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AEGIS-based Cipher Suites for TLS 1.3, DTLS 1.3 and QUIC
draft-denis-tls-aegis-02

Document Type Active Internet-Draft (individual)
Authors Frank Denis , Samuel Lucas
Last updated 2024-06-02
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draft-denis-tls-aegis-02
Transport Layer Security                                        F. Denis
Internet-Draft                                               Fastly Inc.
Intended status: Informational                                  S. Lucas
Expires: 4 December 2024                          Individual Contributor
                                                             2 June 2024

        AEGIS-based Cipher Suites for TLS 1.3, DTLS 1.3 and QUIC
                        draft-denis-tls-aegis-02

Abstract

   This document proposes new cipher suites based on the AEGIS family of
   authenticated encryption algorithms for integration into the TLS 1.3,
   DTLS 1.3, and QUIC protocols.

About This Document

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

   Status information for this document may be found at
   https://datatracker.ietf.org/doc/draft-denis-tls-aegis/.

   Source for this draft and an issue tracker can be found at
   https://github.com/jedisct1/draft-denis-tls-aegis.

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 4 December 2024.

Copyright Notice

   Copyright (c) 2024 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 and rationale  . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   3
   3.  New Cipher Suites and Preservation of TLS 1.3 Mechanisms  . .   3
   4.  DTLS 1.3 Record Number Encryption . . . . . . . . . . . . . .   4
   5.  QUIC Header Protection  . . . . . . . . . . . . . . . . . . .   5
   6.  Operational Considerations  . . . . . . . . . . . . . . . . .   5
   7.  Implementation Status . . . . . . . . . . . . . . . . . . . .   5
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   6
     10.2.  Informative References . . . . . . . . . . . . . . . . .   7
   Appendix A.  Examples . . . . . . . . . . . . . . . . . . . . . .   7
     A.1.  TLS 1.3 Handshake . . . . . . . . . . . . . . . . . . . .   7
       A.1.1.  With TLS_AEGIS_128L_SHA256  . . . . . . . . . . . . .   7
       A.1.2.  With TLS_AEGIS_256_SHA512 . . . . . . . . . . . . . .   8
     A.2.  DTLS 1.3 and QUIC Header Protection Mask  . . . . . . . .   8
       A.2.1.  With TLS_AEGIS_128L_SHA256  . . . . . . . . . . . . .   8
       A.2.2.  With TLS_AEGIS_128X2_SHA256 . . . . . . . . . . . . .   9
       A.2.3.  With TLS_AEGIS_256_SHA512 . . . . . . . . . . . . . .   9
       A.2.4.  With TLS_AEGIS_256X2_SHA512 . . . . . . . . . . . . .   9
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .   9
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction and rationale

   AEGIS [I-D.irtf-cfrg-aegis-aead] is a family of authenticated
   encryption algorithms designed for high-performance applications.
   AEGIS caters to the same hardware class as AES-GCM, distinguishing
   itself through the following key attributes:

   1.  Reduced memory requirements: AEGIS eliminates the necessity for a
       key schedule and precomputation tables, resulting in lower memory
       demands.  This characteristic proves particularly advantageous
       for servers managing a substantial volume of connections.

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   2.  Extended usage limits: AEGIS features higher usage limits,
       mitigating the need for frequent rekeying compared to other
       available options.

   3.  Enhanced overall performance: AEGIS is very efficient on CPUs
       supporting AES-specific instructions.

   AEGIS ciphers seamlessly integrate into established protocols like
   TLS 1.3 by adhering to the same interface standards as existing
   algorithms.

   This document introduces new cipher suites based on the AEGIS
   algorithms and outlines the procedures for their incorporation into
   the TLS 1.3 [RFC8446], DTLS 1.3 [RFC9147], and QUIC [RFC9000]
   protocols.

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.

3.  New Cipher Suites and Preservation of TLS 1.3 Mechanisms

   The TLS 1.3 protocol includes a set of mandatory cipher suites listed
   in [RFC8446], Section 9.1.

   Each cipher suite denotes the Authenticated Encryption with
   Associated Data (AEAD) algorithm for record protection, along with
   the designated hash algorithm for use with the HMAC-based Key
   Derivation Function (HKDF).

   The cipher suites and cryptographic negotiation mechanisms
   established in TLS 1.3 are reused by the DTLS 1.3 and QUIC protocols.

   To accommodate AEGIS-based encryption algorithms, this document
   introduces additional cipher suites to those specified in [RFC8446],
   Section 9.1:

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   +========================+=============+=========+=================+
   | Cipher Suite Name      | AEAD        |Hash     | Confidentiality |
   |                        | Algorithm   |Algorithm| Level           |
   +========================+=============+=========+=================+
   | TLS_AEGIS_128L_SHA256  | AEGIS-128L  |SHA256   | 128 bits        |
   +------------------------+-------------+---------+-----------------+
   | TLS_AEGIS_128X2_SHA256 | AEGIS-128X2 |SHA256   | 128 bits        |
   +------------------------+-------------+---------+-----------------+
   | TLS_AEGIS_256_SHA512   | AEGIS-256   |SHA512   | 256 bits        |
   +------------------------+-------------+---------+-----------------+
   | TLS_AEGIS_256X2_SHA512 | AEGIS-256X2 |SHA512   | 256 bits        |
   +------------------------+-------------+---------+-----------------+

               Table 1: Proposed AEGIS-based cipher suites

   The rationale behind recommending the SHA512 hash function for
   variants employing a 256-bit key is based on the findings presented
   in [M23].

