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

One or more TPMs MUST be embedded in the composite device that is providing attestation evidence via the YANG module defined in this document. The ietf-basic-remote-attestation YANG module enables a composite device to take on the role of Claimant and 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. The functions of this YANG module are restricted to 0-1 TPMs per hardware component.

This YANG module imports modules from , , , ietf-tcg-algs.yang.

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

<tpm12-challenge-response-attestation> - Allows a Verifier to request a quote of PCRs from a TPM1.2 compliant cryptoprocessor. When one or more <certificate-name> is not provided, all TPM1.2 compliant cryptoprocessors will respond. <tpm20-challenge-response-attestation> - Allows a Verifier to request a quote of PCRs from a TPM2.0 compliant cryptoprocessor. When one or more <certificate-name> is not provided, all TPM2.0 compliant cryptoprocessors will respond. <log-retrieval> - Allows a Verifier to acquire the evidence which was extended into specific PCRs.

container <rats-support-structures> - This exists when there are more than one TPM for a particular Attester. This allows each specific TPM to identify on which <compute-node> it belongs. 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 is the certificates which are associated with that TPM. As a certificate is associated with a single Attestation key, knowledge of the certificate allows a specific TPM to be identified. container <attester-supported-algos> - Identifies which TCG algorithms are available for use the Attesting platform. This allows an operator to limit algorithms available for use by RPCs to just a desired set from the universe of all allowed by TCG.

