Internet DRAFT - draft-denis-tls-aegis
draft-denis-tls-aegis
Transport Layer Security F. Denis
Internet-Draft Fastly Inc.
Intended status: Informational S. Lucas
Expires: 9 June 2024 Individual Contributor
7 December 2023
AEGIS-based Cipher Suites for TLS 1.3, DTLS 1.3 and QUIC
draft-denis-tls-aegis-01
Abstract
This documents 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.
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This Internet-Draft will expire on 9 June 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
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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. TLS 1.3 Nonces for Record Encryption . . . . . . . . . . 8
A.2.1. With TLS_AEGIS_128L_SHA256 . . . . . . . . . . . . . 8
A.2.2. With TLS_AEGIS_128L_SHA512 . . . . . . . . . . . . . 9
A.3. DTLS 1.3 and QUIC Header Protection Mask . . . . . . . . 9
A.3.1. With TLS_AEGIS_128L_SHA256 . . . . . . . . . . . . . 9
A.3.2. With TLS_AEGIS_128X2_SHA256 . . . . . . . . . . . . . 9
A.3.3. With TLS_AEGIS_256_SHA512 . . . . . . . . . . . . . . 9
A.3.4. With TLS_AEGIS_256X2_SHA512 . . . . . . . . . . . . . 9
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
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:
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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.
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 16 or 32, depending on
the chosen AEAD algorithm.
A 48-bit mask is computed as follows:
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mask = Stream(5, 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 16 or 32, depending on
the selected AEAD algorithm.
A 48-bit mask is computed as follows:
mask = Stream(5, 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-09, 5 December 2023,
<https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-
aegis-aead-09>.
[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. TLS 1.3 Nonces for Record Encryption
A.2.1. With TLS_AEGIS_128L_SHA256
handshake_iv: cc421814028367299508e120a7cb3ad2
sequence_number: 0102030405
nonce: cc421814028367299508e121a5c83ed7
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A.2.2. With TLS_AEGIS_128L_SHA512
handshake_iv: 724d41a7ccadc6435d4305dd6756bd01
5e26dd0544a19733a2c08430f128b218
sequence_number: 0102030405
nonce: 724d41a7ccadc6435d4305dd6756bd01
5e26dd0544a19733a2c08431f32bb61d
A.3. DTLS 1.3 and QUIC Header Protection Mask
A.3.1. With TLS_AEGIS_128L_SHA256
key: 000102030405060708090a0b0c0d0e0f
ciphertext[0..16]: 101112131415161718191a1b1c1d1e1f
nonce_len: 16
mask: 60ede1c811
A.3.2. With TLS_AEGIS_128X2_SHA256
key: 000102030405060708090a0b0c0d0e0f
ciphertext[0..16]: 101112131415161718191a1b1c1d1e1f
nonce_len: 16
mask: 6bf2292472
A.3.3. With TLS_AEGIS_256_SHA512
key: 000102030405060708090a0b0c0d0e0f
101112131415161718191a1b1c1d1e1f
ciphertext[0..16]: 202122232425262728292a2b2c2d2e2f
nonce_len: 32
mask: 6e3a2ce297
A.3.4. With TLS_AEGIS_256X2_SHA512
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key: 000102030405060708090a0b0c0d0e0f
101112131415161718191a1b1c1d1e1f
ciphertext[0..16]: 202122232425262728292a2b2c2d2e2f
nonce_len: 32
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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