   AEGIS algorithms support both 128-bit and 256-bit authentication
   tags.  For all the cipher suites referenced herein, these algorithms
   MUST be utilized with a 128-bit authentication tag.

   With the inclusion of these new cipher suites, the cryptographic
   negotiation mechanism in TLS 1.3, as outlined in [RFC8446],
   Section 4.1.1, remains unchanged, as does the record payload
   protection mechanism specified in [RFC8446], Section 5.2.

4.  DTLS 1.3 Record Number Encryption

   In DTLS 1.3, encryption of record sequence numbers follows the
   specifications detailed in [RFC9147], Section 4.2.3.

   For AEGIS-based cipher suites, the mask is generated using the AEGIS
   Stream and ZeroPad functions defined in [I-D.irtf-cfrg-aegis-aead]
   with:

   *  a 128-bit tag length

   *  sn_key, as defined in [RFC9147], Section 4.2.3

   *  ciphertext[0..16]: the first 16 bytes of the DTLS ciphertext

   *  nonce_len: the AEGIS nonce length, either 128 or 256 bits,
      depending on the chosen AEAD algorithm.

   A 48-bit mask is computed as follows:

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   mask = Stream(48, sn_key, ZeroPad(ciphertext[0..16], nonce_len))

5.  QUIC Header Protection

   In QUIC, specific segments of the QUIC packet headers undergo
   encryption in accordance with the specifications outlined in
   [RFC9001], Section 5.4.

   For AEGIS-based cipher suites, the mask is generated following the
   same procedure as in DTLS 1.3, utilizing:

   *  a 128-bit tag length

   *  hp_key, as defined in [RFC9001], Section 5.4

   *  ciphertext[0..16]: the first 16 bytes of the ciphertext

   *  nonce_len: the AEGIS nonce length, either 128 or 256 bits,
      depending on the selected AEAD algorithm.

   A 48-bit mask is computed as follows:

   mask = Stream(48, hp_key, ZeroPad(ciphertext[0..16], nonce_len))

6.  Operational Considerations

   On devices lacking hardware AES acceleration or protection against
   side-channel attacks, cipher suites dependent on the AES round
   function SHOULD NOT be prioritized.  This recommendation encompasses
   the cipher suites outlined in this document

   On devices equipped with secure hardware AES acceleration,
   implementations SHOULD prioritize AEGIS-based cipher suites over AES-
   GCM ones of equivalent security levels.

7.  Implementation Status

   _This note is to be removed before publishing as an RFC._

   A list of early implementations can be found at
   https://github.com/jedisct1/draft-denis-tls-aead.

8.  Security Considerations

   A key update MUST be performed prior to encrypting 2^48 records with
   the same key.  The prescribed mechanism is documented in [RFC8446],
   Section 4.6.3.

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9.  IANA Considerations

   IANA is requested to register the following identifiers in the TLS
   Cipher Suite Registry:

            +========================+=========+=============+
            | Description            | DTLS-OK | Recommended |
            +========================+=========+=============+
            | TLS_AEGIS_128L_SHA256  |    Y    |      N      |
            +------------------------+---------+-------------+
            | TLS_AEGIS_128X2_SHA512 |    Y    |      N      |
            +------------------------+---------+-------------+
            | TLS_AEGIS_256_SHA256   |    Y    |      N      |
            +------------------------+---------+-------------+
            | TLS_AEGIS_256X2_SHA512 |    Y    |      N      |
            +------------------------+---------+-------------+

                   Table 2: Requested IANA identifiers

10.  References

10.1.  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>.

   [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>.

   [RFC9000]  Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
              Multiplexed and Secure Transport", RFC 9000,
              DOI 10.17487/RFC9000, May 2021,
              <https://www.rfc-editor.org/rfc/rfc9000>.

   [RFC9001]  Thomson, M., Ed. and S. Turner, Ed., "Using TLS to Secure
              QUIC", RFC 9001, DOI 10.17487/RFC9001, May 2021,
              <https://www.rfc-editor.org/rfc/rfc9001>.

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   [RFC9147]  Rescorla, E., Tschofenig, H., and N. Modadugu, "The
              Datagram Transport Layer Security (DTLS) Protocol Version
              1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022,
              <https://www.rfc-editor.org/rfc/rfc9147>.

10.2.  Informative References

   [I-D.irtf-cfrg-aegis-aead]
              Denis, F. and S. Lucas, "The AEGIS Family of Authenticated
              Encryption Algorithms", Work in Progress, Internet-Draft,
              draft-irtf-cfrg-aegis-aead-10, 20 January 2024,
              <https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-
              aegis-aead-10>.