file ietf-tpm-remote-attestation@2020-09-18.yang module ietf-tpm-remote-attestation { namespace "urn:ietf:params:xml:ns:yang:ietf-tpm-remote-attestation"; prefix "tpm"; import ietf-yang-types { prefix yang; } import ietf-hardware { prefix ietfhw; } 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) 2020 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 Simplified 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). 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 Simplified 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 "2020-09-18" { description "Initial version"; reference "draft-ietf-rats-yang-tpm-charra"; } /*****************/ /* Typedefs */ /*****************/ typedef pcr { type uint8 { range "0..31"; } description "Valid index number for a PCR. At this point 0-31 is viable."; } typedef compute-node-ref { type leafref { path "/tpm:rats-support-structures/tpm:compute-nodes" + "/tpm:compute-node/tpm:node-name"; } description "This type is used to reference a hardware node. It is quite possible this leafref will eventually point to another YANG module's node."; } typedef certificate-name-ref { type leafref { path "/tpm:rats-support-structures/tpm:tpms/tpm:tpm" + "/tpm:certificates/tpm:certificate/tpm:certificate-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 and 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-asymmetric-signing-algo { description "The signature scheme that is used to sign the TPM2 Quote information response."; leaf TPM20-asymmetric-signing-algo { must "/tpm:rats-support-structures/tpm:attester-supported-algos" + "/tpm:tpm20-asymmetric-signing" { error-message "Not a platform supported " + "TPM20-asymmetric-signing-algo"; } type identityref { base taa:asymmetric; } description "The signature scheme that is used to sign the TPM2.0 Quote information response. This must be one of those supported by a platform."; default taa:TPM_ALG_RSA; } } grouping TPM12-asymmetric-signing-algo { description "The signature scheme that is used to sign the TPM12 Quote information response."; leaf TPM12-asymmetric-signing-algo { must "/tpm:rats-support-structures/tpm:attester-supported-algos" + "/tpm:tpm12-asymmetric-signing" { error-message "Not a platform supported " + "TPM12-asymmetric-signing-algo"; } type identityref { base taa:asymmetric; } description "The signature scheme that is used to sign the TPM1.2 Quote information response. This must be one of those supported by a platform."; default taa:TPM_ALG_RSA; } } 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 { must "/tpm:rats-support-structures/tpm:attester-supported-algos" + "/tpm:tpm20-hash" { error-message "Not a platform supported TPM20-hash-algo"; } type identityref { base taa:hash; } description "The hash scheme that is used to hash a TPM1.2 PCR. This must be one of those supported by a platform."; default taa:TPM_ALG_SHA256; } } grouping TPM12-hash-algo { description "The cryptographic algorithm used to hash the TPM1.2 PCRs."; leaf TPM12-hash-algo { must "/tpm:rats-support-structures/tpm:attester-supported-algos" + "/tpm:tpm12-hash" { error-message "Not a platform supported TPM12-hash-algo"; } type identityref { base taa:hash; } description "The hash scheme that is used to hash a TPM1.2 PCR. This must be one of those supported by a platform. This assumes that an algorithm other than SHA1 can be supported on some TPM1.2 cryptoprocessor variant."; default taa:TPM_ALG_SHA1; } } grouping nonce { description "A nonce to show freshness and to allow the detection of replay attacks."; leaf nonce-value { type binary; mandatory true; description "This nonce SHOULD be generated via a registered cryptographic-strength algorithm. In consequence, the length of the nonce depends on the hash algorithm used. The algorithm used in this case is independent from the hash algorithm used to create the hash-value in the response of the attestor."; } } 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. Requesting a PCR value that is not in scope of the AC used, detailed exposure via error msg should be avoided."; leaf-list pcr-index { /* the following XPATH must be updated to ensure that only selectable PCRs are allowed in the RPC must "/tpm:rats-support-structures/tpm:tpms" + "/tpm:tpm[tpm-name = current()]" + "/tpm:tpm[TPM12-pcrs = current()]" { error-message "Acquiring this PCR index is not supported"; } */ type pcr; description "The numbers/indexes of the PCRs. At the moment this is limited to 32."; } } 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 "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 { /* the following XPATH must be updated to ensure that only selectable PCRs are allowed in the RPC must "/tpm:rats-support-structures/tpm:tpms" + "/tpm:tpm[tpm-name = current()]" + "/tpm:tpm20-pcr-bank[pcr-index = current()]" { error-message "Acquiring this PCR index is not supported"; } */ type tpm:pcr; description "The numbers of the PCRs that which are being tracked with a hash based on the TPM20-hash-algo."; } } } grouping certificate-name-ref { description "Identifies a certificate in a keystore."; leaf certificate-name { type certificate-name-ref; description "Identifies a certificate in