SUIT B. Moran Internet-Draft Arm Limited Intended status: Standards Track Ø. Rønningstad Expires: 24 April 2025 Nordic Semiconductor A. Tsukamoto ALAXALA Networks Corp. 21 October 2024 Mandatory-to-Implement Algorithms for Authors and Recipients of Software Update for the Internet of Things manifests draft-ietf-suit-mti-08 Abstract This document specifies algorithm profiles for SUIT manifest parsers and authors to ensure better interoperability. These profiles apply specifically to a constrained node software update use case. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 24 April 2025. Copyright Notice Copyright (c) 2024 IETF Trust and the persons identified as the document authors. All rights reserved. Moran, et al. Expires 24 April 2025 [Page 1] Internet-Draft MTI SUIT Algorithms October 2024 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. Symmetric MTI profile: suit-sha256-hmac-a128kw-a128ctr . . . . . . . . . . . . . 4 3.2. Current Constrained Asymmetric MTI Profile 1: suit-sha256-es256-ecdh-a128ctr . . . . . . . . . . . . . 4 3.3. Current Constrained Asymmetric MTI Profile 2: suit-sha256-eddsa-ecdh-a128ctr . . . . . . . . . . . . . 4 3.4. Current AEAD Asymmetric MTI Profile 1: suit-sha256-es256-ecdh-a128gcm . . . . . . . . . . . . . 5 3.5. Current AEAD Asymmetric MTI Profile 2: suit-sha256-eddsa-ecdh-chacha-poly . . . . . . . . . . . 5 3.6. Future Constrained Asymmetric MTI Profile 1: suit-sha256-hsslms-a256kw-a256ctr . . . . . . . . . . . . 5 4. Reporting Profiles . . . . . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . 6 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 7.1. Normative References . . . . . . . . . . . . . . . . . . 7 7.2. Informative References . . . . . . . . . . . . . . . . . 8 Appendix A. A. Full CDDL . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 1. Introduction Mandatory algorithms may change over time due to an evolving threat landscape. Algorithms are grouped into algorithm profiles to account for this. Profiles may be deprecated over time. SUIT will define five choices of MTI profile specifically for constrained node software update. These profiles are: * One Symmetric MTI profile * Two "Current" Constrained Asymmetric MTI profiles * Two "Current" AEAD Asymmetric MTI profiles Moran, et al. Expires 24 April 2025 [Page 2] Internet-Draft MTI SUIT Algorithms October 2024 * One "Future" Constrained Asymmetric MTI profile At least one MTI algorithm in each category MUST be FIPS qualified. Because SUIT presents an asymmetric communication profile, with powerful/complex manifest authors and constrained manifest recipients, the requirements for Recipients and Authors are different. Recipients MAY choose which MTI profile they wish to implement. It is RECOMMENDED that they implement the "Future" Asymmetric MTI profile. Recipients MAY implement any number of other profiles. Recipients MAY choose not to implement an encryption algorithm if encrypted payloads will never be used. Authors MUST implement all MTI profiles. Authors MAY implement any number of other profiles. AEAD is preferred over un-authenticated encryption. Where possible an AEAD profile SHOULD be selected. Certain constrained IoT applications require streaming decryption, which necessitates a non- AEAD ecryption algorithm. If the application is not a constrained device, the two AEAD profiles are RECOMMENDED. Other use-cases of SUIT MAY define their own MTI algorithms. 