   [M23]      Mattsson, J. P., "Hidden Stream Ciphers and TMTO Attacks
              on TLS 1.3, DTLS 1.3, QUIC, and Signal", Cryptology ePrint
              Archive, Paper 2023/913, DOI 10.1007/978-981-99-7563-1_12,
              2023, <https://eprint.iacr.org/2023/913.pdf>.

Appendix A.  Examples

A.1.  TLS 1.3 Handshake

A.1.1.  With TLS_AEGIS_128L_SHA256

   shared_key:           cbb2b72da2bc70eb85fae05a8f6bc929
                         6f3e2f9693e5972a7b2a3da608e5eda2

   hello_hash:           b77594edb8abd3acc4db7f5ead5869e1
                         96fff7d0fb1beb2bffbaac850bf479d8

   early_secret:         33ad0a1c607ec03b09e6cd9893680ce2
                         10adf300aa1f2660e1b22e10f170f92a

   handshake_secret:     15614a4e6a6c590f16e9760dc20002a1
                         2af27d6ceda73c66a9477de4b690639f

   client_secret:        6e60b228fdd7c8b08ac50e5018fa79ec
                         3f8cd2ee023386111b0d7a2027e5c1b8

   client_handshake_key: 2474bdcd8e8c8dff18af9e169e4470ea

   client_handshake_iv:  42fe48bd086cc5ddaf43be4500d0c7f2

   server_handshake_key: e0d7ea14104a89cfdf253e1f0e0302b0

   server_handshake_iv:  cc421814028367299508e120a7cb3ad2

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A.1.2.  With TLS_AEGIS_256_SHA512

   shared_key:           724d41a7ccadc6435d4305dd6756bd01
                         5e26dd0544a19733a2c08430f128b218

   hello_hash:           1a8fd72e2630e12817d768bae1248367
                         30c07141c4ab4cc3423d7f16c3c1a84b
                         91d4c4194453dbc85fca8738b4e9ea3c
                         783bb6d99f579fd6c2f599c69c1c79e1

   early_secret:         fd4a40cb6252b3c08d9b88d5bde85339
                         03caa51a1dba1c79ce18eea0365d35d0
                         71e597a2b95214821100e812f7b79828
                         498f164707cd63c6f7464973cfa22046

   handshake_secret:     55ef8c23352da78bf1daa4626445c883
                         b842bec578769fe9ae6fbf6de5c28953
                         02ec3cbb22b3a94ea1d047ab08cce64e
                         1079f3dbc9bf08152dc3b0bcd74ac977

   client_secret:        728f1edab4426f4dac3f03180b0bc537
                         a0d555514b439ea4f4cccb5910834807
                         408d29b9c79dcbff8e3a3fb8bf220907
                         d96ce595eee7ffaf9f9735e4f6da1e60

   client_handshake_key: 08a37693b14937177d75149422944c34
                         9019de948f6922c2c516d941c0bdafe4

   client_handshake_iv:  e0a2155fedcb592a29588bdcf06334f0
                         4dc6b5c40e659051e62071cb87f8be2c

   server_handshake_key: 366e1ebfb124508aa69137ccef542756
                         c0a748525c5bdc16acd79c66856e7c82

   server_handshake_iv:  8f883c1bb0eae38960efdb717f6b19cf
                         c929d565ad596f1f4b3daab498a7fc29

A.2.  DTLS 1.3 and QUIC Header Protection Mask

A.2.1.  With TLS_AEGIS_128L_SHA256

   key:                  000102030405060708090a0b0c0d0e0f

   ciphertext[0..16]:    101112131415161718191a1b1c1d1e1f

   nonce_len:            128 bits

   mask:                 60ede1c811

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A.2.2.  With TLS_AEGIS_128X2_SHA256

   key:                  000102030405060708090a0b0c0d0e0f

   ciphertext[0..16]:    101112131415161718191a1b1c1d1e1f

   nonce_len:            128 bits

   mask:                 6bf2292472

A.2.3.  With TLS_AEGIS_256_SHA512

   key:                  000102030405060708090a0b0c0d0e0f
                         101112131415161718191a1b1c1d1e1f

   ciphertext[0..16]:    202122232425262728292a2b2c2d2e2f

   nonce_len:            256 bits

   mask:                 6e3a2ce297

A.2.4.  With TLS_AEGIS_256X2_SHA512

   key:                  000102030405060708090a0b0c0d0e0f
                         101112131415161718191a1b1c1d1e1f

   ciphertext[0..16]:    202122232425262728292a2b2c2d2e2f

   nonce_len:            256 bits

   mask:                 7a515cfb0c

Acknowledgments

   We would like to thank John Preuß Mattsson for suggesting how AEGIS
   should be used in the context of DTLS and QUIC.

Authors' Addresses

   Frank Denis
   Fastly Inc.
   Email: fde@00f.net

   Samuel Lucas
   Individual Contributor
   Email: samuel-lucas6@pm.me

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