a keystore."; } } grouping tpm-name { description "A unique TPM on a device."; leaf tpm-name { type string; description "Unique system generated name for a TPM on a device."; } } grouping tpm-name-selector { description "One or more TPM on a device."; leaf-list tpm-name { type string; config false; 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."; } } grouping compute-node-identifier { description "In a distributed system with multiple compute nodes this is the node identified by name and physical-index."; leaf node-id { type string; description "ID of the compute node, such as Board Serial Number."; } leaf node-physical-index { if-feature ietfhw:entity-mib; type int32 { range "1..2147483647"; } config false; description "The entPhysicalIndex for the compute node."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalIndex"; } } grouping tpm12-pcr-info-short { description "This structure is for defining a digest at release when the only information that is necessary is the release configuration."; uses tpm12-pcr-selection; leaf locality-at-release { type uint8; description "This SHALL be the locality modifier required to release the information (TPM 1.2 type TPM_LOCALITY_SELECTION)"; reference "TPM Main Part 2 TPM Structures v1.2 July 2007 Section 8.6"; } leaf digest-at-release { type binary; description "This SHALL be the digest of the PCR indices and PCR values to verify when revealing auth data (TPM 1.2 type TPM_COMPOSITE_HASH)."; reference "TPM Main Part 2 TPM Structures v1.2 July 2007 Section 5.4.1."; } } grouping tpm12-version { description "This structure provides information relative the version of the TPM."; list version { description "This indicates the version of the structure (TPM 1.2 type TPM_STRUCT_VER). This MUST be 1.1.0.0."; reference "TPM Main Part 2 TPM Structures v1.2 July 2007 Section 5.1."; leaf major { type uint8; description "Indicates the major version of the structure. MUST be 0x01."; } leaf minor { type uint8; description "Indicates the minor version of the structure. MUST be 0x01."; } leaf rev-Major { type uint8; description "Indicates the rev major version of the structure. MUST be 0x00."; } leaf rev-Minor { type uint8; description "Indicates the rev minor version of the structure. MUST be 0x00."; } } } grouping tpm12-quote-info-common { description "These statements are within both quote variants of the TPM 1.2"; reference "TPM Main Part 2 TPM Structures v1.2 July 2007, Section 11.3 & 11.4."; leaf fixed { type binary; description "This SHALL always be the string 'QUOT' or 'QUO2' (length is 4 bytes)."; } leaf external-data { type binary; description "160 bits of externally supplied data, typically a nonce."; } leaf signature-size { type uint32; description "The size of TPM 1.2 'signature' value."; } leaf signature { type binary; description "Signature over hash of tpm12-quote-info2'."; } } grouping tpm12-quote-info { description "This structure provides the mechanism for the TPM to quote the current values of a list of PCRs (as used by the TPM_Quote2 command)."; uses tpm12-version; leaf digest-value { type binary; description "This SHALL be the result of the composite hash algorithm using the current values of the requested PCR indices (TPM 1.2 type TPM_COMPOSITE_HASH.)"; } } grouping tpm12-quote-info2 { description "This structure provides the mechanism for the TPM to quote the current values of a list of PCRs (as used by the TPM_Quote2 command)."; leaf tag { type uint8; description "This SHALL be TPM_TAG_QUOTE_INFO2."; } uses tpm12-pcr-info-short; } grouping tpm12-cap-version-info { description "TPM returns the current version and revision of the TPM 1.2 ."; list TPM_PCR_COMPOSITE { description "The TPM 1.2 TPM_PCRVALUEs for the pcr-indices."; reference "TPM Main Part 2 TPM Structures v1.2 July 2007, Section 8.2"; uses tpm12-pcr-selection; leaf value-size { type uint32; description "This SHALL be the size of the 'tpm12-pcr-value' field (not the number of PCRs)."; } leaf-list tpm12-pcr-value { type binary; description "The list of TPM_PCRVALUEs from each PCR selected in sequence of tpm12-pcr-selection."; } list version-info { description "An optional output parameter from a TPM 1.2 TPM_Quote2."; leaf tag { type uint16; /* This should be converted into an ENUM */ description "The TPM 1.2 version and revision (TPM 1.2 type TPM_STRUCTURE_TAG). This MUST be TPM_CAP_VERSION_INFO (0x0030)"; } uses tpm12-version; leaf spec-level { type uint16; description "A number indicating the level of ordinals supported."; } leaf errata-rev { type uint8; description "A number indicating the errata version of the specification."; } leaf tpm-vendor-id { type binary; description "The vendor ID unique to each TPM manufacturer."; } leaf vendor-specific-size { type uint16; description "The size of the vendor-specific area."; } leaf vendor-specific { type binary; description "Vendor specific information."; } } } } grouping tpm12-pcr-composite { description "The actual values of the selected PCRs (a list of TPM_PCRVALUEs (binary) and associated metadata for TPM 1.2."; list TPM_PCR_COMPOSITE { description "The TPM 1.2 TPM_PCRVALUEs for the pcr-indices."; reference "TPM Main Part 