



RATS Working Group                                          M. U. Sardar
Internet-Draft                                                TU Dresden
Updates: 9334 (if approved)                              20 October 2025
Intended status: Informational                                          
Expires: 23 April 2026


             Guidelines for Security Considerations of RATS
                     draft-rats-sardar-sec-cons-00

Abstract

   This document aims to provide guidelines and best practices for
   writing security considerations for technical specifications for RATS
   targeting the needs of implementers, researchers, and protocol
   designers.

About This Document

   This note is to be removed before publishing as an RFC.

   The latest revision of this draft can be found at https://muhammad-
   usama-sardar.github.io/rats-sec-cons/draft-rats-sardar-sec-cons.html.
   Status information for this document may be found at
   https://datatracker.ietf.org/doc/draft-rats-sardar-sec-cons/.

   Source for this draft and an issue tracker can be found at
   https://github.com/muhammad-usama-sardar/rats-sec-cons.

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
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   This Internet-Draft will expire on 23 April 2026.






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Copyright Notice

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   2
   3.  General Hierarchy of Authentication . . . . . . . . . . . . .   3
   4.  Attacks . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Examples of Specifications That Could Be Improved . . . . . .   3
     5.1.  RFC9334 . . . . . . . . . . . . . . . . . . . . . . . . .   3
       5.1.1.  Unprotected Evidence  . . . . . . . . . . . . . . . .   3
       5.1.2.  Missing Roles and Conceptual Messages . . . . . . . .   4
   6.  Examples of Specifications That Are Detrimental for
           Security  . . . . . . . . . . . . . . . . . . . . . . . .   4
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   While [I-D.irtf-cfrg-cryptography-specification] provides excellent
   guidelines, remote attestation [RFC9334] has several distinguishing
   features which necessitate a separate document.  One specific example
   of such feature is architectural complexity.

2.  Conventions and Definitions

   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 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.



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3.  General Hierarchy of Authentication

   [Gen-Approach] proposes general hierarchy of one-way authentication,
   which can help precisely state the intended level of authentication
   (in decreasing order):

   *  One-way injective agreement

   *  One-way non-injective agreement

   *  Aliveness

   Recentness can be added to each of these levels of authentication.

4.  Attacks

   Security considerations in RATS specifications need to clarify how
   the following attacks are avoided or mitigated:

   *  Diversion attacks [Meeting-122-TLS-Slides]

   *  Relay attacks

   *  Replay attacks

5.  Examples of Specifications That Could Be Improved

5.1.  RFC9334

5.1.1.  Unprotected Evidence

   Section 7.4 of [RFC9334] has:

   |  A conveyance protocol that provides authentication and integrity
   |  protection can be used to convey Evidence that is otherwise
   |  unprotected (e.g., not signed).

   Using a conveyance protocol that provides authentication and
   integrity protection, such as TLS 1.3 [RFC8446], to convey Evidence
   that is otherwise unprotected (e.g., not signed) undermines all
   security of remote attestation.  Essentially, this breaks the chain
   up to the trust anchor (such as hardware manufacturer) for remote
   attestation.  Hence, remote attestation effectively provides no
   protection in this case and the security guarantees are limited to
   those of the conveyance protocol only.  In order to benefit from
   remote attestation, Evidence MUST be protected using dedicated keys
   chaining back to the trust anchor for remote attestation.




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5.1.2.  Missing Roles and Conceptual Messages

   *  Identity Supplier and its corresponding conceptual message
      Identity are missing and need to be added to the architecture
      [Tech-Concepts].

   *  Attestation Challenge as conceptual message needs to be added to
      the architecture [Tech-Concepts].

6.  Examples of Specifications That Are Detrimental for Security

   We believe that the following drafts are detrimental for the RATS
   ecosystem:

   *  Multi-Verifiers [I-D.deshpande-rats-multi-verifier]: the design of
      multi-verifiers not only increase security risks in terms of
      increasing the Trusted Computing Base (TCB), but also increases
      the privacy risks, as potentially sensitive information is sent to
      multiple verifiers.

   *  Aggregator-based design [I-D.ietf-rats-coserv]: Aggregator is an
      explicit trust anchor and the addition of new trust anchor needs
      to have a strong justification.

7.  Security Considerations

   All of this document is about security considerations.

8.  IANA Considerations

   This document has no IANA actions.

9.  References

9.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/rfc/rfc2119>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.







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   [RFC9334]  Birkholz, H., Thaler, D., Richardson, M., Smith, N., and
              W. Pan, "Remote ATtestation procedureS (RATS)
              Architecture", RFC 9334, DOI 10.17487/RFC9334, January
              2023, <https://www.rfc-editor.org/rfc/rfc9334>.

9.2.  Informative References

   [Gen-Approach]
              Sardar, M. U., "Perspicuity of Attestation Mechanisms in
              Confidential Computing: General Approach", October 2025,
              <https://www.researchgate.net/publication/396593308_Perspi
              cuity_of_Attestation_Mechanisms_in_Confidential_Computing_
              General_Approach>.

   [I-D.deshpande-rats-multi-verifier]
              Deshpande, Y., jun, Z., Labiod, H., and H. Birkholz,
              "Remote Attestation with Multiple Verifiers", Work in
              Progress, Internet-Draft, draft-deshpande-rats-multi-
              verifier-03, 20 October 2025,
              <https://datatracker.ietf.org/doc/html/draft-deshpande-
              rats-multi-verifier-03>.

   [I-D.ietf-rats-coserv]
              Howard, P., Fossati, T., Birkholz, H., Kamal, S., Mandyam,
              G., and D. Ma, "Concise Selector for Endorsements and
              Reference Values", Work in Progress, Internet-Draft,
              draft-ietf-rats-coserv-02, 20 October 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-rats-
              coserv-02>.

   [I-D.irtf-cfrg-cryptography-specification]
              Sullivan, N. and C. A. Wood, "Guidelines for Writing
              Cryptography Specifications", Work in Progress, Internet-
              Draft, draft-irtf-cfrg-cryptography-specification-02, 7
              July 2025, <https://datatracker.ietf.org/doc/html/draft-
              irtf-cfrg-cryptography-specification-02>.

   [Meeting-122-TLS-Slides]
              Sardar, M. U., Moustafa, M., and T. Aura, "Identity Crisis
              in Attested TLS for Confidential Computing", March 2025,
              <https://datatracker.ietf.org/meeting/122/materials/
              slides-122-tls-identity-crisis-00>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/rfc/rfc8446>.





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   [Tech-Concepts]
              Sardar, M. U., "Perspicuity of Attestation Mechanisms in
              Confidential Computing: Technical Concepts", October 2025,
              <https://www.researchgate.net/publication/396199290_Perspi
              cuity_of_Attestation_Mechanisms_in_Confidential_Computing_
              Technical_Concepts>.

Acknowledgments

   The author wishes to thank Ira McDonald for insightful discussion.
   The author also gratefully acknowledges the authors of
   [I-D.irtf-cfrg-cryptography-specification], which serves as the
   inspiration of this work.

Author's Address

   Muhammad Usama Sardar
   TU Dresden
   Email: muhammad_usama.sardar@tu-dresden.de
































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