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. Denis & Lucas Expires 4 December 2024 [Page 1] Internet-Draft draft-denis-tls-aegis-02 June 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 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. Denis & Lucas Expires 4 December 2024 [Page 2] Internet-Draft draft-denis-tls-aegis-02 June 2024 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: Denis & Lucas Expires 4 December 2024 [Page 3] Internet-Draft draft-denis-tls-aegis-02 June 2024 +========================+=============+=========+=================+ | 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: Denis & Lucas Expires 4 December 2024 [Page 4] Internet-Draft draft-denis-tls-aegis-02 June 2024 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. Denis & Lucas Expires 4 December 2024 [Page 5] Internet-Draft draft-denis-tls-aegis-02 June 2024 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, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . [RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based Multiplexed and Secure Transport", RFC 9000, DOI 10.17487/RFC9000, May 2021, . [RFC9001] Thomson, M., Ed. and S. Turner, Ed., "Using TLS to Secure QUIC", RFC 9001, DOI 10.17487/RFC9001, May 2021, . Denis & Lucas Expires 4 December 2024 [Page 6] Internet-Draft draft-denis-tls-aegis-02 June 2024 [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, . 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, . [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, . 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 Denis & Lucas Expires 4 December 2024 [Page 7] Internet-Draft draft-denis-tls-aegis-02 June 2024 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 Denis & Lucas Expires 4 December 2024 [Page 8] Internet-Draft draft-denis-tls-aegis-02 June 2024 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 Denis & Lucas Expires 4 December 2024 [Page 9]