2 TPM Structures v1.2 July 2007, Section 8.2"; uses tpm12-pcr-selection; leaf value-size { type uint32; description "This SHALL be the size of the 'tpm12-pcr-value' field (not the number of PCRs)."; } leaf-list tpm12-pcr-value { type binary; description "The list of TPM_PCRVALUEs from each PCR selected in sequence of tpm12-pcr-selection."; } } } 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; uses compute-node-identifier; uses tpm12-quote-info-common; choice tpm12-quote { mandatory true; description "Either a tpm12-quote-info or tpm12-quote-info2, depending on whether TPM_Quote or TPM_Quote2 was used (cf. input field add-verson)."; case tpm12-quote1 { description "BIOS/UEFI event logs"; uses tpm12-quote-info; uses tpm12-pcr-composite; } case tpm12-quote2 { description "BIOS/UEFI event logs"; uses tpm12-quote-info2; } } } grouping tpm20-attestation { description "Contains an instance of TPM2 style signed cryptoprocessor measurements. It is supplemented by unsigned Attester information."; leaf TPMS_QUOTE_INFO { mandatory true; type binary; description "A hash of the latest PCR values (and the hash algorithm used) which have been returned from a Verifier for the selected PCRs and Hash Algorithms."; reference "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."; } uses node-uptime; uses compute-node-identifier; list unsigned-pcr-values { description "PCR values in each PCR bank. This often should not be necessary for TPM2, as the raw information needing signature and hash validation will be coming from the 'quote' leaf"; 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."; } } } } 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 an event log corresponding to the event that extended the PCR"; leaf event-number { type uint32; description "Unique event number of this event"; } leaf event-type { type uint32; description "log event type"; } 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"; } } leaf event-size { type uint32; description "Size of the event data"; } leaf-list event-data { type uint8; description "The event data size determined by event-size"; } } 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 an hash log extend event for IMA measurements"; leaf event-number { type uint64; description "Unique number for this event for sequencing"; } 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 that was measured"; } leaf filedata-hash { type binary; description "Hash of filedata"; } 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 "The file signature"; } } 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 netequip-boot-event { description "Defines an hash log extend event for Network Equipment Boot."; leaf event-number { type uint64; description "Unique number for this event for sequencing"; } leaf filename-hint { type string; description "File that was measured"; } leaf filedata-hash { type binary; description "Hash of filedata"; } leaf filedata-hash-algorithm { type string; description "Algorithm used for filedata-hash."; } leaf file-version { type string; description "File version information."; } leaf file-type { type string; description "Indicating at which boot stage the file is loaded, such as BIOS, BootLoader, etc."; } leaf pcr-index { type pcr; description "Defines the PCR index that this event extended"; } } grouping network-equipment-boot-event-log { description "Measurement log created by Network Equipment Boot."; list boot-event-entry { key event-number; description "Ordered list of Network Equipment Boot event logs by event-number."; uses netequip-boot-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 { description "BIOS/UEFI event logs"; container bios-event-logs { description "BIOS/UEFI event logs"; uses bios-event-log; } } case ima { description "IMA event logs."; container ima-event-logs { description "IMA event logs."; uses ima-event-log; } } case 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 add-version { type boolean; description "Whether or not to include TPM_CAP_VERSION_INFO; if true, then TPM_Quote2 must be used to create the response."; reference "TPM Main Part 2 TPM Structures v1.2 July 2007, Section 21.6"; } leaf-list certificate-name { must "/tpm:rats-support-structures/tpm:tpms" + "/tpm:tpm[tpm:tpm-firmware-version='taa:tpm12']" + "/tpm:certificates/" + "/tpm:certificate[certificate-name-ref=current()]" { error-message "Not an available TPM1.2 AIK certificate."; } type certificate-name-ref; 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 to refer to dedicated TPM in composite devices, e.g. smart NICs, is still a TODO."; 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 { must "/tpm:rats-support-structures/tpm:tpms" + "/tpm:tpm[tpm:tpm-firmware-version='taa:tpm20']" + "/tpm:certificates/" + "/tpm:certificate[certificate-name-ref=current()]" { error-message "Not an available TPM2.0 AIK certificate."; } type certificate-name-ref; 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 TPM2b_Quote in one TPM chip 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 { list log-selector { description "Selection of log entries to be reported."; uses tpm-name-selector; 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 