2. Algorithms The algorithms that form a part of the profiles defined in this document are grouped into: * Digest Algorithms * Authentication Algorithms * Key Exchange Algorithms (OPTIONAL) * Encryption Algorithms (OPTIONAL) 3. Profiles Recognized profiles are defined below. Moran, et al. Expires 24 April 2025 [Page 3] Internet-Draft MTI SUIT Algorithms October 2024 3.1. Symmetric MTI profile: suit-sha256-hmac-a128kw-a128ctr +================+=================+==========+ | Algorithm Type | Algorithm | COSE Key | +================+=================+==========+ | Digest | SHA-256 | -16 | +----------------+-----------------+----------+ | Authentication | HMAC-256 | 5 | +----------------+-----------------+----------+ | Key Exchange | A128KW Key Wrap | -3 | +----------------+-----------------+----------+ | Encryption | A128CTR | -65534 | +----------------+-----------------+----------+ Table 1 3.2. Current Constrained Asymmetric MTI Profile 1: suit-sha256-es256- ecdh-a128ctr +================+==================+==========+ | Algorithm Type | Algorithm | COSE Key | +================+==================+==========+ | Digest | SHA-256 | -16 | +----------------+------------------+----------+ | Authentication | ES256 | -7 | +----------------+------------------+----------+ | Key Exchange | ECDH-ES + A128KW | -29 | +----------------+------------------+----------+ | Encryption | A128CTR | -65534 | +----------------+------------------+----------+ Table 2 3.3. Current Constrained Asymmetric MTI Profile 2: suit-sha256-eddsa- ecdh-a128ctr +================+==================+==========+ | Algorithm Type | Algorithm | COSE Key | +================+==================+==========+ | Digest | SHA-256 | -16 | +----------------+------------------+----------+ | Authentication | EDDSA | -8 | +----------------+------------------+----------+ | Key Exchange | ECDH-ES + A128KW | -29 | +----------------+------------------+----------+ | Encryption | A128CTR | -65534 | +----------------+------------------+----------+ Moran, et al. Expires 24 April 2025 [Page 4] Internet-Draft MTI SUIT Algorithms October 2024 Table 3 3.4. Current AEAD Asymmetric MTI Profile 1: suit-sha256-es256-ecdh- a128gcm +================+==================+==========+ | Algorithm Type | Algorithm | COSE Key | +================+==================+==========+ | Digest | SHA-256 | -16 | +----------------+------------------+----------+ | Authentication | ES256 | -7 | +----------------+------------------+----------+ | Key Exchange | ECDH-ES + A128KW | -29 | +----------------+------------------+----------+ | Encryption | A128GCM | 1 | +----------------+------------------+----------+ Table 4 3.5. Current AEAD Asymmetric MTI Profile 2: suit-sha256-eddsa-ecdh- chacha-poly +================+===================+==========+ | Algorithm Type | Algorithm | COSE Key | +================+===================+==========+ | Digest | SHA-256 | -16 | +----------------+-------------------+----------+ | Authentication | EDDSA | -8 | +----------------+-------------------+----------+ | Key Exchange | ECDH-ES + A128KW | -29 | +----------------+-------------------+----------+ | Encryption | ChaCha20/Poly1305 | 24 | +----------------+-------------------+----------+ Table 5 3.6. Future Constrained Asymmetric