Mandatory-to-Implement Algorithms for Authors and Recipients of Software Update for the Internet of Things manifests
draft-ietf-suit-mti-02

SUIT                                                            B. Moran
Internet-Draft                                               Arm Limited
Intended status: Standards Track                          Ø. Rønningstad
Expires: 4 March 2024                               Nordic Semiconductor
                                                            A. Tsukamoto
                                                  ALAXALA Networks Corp.
                                                        1 September 2023

Mandatory-to-Implement Algorithms for Authors and Recipients of Software
              Update for the Internet of Things manifests
                         draft-ietf-suit-mti-02

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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 4 March 2024.

Copyright Notice

   Copyright (c) 2023 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   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 . . . . . . . . . . . . .   3
     3.2.  Current Asymmetric MTI Profile 1:
           suit-sha256-es256-ecdh-a128ctr  . . . . . . . . . . . . .   4
     3.3.  Current Asymmetric MTI Profile 2:
           suit-sha256-eddsa-ecdh-a128ctr  . . . . . . . . . . . . .   4
     3.4.  Current Asymmetric MTI Profile 3:
           suit-sha256-eddsa-ecdh-chacha-poly  . . . . . . . . . . .   4
     3.5.  Future Asymmetric MTI Profile 1:
           suit-sha256-hsslms-a256kw-a256ctr . . . . . . . . . . . .   5
   4.  Reporting Profiles  . . . . . . . . . . . . . . . . . . . . .   5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   7.  A.  Full CDDL . . . . . . . . . . . . . . . . . . . . . . . .   7
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

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

   *  Three "Current" Asymmetric MTI profiles

   *  One "Future" Asymmetric MTI profile

   At least one MTI algorithm in each category MUST be FIPS qualified.

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   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.

   Authors MUST implement all MTI profiles.  Authors MAY implement any
   number of other profiles.

   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

   *  Encryption Algorithms

3.  Profiles

   Recognized profiles are defined below.

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

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3.2.  Current 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 + HKDF-256 | -25      |
            +----------------+--------------------+----------+
            | Encryption     | A128CTR            | -65534   |
            +----------------+--------------------+----------+

                                 Table 2

3.3.  Current 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 + HKDF-256 | -25      |
            +----------------+--------------------+----------+
            | Encryption     | A128CTR            | -65534   |
            +----------------+--------------------+----------+

                                 Table 3

3.4.  Current Asymmetric MTI Profile 3: suit-sha256-eddsa-ecdh-chacha-
      poly

            +================+====================+==========+
            | Algorithm Type | Algorithm          | COSE Key |
            +================+====================+==========+
            | Digest         | SHA-256            | -16      |
            +----------------+--------------------+----------+
            | Authentication | EDDSA              | -8       |
            +----------------+--------------------+----------+
            | Key Exchange   | ECDH-ES + HKDF-256 | -25      |
            +----------------+--------------------+----------+
            | Encryption     | ChaCha20/Poly1305  | 24       |
            +----------------+--------------------+----------+

                                 Table 4

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3.5.  Future 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       |
                 +----------------+-----------+----------+
                 | Encryption     | A256CTR   | -65532   |
                 +----------------+-----------+----------+

                                  Table 5

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-ecdh-a128ctr.  In this case, the
   closest equivalent profile SHOULD be used, for example suit-sha256-
   ecdsa-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 [I-D.ietf-cose-aes-ctr-and-cbc].  All
   of the AES-CTR security considerations in
   [I-D.ietf-cose-aes-ctr-and-cbc] 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.