an log event which matches 1:1 with a unique event record contained within the log. Log entries subsequent to 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 subsequent to 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 subsequent to 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."; } } uses log-identifier; } output { container system-event-logs { description "The requested data of the measurement event logs"; list node-data { unique "tpm-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 { presence "Indicates that more than one TPM exists on a device."; description "Holds the set device subsystems/components in this composite device that support TPM operations."; list compute-node { key node-id; config false; min-elements 2; uses compute-node-identifier; description "A components in this composite device that RATS which supports TPM operations."; 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 tpm-name; unique "tpm-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; description "Answers the question: is this TPM is a hardware based TPM?"; } leaf tpm-physical-index { if-feature ietfhw:entity-mib; type int32 { range "1..2147483647"; } config false; description "The entPhysicalIndex for the TPM."; reference "RFC 6933: Entity MIB (Version 4) - entPhysicalIndex"; } leaf tpm-path { type string; config false; description "Path to a unique TPM on a device. This can change agross reboots."; } leaf compute-node { when "../../../compute-nodes"; type compute-node-ref; config false; mandatory true; description "When there is more that one TPM, this indicates for which compute node this TPM services."; } leaf tpm-manufacturer { type string; config false; description "TPM manufacturer name."; } leaf tpm-firmware-version { type identityref { base taa:cryptoprocessor; } mandatory true; description "Identifies the cryptoprocessor API set supported. This cannot be configured. However it is referenced via XPATH as part of configuration, so is shown as 'rw' to eliminate YANG warnings related NMDA."; } uses TPM12-hash-algo { when "tpm-firmware-version = '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 "../tpm-firmware-version = 'taa:tpm12'"; type pcr; description "The PCRs which may be extracted from this TPM1.2 compliant cryptoprocessor."; } list tpm20-pcr-bank { when "../tpm-firmware-version = '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 "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 { must "/tpm:rats-support-structures" + "/tpm:attester-supported-algos" + "/tpm:tpm20-hash" { error-message "Not a platform supported TPM20-hash-algo"; } type identityref { base taa:hash; } 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 tpm-status { type enumeration { enum operational { value 0; description "The TPM currently is currently running normally and is ready to accept and process TPM quotes."; reference "TPM-Rev-2.0-Part-1-Architecture-01.07-2014-03-13.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 AK certificates."; list certificate { key "certificate-name"; description "Three types of certificates can be accessed via this statement, including Initial Attestation Key Cert, Local Attestation Key Cert or Endorsement Key Cert."; leaf certificate-name { type string; description "An arbitrary name uniquely identifying a certificate associated within key within a TPM."; } leaf certificate-keystore-ref { type leafref { path "/ks:keystore/ks:asymmetric-keys/ks:asymmetric-key" + "/ks:certificates/ks:certificate/ks:name"; } description "A reference to a specific certificate of an asymmetric key in the Keystore."; /* Note: It is also possible to import a grouping which allows local definition via an imported keystore schema. */ } leaf certificate-type { type enumeration { enum endorsement-cert { value 0; description "Endorsement Key (EK) Certificate type."; } enum initial-attestation-cert { value 1; description "Initial Attestation key (IAK) Certificate type."; } enum local-attestation-cert { value 2; description "Local Attestation Key (LAK) Certificate type."; } } description "Type of this certificate"; } } } } } container attester-supported-algos { description "Identifies which TPM algorithms are available for use on an attesting platform."; leaf-list tpm12-asymmetric-signing { if-feature "taa:TPM12"; when "../../tpm:tpms" + "/tpm:tpm[tpm:tpm-firmware-version='taa:tpm12']"; type identityref { base taa:asymmetric; } description "Platform Supported TPM12 asymmetric algorithms."; } leaf-list tpm12-hash { if-feature "taa:TPM12"; when "../../tpm:tpms" + "/tpm:tpm[tpm:tpm-firmware-version='taa:tpm12']"; type identityref { base taa:hash; } description "Platform supported TPM12 hash algorithms."; } leaf-list tpm20-asymmetric-signing { if-feature "taa:TPM20"; when "../../tpm:tpms" + "/tpm:tpm[tpm:tpm-firmware-version='taa:tpm20']"; type identityref { base taa:asymmetric; } description "Platform Supported TPM20 asymmetric algorithms."; } leaf-list tpm20-hash { if-feature "taa:TPM20"; when "../../tpm:tpms" + "/tpm:tpm[tpm:tpm-firmware-version='taa:tpm20']"; type identityref { base taa:hash; } description "Platform supported TPM20 hash algorithms."; } } } }