MTI Profile 1: suit-sha256-hsslms- a256kw-a256ctr +================+===========+==========+ | Algorithm Type | Algorithm | COSE Key | +================+===========+==========+ | Digest | SHA-256 | -16 | +----------------+-----------+----------+ | Authentication | HSS-LMS | -46 | +----------------+-----------+----------+ | Key Exchange | A256KW | -5 | +----------------+-----------+----------+ Moran, et al. Expires 24 April 2025 [Page 5] Internet-Draft MTI SUIT Algorithms October 2024 | Encryption | A256CTR | -65532 | +----------------+-----------+----------+ Table 6 This draft does not specify a particular set of HSS-LMS parameters. Deep trees are RECOMMENDED due to key lifetimes in IoT devices. 4. Reporting Profiles When using reverse-direction communication, particularly data structures that are designed for reporting of update capabilities, status, progress, or success, the same profile as the is used on the SUIT manifest SHOULD be used. There are cases where this is not possible, such as suit-sha256-hsslms-a256kw-a256ctr. In this case, the closest equivalent profile SHOULD be used, for example suit- sha256-es256-ecdh-a128ctr. 5. Security Considerations For the avoidance of doubt, there are scenarios where payload or manifest encryption are not required. In these scenarios, the encryption element of the selected profile is simply not used. AES-CTR mode is specified, see [RFC9459]. All of the AES-CTR security considerations in [RFC9459] apply. A non-AEAD encryption mode is specified in this draft due to the following mitigating circumstances: * Streaming decryption must be supported. Therefore, there is no difference between AEAD and plaintext hash verification. * Out-of-order decryption must be supported. Therefore, we must use a stream cipher that supports random access. * There are no chosen plaintext attacks: the plaintext is authenticated prior to encryption. * Content Encryption Keys must be used to encrypt only once. See [I-D.ietf-suit-firmware-encryption]. As a result of these mitigating circumstances, AES-CTR is the most appropriate cipher for typical software/firmware delivery scenarios. 6. IANA Considerations IANA is requested to create a page for COSE Algorithm Profiles within the category for Software Update for the Internet of Things (SUIT) Moran, et al. Expires 24 April 2025 [Page 6] Internet-Draft MTI SUIT Algorithms October 2024 IANA is also requested to create a registry for COSE Alforithm Profiles within this page. The initial content of the registry is: +=============+=========+======+====+========+==========+==========+=========+ |Profile |Status |Digest|Auth|Key |Encryption|Descriptor|Reference| | | | | |Exchange| |Array | | +=============+=========+======+====+========+==========+==========+=========+ |suit-sha256- |MANDATORY|-16 |5 |-3 |-65534 |[-16, 5, |Section | |hmac-a128kw- | | | | | |-3, |3.1 | |a128ctr | | | | | |-65534] | | +-------------+---------+------+----+--------+----------+----------+---------+ |suit- |MANDATORY|-16 |-7 |-29 |-65534 |[-16, -7, |Section | |sha256-es256-| | | | | |-29, |3.2 | |ecdh-a128ctr | | | | | |-65534] | | +-------------+---------+------+----+--------+----------+----------+---------+ |suit-sha256- |MANDATORY|-16 |-8 |-29 |-65534 |[-16, -8, |Section | |eddsa-ecdh- | | | | | |-29, |3.3 | |a128ctr | | | | | |-65534] | | +-------------+---------+------+----+--------+----------+----------+---------+ |suit- |MANDATORY|-16 |-7 |-29 |1 |[-16, -7, |Section | |sha256-es256-| | | | | |-29, 1] |3.4 | |ecdh-a128gcm | | | | | | | | +-------------+---------+------+----+--------+----------+----------+---------+ |suit-sha256- |MANDATORY|-16 |-8 |-29 |24 |[-16, -8, |Section | |eddsa-ecdh- | | | | | |-29, 24] |3.5 | |chacha-poly | | | | | | | | +-------------+---------+------+----+--------+----------+----------+---------+ |suit-sha256- |MANDATORY|-16 |-46 |-5 |-65532 |[-16, -46,|Section | |hsslms- | | | | | |-5, |3.6 | |a256kw- | | | | | |-65532] | | |a256ctr | | | | | | | | +-------------+---------+------+----+--------+----------+----------+---------+ Table 7 New entries to this registry require standards action. 7. References 7.1. Normative References Moran, et al. Expires 24 April 2025 [Page 7] Internet-Draft MTI SUIT Algorithms October 2024 [I-D.ietf-suit-manifest] Moran, B., Tschofenig, H., Birkholz, H., Zandberg, K., and O. Rønningstad, "A Concise Binary Object Representation (CBOR)-based Serialization Format for the Software Updates for Internet of Things (SUIT) Manifest", Work in Progress, Internet-Draft, draft-ietf-suit-manifest-28, 21 October 2024, . [RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)", RFC 8152, DOI 10.17487/RFC8152, July 2017, . [RFC8778] Housley, R., "Use of the HSS/LMS Hash-Based Signature Algorithm with CBOR Object Signing and Encryption (COSE)", RFC 8778, DOI 10.17487/RFC8778, April 2020, . [RFC9052] Schaad, J., "CBOR Object Signing and Encryption (COSE): Structures and Process", STD 96, RFC 9052, DOI 10.17487/RFC9052, August 2022, . [RFC9459] Housley, R. and H. Tschofenig, "CBOR Object Signing and Encryption (COSE): AES-CTR and AES-CBC", RFC 9459, DOI 10.17487/RFC9459, September 2023, . 7.2. Informative References [I-D.ietf-suit-firmware-encryption] Tschofenig, H., Housley, R., Moran, B., Brown, D., and K. Takayama, "Encrypted Payloads in SUIT Manifests", Work in Progress, Internet-Draft, draft-ietf-suit-firmware- encryption-21, 21 October 2024, . [IANA-COSE] "CBOR Object Signing and Encryption (COSE)", 2022, . Appendix A. A. Full CDDL The following CDDL creates a subset of COSE for use with SUIT. Both tagged and untagged messages are defined. SUIT only uses tagged COSE messages, but untagged messages are also defined for use in protocols that share a ciphersuite with SUIT. Moran, et al. Expires 24 April 2025 [Page 8] Internet-Draft MTI SUIT Algorithms October 2024 To be valid, the following CDDL MUST have the COSE CDDL appended to it. The COSE CDDL can be obtained by following the directions in [RFC9052], Section 1.4. SUIT_COSE_tool_tweak /= suit-sha256-hmac-a128kw-a128ctr SUIT_COSE_tool_tweak /= suit-sha256-es256-ecdh-a128ctr SUIT_COSE_tool_tweak /= suit-sha256-eddsa-ecdh-a128ctr SUIT_COSE_tool_tweak /= suit-sha256-es256-ecdh-a128gcm SUIT_COSE_tool_tweak /= suit-sha256-eddsa-ecdh-chacha-poly SUIT_COSE_tool_tweak /= suit-sha256-hsslms-a256kw-a256ctr SUIT_COSE_tool_tweak /= SUIT_COSE_Profiles SUIT_COSE_Profiles /= SUIT_COSE_Profile_HMAC_A128KW_A128CTR SUIT_COSE_Profiles /= SUIT_COSE_Profile_ES256_ECDH_A128CTR SUIT_COSE_Profiles /= SUIT_COSE_Profile_EDDSA_ECDH_A128CTR SUIT_COSE_Profiles /= SUIT_COSE_Profile_ES256_ECDH_A128GCM SUIT_COSE_Profiles /= SUIT_COSE_Profile_EDDSA_ECDH_CHACHA20_POLY1304 SUIT_COSE_Profiles /= SUIT_COSE_Profile_HSSLMS_A256KW_A256CTR suit-sha256-hmac-a128kw-a128ctr = [-16, 5, -3, -65534] suit-sha256-es256-ecdh-a128ctr = [-16, -7, -29, -65534] suit-sha256-eddsa-ecdh-a128ctr = [-16, -8, -29, -65534] suit-sha256-es256-ecdh-a128gcm = [-16, -7, -29, 1] suit-sha256-eddsa-ecdh-chacha-poly = [-16, -8, -29, 24] suit-sha256-hsslms-a256kw-a256ctr = [-16, -46, -5, -65532] SUIT_COSE_Profile_HMAC_A128KW_A128CTR = SUIT_COSE_Profile<5, -65534> .and COSE_Messages SUIT_COSE_Profile_ES256_ECDH_A128CTR = SUIT_COSE_Profile<-7,-65534> .and COSE_Messages SUIT_COSE_Profile_EDDSA_ECDH_A128CTR = SUIT_COSE_Profile<-8,-65534> .and COSE_Messages SUIT_COSE_Profile_ES256_ECDH_A128GCM = SUIT_COSE_Profile<-7,1> .and COSE_Messages SUIT_COSE_Profile_EDDSA_ECDH_CHACHA20_POLY1304 = SUIT_COSE_Profile<-8,24> .and COSE_Messages SUIT_COSE_Profile_HSSLMS_A256KW_A256CTR = SUIT_COSE_Profile<-46,-65532> .and COSE_Messages SUIT_COSE_Profile = SUIT_COSE_Messages SUIT_COSE_Messages = SUIT_COSE_Untagged_Message / SUIT_COSE_Tagged_Message SUIT_COSE_Untagged_Message = SUIT_COSE_Sign / SUIT_COSE_Sign1 / SUIT_COSE_Encrypt / SUIT_COSE_Encrypt0 / SUIT_COSE_Mac / SUIT_COSE_Mac0 SUIT_COSE_Tagged_Message = SUIT_COSE_Sign_Tagged / SUIT_COSE_Sign1_Tagged / SUIT_COSE_Encrypt_Tagged / SUIT_COSE_Encrypt0_Tagged / SUIT_COSE_Mac_Tagged / SUIT_COSE_Mac0_Tagged Moran, et al. Expires 24 April 2025 [Page 9] Internet-Draft MTI SUIT Algorithms October 2024 ; Note: This is not the same definition as is used in COSE. ; It restricts a COSE header definition further without ; repeating the COSE definition. It should be merged ; with COSE by using the CDDL .and operator. SUIT_COSE_Profile_Headers = ( protected : bstr .cbor SUIT_COSE_alg_map, unprotected : SUIT_COSE_header_map ) SUIT_COSE_alg_map = { 1 => algid, * int => any } SUIT_COSE_header_map = { * int => any } SUIT_COSE_Sign_Tagged = #6.98(SUIT_COSE_Sign) SUIT_COSE_Sign = [ SUIT_COSE_Profile_Headers, payload : bstr / nil, signatures : [+ SUIT_COSE_Signature] ] SUIT_COSE_Signature = [ SUIT_COSE_Profile_Headers, signature : bstr ] SUIT_COSE_Sign1_Tagged = #6.18(SUIT_COSE_Sign1) SUIT_COSE_Sign1 = [ SUIT_COSE_Profile_Headers, payload : bstr / nil, signature : bstr ] SUIT_COSE_Encrypt_Tagged = #6.96(SUIT_COSE_Encrypt) SUIT_COSE_Encrypt = [ SUIT_COSE_Profile_Headers, Moran, et al. Expires 24 April 2025 [Page 10] Internet-Draft MTI SUIT Algorithms October 2024 ciphertext : bstr / nil, recipients : [+SUIT_COSE_recipient] ] SUIT_COSE_recipient = [ SUIT_COSE_Profile_Headers, ciphertext : bstr / nil, ? recipients : [+SUIT_COSE_recipient] ] SUIT_COSE_Encrypt0_Tagged = #6.16(SUIT_COSE_Encrypt0) SUIT_COSE_Encrypt0 = [ SUIT_COSE_Profile_Headers, ciphertext : bstr / nil, ] SUIT_COSE_Mac_Tagged = #6.97(SUIT_COSE_Mac) SUIT_COSE_Mac = [ SUIT_COSE_Profile_Headers, payload : bstr / nil, tag : bstr, recipients :[+SUIT_COSE_recipient] ] SUIT_COSE_Mac0_Tagged = #6.17(SUIT_COSE_Mac0) SUIT_COSE_Mac0 = [ SUIT_COSE_Profile_Headers, payload : bstr / nil, tag : bstr, ] Authors' Addresses Brendan Moran Arm Limited Email: brendan.moran.ietf@gmail.com Moran, et al. Expires 24 April 2025 [Page 11] Internet-Draft MTI SUIT Algorithms October 2024 Øyvind Rønningstad Nordic Semiconductor Email: oyvind.ronningstad@gmail.com Akira Tsukamoto ALAXALA Networks Corp. Email: akira.tsukamoto@alaxala.com Moran, et al. Expires 24 April 2025 [Page 12]