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   *  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)

   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  |-25     |-65534    |[-16, -7, |Section  |
   |sha256-es256-|         |      |    |        |          |-25,      |3.2      |
   |ecdh-a128ctr |         |      |    |        |          |-65534]   |         |
   +-------------+---------+------+----+--------+----------+----------+---------+
   |suit-sha256- |MANDATORY|-16   |-8  |-25     |-65534    |[-16, -8, |Section  |
   |eddsa-ecdh-  |         |      |    |        |          |-25,      |3.3      |
   |a128ctr      |         |      |    |        |          |-65534]   |         |
   +-------------+---------+------+----+--------+----------+----------+---------+
   |suit-sha256- |MANDATORY|-16   |-8  |-25     |24        |[-16, -8, |Section  |
   |eddsa-ecdh-  |         |      |    |        |          |-25, 24]  |3.4      |
   |chacha-poly  |         |      |    |        |          |          |         |
   +-------------+---------+------+----+--------+----------+----------+---------+
   |suit-sha256- |MANDATORY|-16   |-46 |-5      |-65532    |[-16, -46,|Section  |
   |hsslms-      |         |      |    |        |          |-5,       |3.5      |
   |a256kw-      |         |      |    |        |          |-65532]   |         |
   |a256ctr      |         |      |    |        |          |          |         |
   +-------------+---------+------+----+--------+----------+----------+---------+

                                  Table 6

   New entries to this registry require standards action.

   -- back

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7.  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.

   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-eddsa-ecdh-chacha-poly
   SUIT_COSE_tool_tweak /= suit-sha256-hsslms-a256kw-a256ctr

   SUIT_COSE_tool_tweak /= SUIT_COSE_Profile_HMAC_A128KW_A128CTR
   SUIT_COSE_tool_tweak /= SUIT_COSE_Profile_ES256_ECDH_A128CTR
   SUIT_COSE_tool_tweak /= SUIT_COSE_Profile_EDDSA_ECDH_A128CTR
   SUIT_COSE_tool_tweak /= SUIT_COSE_Profile_EDDSA_ECDH_CHACHA20_POLY1304
   SUIT_COSE_tool_tweak /= SUIT_COSE_Profile_HSSLMS_A256KW_A256CTR

   suit-sha256-hmac-a128kw-a128ctr = [-16, 5, -3, -65534]
   suit-sha256-es256-ecdh-a128ctr = [-16, -7, -25, -65534]
   suit-sha256-eddsa-ecdh-a128ctr = [-16, -8, -25, -65534]
   suit-sha256-eddsa-ecdh-chacha-poly = [-16, -8, -25, 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_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<authid, encid> = SUIT_COSE_Messages<authid,encid>

   SUIT_COSE_Messages<authid, encid> = SUIT_COSE_Untagged_Message<authid, encid> /
       SUIT_COSE_Tagged_Message<authid, encid>

   SUIT_COSE_Untagged_Message<authid, encid> = SUIT_COSE_Sign<authid> /
       SUIT_COSE_Sign1<authid> / SUIT_COSE_Encrypt<encid> /
       SUIT_COSE_Encrypt0<encid> / SUIT_COSE_Mac<authid> /
       SUIT_COSE_Mac0<authid>

   SUIT_COSE_Tagged_Message<authid, encid> = SUIT_COSE_Sign_Tagged<authid> /
       SUIT_COSE_Sign1_Tagged<authid> / SUIT_COSE_Encrypt_Tagged<encid> /
       SUIT_COSE_Encrypt0_Tagged<encid> / SUIT_COSE_Mac_Tagged<authid> /

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       SUIT_COSE_Mac0_Tagged<authid>

   ; 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<algid> = (
       protected : bstr .cbor SUIT_COSE_alg_map<algid>,
       unprotected : SUIT_COSE_header_map
   )
   SUIT_COSE_alg_map<algid> = {
       1 => algid,
       * int => any
   }

   SUIT_COSE_header_map = {
       * int => any
   }

   SUIT_COSE_Sign_Tagged<authid> = #6.98(SUIT_COSE_Sign<authid>)

   SUIT_COSE_Sign<authid> = [
       SUIT_COSE_Profile_Headers<authid>,
       payload : bstr / nil,
       signatures : [+ SUIT_COSE_Signature<authid>]
   ]