]]>




Cryptographic algorithm types were initially included within -v14 NETCONF’s iana-crypto-types.yang.  Unfortunately all this content including the algorithms needed here failed to make the -v15 used WGLC.   As a result 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.



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 API is present on an Attester.  Most commonly, only one type of cryptoprocessor will be available on an Attester.




There are three types of identities in this model.

The first are the cryptographic functions supportable 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 .

The second are API specifications for tpms: <tpm12> and <tpm2>.

The third are 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 .



 ietf-tcg-algs@2020-09-18.yang
module ietf-tcg-algs {
  yang-version 1.1;
  namespace "urn:ietf:params:xml:ns:yang:ietf-tcg-algs";
  prefix taa;

  organization
    "IETF RATS Working Group";

  contact
    "WG Web:   
     WG List:  
     Author:   Eric Voit ";

  description
    "This module defines a identities for asymmetric algorithms.
    
     Copyright (c) 2020 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 Simplified
     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 2020-09-18 {
    description
      "Initial version";
    reference
      "RFC XXXX: tbd";
  }

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

  feature TPM12 {
    description
      "This feature indicates algorithm support for the TPM 1.2 API
      as per TPM-main-1.2-Rev94-part-2, Section 4.8.";
  }

  feature TPM20 {
    description
      "This feature indicates algorithm support for the TPM 2.0 API 
      as per TPM-Rev-2.0-Part-1-Architecture-01.38 Section 11.4.";
  }


  /*****************/
  /*  Identities   */
  /*****************/
  
  /*  There needs to be collasping/verification of some of the identity  
      types between the various algorithm types listed below */

  identity asymmetric {
    description
      "A TCG recognized asymmetric algorithm with a public and 
      private key.";
    reference
      "http://trustedcomputinggroup.org/resource/tcg-algorithm-registry/
      TCG_Algorithm_Registry_r1p32_pub Table 2";
  }

  identity symmetric {
    description
      "A TCG recognized symmetric algorithm with only a private key.";
    reference
      "TCG_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub Table 2";
  }

  identity signing {
    description
      "A TCG recognized signing algorithm";
    reference
      "TCG_Algorithm_Registry_r1p32_pub Table 2";
  }

  identity anonymous_signing {
    description
      "A TCG recognized anonymous signing algorithm.";
    reference
      "TCG_Algorithm_Registry_r1p32_pub Table 2";
  }

  identity encryption_mode {
    description
      "A TCG recognized encryption mode.";
    reference
      "TCG_Algorithm_Registry_r1p32_pub Table 2";
  }  

  identity method {
    description
      "A TCG recognized method such as a mask generation function.";
    reference
      "TCG_Algorithm_Registry_r1p32_pub Table 2";
  }
  
  identity object_type {
    description
      "A TCG recognized object type.";
    reference
      "TCG_Algorithm_Registry_r1p32_pub Table 2";
  }

  identity cryptoprocessor {
    description
      "Base identity identifying a crytoprocessor.";
  }
  
  identity tpm12 {
    if-feature "TPM12";
    base cryptoprocessor;
    description
      "Supportable by a TPM1.2.";
    reference
      "TPM-Main-Part-2-TPM-Structures_v1.2_rev116_01032011.pdf
      TPM_ALGORITHM_ID values, page 18";
  }
  
  identity tpm20 {
    if-feature "TPM12";
    base cryptoprocessor;
    description
      "Supportable by a TPM2.";
    reference  
      "TPM-Rev-2.0-Part-2-Structures-01.38.pdf
      The TCG Algorithm Registry. Table 9";
  } 
  
  identity TPM_ALG_RSA {
    if-feature "TPM12 or TPM20";
    base tpm12;  
    base tpm20;
    base asymmetric;
    base object_type;
    description
      "RSA algorithm";
    reference  
      "TCG_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub Table 3, 
      ISO/IEC 9797-2 and RFC2014. ALG_ID: 0x0005";    

