      "Prime field ECC";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       ISO/IEC 15946-1. ALG_ID: 0x0023";
  }

  identity TPM_ALG_SYMCIPHER {
    if-feature "tpm20";
    base tpm20;
    base symmetric;
    base object_type;
    description
      "Object type for a symmetric block cipher";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       TCG TPM 2.0 library specification. ALG_ID: 0x0025";
  }

  identity TPM_ALG_CAMELLIA {
    if-feature "tpm20";
    base tpm20;
    base symmetric;
    description
      "The Camellia algorithm";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       ISO/IEC 18033-3. ALG_ID: 0x0026";
  }

  identity TPM_ALG_SHA3_256 {
    if-feature "tpm20";
    base tpm20;
    base hash;
    description
      "ISO/IEC 10118-3 - the SHA 256 algorithm";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       NIST PUB FIPS 202. ALG_ID: 0x0027";
  }

  identity TPM_ALG_SHA3_384 {
    if-feature "tpm20";
    base tpm20;
    base hash;
    description
      "The SHA 384 algorithm";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       NIST PUB FIPS 202. ALG_ID: 0x0028";
  }

  identity TPM_ALG_SHA3_512 {
    if-feature "tpm20";
    base tpm20;
    base hash;
    description
      "The SHA 512 algorithm";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       NIST PUB FIPS 202. ALG_ID: 0x0029";
  }

  identity TPM_ALG_CMAC {
    if-feature "tpm20";
    base tpm20;
    base symmetric;
    base signing;
    description
      "block Cipher-based Message Authentication Code (CMAC)";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       ISO/IEC 9797-1:2011 Algorithm 5. ALG_ID: 0x003F";
  }

  identity TPM_ALG_CTR {
    if-feature "tpm20";
    base tpm20;
    base symmetric;
    base encryption_mode;
    description
      "Counter mode";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       ISO/IEC 10116. ALG_ID: 0x0040";
  }

  identity TPM_ALG_OFB {
    base tpm20;
    base symmetric;
    base encryption_mode;
    description
      "Output Feedback mode";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       ISO/IEC 10116. ALG_ID: 0x0041";
  }

  identity TPM_ALG_CBC {
    if-feature "tpm20";
    base tpm20;
    base symmetric;
    base encryption_mode;
    description
      "Cipher Block Chaining mode";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       ISO/IEC 10116. ALG_ID: 0x0042";
  }

  identity TPM_ALG_CFB {
    if-feature "tpm20";
    base tpm20;
    base symmetric;
    base encryption_mode;
    description
      "Cipher Feedback mode";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       ISO/IEC 10116. ALG_ID: 0x0043";
  }

  identity TPM_ALG_ECB {
    if-feature "tpm20";
    base tpm20;
    base symmetric;
    base encryption_mode;
    description
      "Electronic Codebook mode";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       ISO/IEC 10116. ALG_ID: 0x0044";
  }

  identity TPM_ALG_CCM {
    if-feature "tpm20";
    base tpm20;
    base symmetric;
    base signing;
    base encryption_mode;
    description
      "Counter with Cipher Block Chaining-Message Authentication
       Code (CCM)";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       NIST SP800-38C. ALG_ID: 0x0050";
  }

  identity TPM_ALG_GCM {
    if-feature "tpm20";
    base tpm20;
    base symmetric;
    base signing;
    base encryption_mode;
    description
      "Galois/Counter Mode (GCM)";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       NIST SP800-38D. ALG_ID: 0x0051";
  }

  identity TPM_ALG_KW {
    if-feature "tpm20";
    base tpm20;
    base symmetric;
    base signing;
    base encryption_mode;
    description
      "AES Key Wrap (KW)";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       NIST SP800-38F. ALG_ID: 0x0052";
  }

  identity TPM_ALG_KWP {
    if-feature "tpm20";
    base tpm20;
    base symmetric;
    base signing;
    base encryption_mode;
    description
      "AES Key Wrap with Padding (KWP)";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       NIST SP800-38F. ALG_ID: 0x0053";
  }

  identity TPM_ALG_EAX {
    if-feature "tpm20";
    base tpm20;
    base symmetric;
    base signing;
    base encryption_mode;
    description
      "Authenticated-Encryption Mode";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       NIST SP800-38F. ALG_ID: 0x0054";
  }

  identity TPM_ALG_EDDSA {
    if-feature "tpm20";
    base tpm20;
    base asymmetric;
    base signing;
    description
      "Edwards-curve Digital Signature Algorithm (PureEdDSA)";
    reference
      "TCG-Algos:TCG Algorithm Registry Rev1.32  Table 3 and
       RFC 8032. ALG_ID: 0x0060";
  }
}

]]>


Note that not all cryptographic functions are required for use by ietf-tpm-remote-attestation.yang. However, the full definition of Table 3 of  will allow use by additional YANG specifications.