   SUIT_COSE_Signature<authid> =  [
       SUIT_COSE_Profile_Headers<authid>,
       signature : bstr
   ]

   SUIT_COSE_Sign1_Tagged<authid> = #6.18(SUIT_COSE_Sign1<authid>)

   SUIT_COSE_Sign1<authid> = [
       SUIT_COSE_Profile_Headers<authid>,
       payload : bstr / nil,
       signature : bstr
   ]

   SUIT_COSE_Encrypt_Tagged<encid> = #6.96(SUIT_COSE_Encrypt<encid>)

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   SUIT_COSE_Encrypt<encid> = [
       SUIT_COSE_Profile_Headers<encid>,
       ciphertext : bstr / nil,
       recipients : [+SUIT_COSE_recipient<encid>]
   ]

   SUIT_COSE_recipient<encid> = [
       SUIT_COSE_Profile_Headers<encid>,
       ciphertext : bstr / nil,
       ? recipients : [+SUIT_COSE_recipient<encid>]
   ]

   SUIT_COSE_Encrypt0_Tagged<encid> = #6.16(SUIT_COSE_Encrypt0<encid>)

   SUIT_COSE_Encrypt0<encid> = [
       SUIT_COSE_Profile_Headers<encid>,
       ciphertext : bstr / nil,
   ]

   SUIT_COSE_Mac_Tagged<authid> = #6.97(SUIT_COSE_Mac<authid>)

   SUIT_COSE_Mac<authid> = [
      SUIT_COSE_Profile_Headers<authid>,
      payload : bstr / nil,
      tag : bstr,
      recipients :[+SUIT_COSE_recipient<authid>]
   ]

   SUIT_COSE_Mac0_Tagged<authid> = #6.17(SUIT_COSE_Mac0<authid>)

   SUIT_COSE_Mac0<authid> = [
      SUIT_COSE_Profile_Headers<authid>,
      payload : bstr / nil,
      tag : bstr,
   ]

8.  References

8.1.  Normative References

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   [I-D.ietf-cose-aes-ctr-and-cbc]
              Housley, R. and H. Tschofenig, "CBOR Object Signing and
              Encryption (COSE): AES-CTR and AES-CBC", Work in Progress,
              Internet-Draft, draft-ietf-cose-aes-ctr-and-cbc-06, 25 May
              2023, <https://datatracker.ietf.org/doc/html/draft-ietf-
              cose-aes-ctr-and-cbc-06>.

   [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-14, 26 August 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-suit-
              firmware-encryption-14>.

   [RFC8152]  Schaad, J., "CBOR Object Signing and Encryption (COSE)",
              RFC 8152, DOI 10.17487/RFC8152, July 2017,
              <https://www.rfc-editor.org/rfc/rfc8152>.

   [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,
              <https://www.rfc-editor.org/rfc/rfc8778>.

   [RFC9052]  Schaad, J., "CBOR Object Signing and Encryption (COSE):
              Structures and Process", STD 96, RFC 9052,
              DOI 10.17487/RFC9052, August 2022,
              <https://www.rfc-editor.org/rfc/rfc9052>.

8.2.  Informative References

   [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-22, 27 February
              2023, <https://datatracker.ietf.org/doc/html/draft-ietf-
              suit-manifest-22>.

   [IANA-COSE]
              "CBOR Object Signing and Encryption (COSE)", 2022,
              <https://www.iana.org/assignments/cose/cose.xhtml>.

Authors' Addresses

   Brendan Moran
   Arm Limited

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   Email: brendan.moran.ietf@gmail.com

   Øyvind Rønningstad
   Nordic Semiconductor
   Email: oyvind.ronningstad@gmail.com

   Akira Tsukamoto
   ALAXALA Networks Corp.
   Email: akira.tsukamoto@alaxala.com

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