  }
      
  identity TPM_ALG_AES  {
    if-feature "TPM12";
    base tpm12;
    base symmetric;
    description
      "The AES algorithm with various key sizes";
    reference  
      "TCG_Algorithm_Registry_r1p32_pub Table 3 and
      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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub Table 3 and
      TCG TPM 2.0 library specification. . 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_Algorithm_Registry_r1p32_pub Table 3 and
      TCG TPM 2.0 library specification. ALG_ID: 0x000A";

  }

  identity TPM_ALG_SHA256 {
    if-feature "TPM20";
    base tpm20;
    base hash;
    description
      "The SHA 256 algorithm";
    reference  
      "TCG_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub Table 3 and
      ISO/IEC 10118-3. ALG_ID: 0x000D";    

  }

  identity TPM_ALG_NULL {
    if-feature "TPM20";
    base tpm20;
    description
      "NULL algorithm";
    reference  
      "TCG_Algorithm_Registry_r1p32_pub Table 3 and
      TCG TPM 2.0 library specification. ALG_ID: 0x0010";     

  }

  identity TPM_ALG_SM3_256 {
    if-feature "TPM20";
    base tpm20;
    base hash;
    description
      "The SM3 hash algorithm.";
    reference  
      "TCG_Algorithm_Registry_r1p32_pub Table 3 and
      GM/T 0004-2012 - SM3_256. ALG_ID: 0x0012";    

  }

  identity TPM_ALG_SM4 {
    if-feature "TPM20";
    base tpm20;
    base symmetric;
    description
      "SM4 symmetric block cipher";
    reference  
      "TCG_Algorithm_Registry_r1p32_pub Table 3 and
      GB/T 32907-2016. ALG_ID: 0x0013";    

  }

  identity TPM_ALG_RSASSA {
    if-feature "TPM20";
    base tpm20;
    base asymmetric;
    base signing;  
    description
      "Signature algorithm defined in section 8.2 (RSASSAPKCS1-v1_5)";
    reference  
      "TCG_Algorithm_Registry_r1p32_pub Table 3 and RFC 8017.
      ALG_ID: 0x0014";    

  }

  identity TPM_ALG_RSAES {
    if-feature "TPM20";
    base tpm20;
    base asymmetric;
    base encryption_mode;
    description
      "Signature algorithm defined in section 7.2 (RSAES-PKCS1-v1_5)";
    reference  
      "TCG_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub Table 3 and
      NIST SP800-56A and RFC 7748. 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub Table 3 and
      A GM/T 0003.1–2012, GM/T 0003.2–2012, GM/T 0003.3–2012,
      GM/T 0003.5–2012 SM2. ALG_ID: 0x001B";    

  }

  identity TPM_ALG_ECSCHNORR {
    if-feature "TPM20";
    base tpm20;
    base asymmetric;
    base signing;
    description
      "Elliptic-curve based Schnorr signature";
    reference  
      "TCG_Algorithm_Registry_r1p32_pub Table 3 and
      TCG TPM 2.0 library specification. ALG_ID: 0x001C";       

  }

  identity TPM_ALG_ECMQV {
    if-feature "TPM20";
    base tpm20;
    base asymmetric;
    base method;
    description
      "Two-phase elliptic-curve key";
    reference  
      "TCG_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub Table 3 and
      ISO/IEC 15946-1. ALG_ID: 0x0023";    

  }

  identity TPM_ALG_SYMCIPHER {
    if-feature "TPM20";
    base tpm20;
    description
      "Object type for a symmetric block cipher";
    reference  
      "TCG_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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_Algorithm_Registry_r1p32_pub 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.