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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group A. Melnikov, Ed. 3 Internet-Draft Isode Ltd 4 Intended status: Standards Track 19 October 2021 5 Expires: 22 April 2022 7 SCRAM-SHA-512 and SCRAM-SHA-512-PLUS Simple Authentication and Security 8 Layer (SASL) Mechanisms 9 draft-melnikov-scram-sha-512-02 11 Abstract 13 This document registers the Simple Authentication and Security Layer 14 (SASL) mechanisms SCRAM-SHA-512 and SCRAM-SHA-512-PLUS. 16 Status of This Memo 18 This Internet-Draft is submitted in full conformance with the 19 provisions of BCP 78 and BCP 79. 21 Internet-Drafts are working documents of the Internet Engineering 22 Task Force (IETF). Note that other groups may also distribute 23 working documents as Internet-Drafts. The list of current Internet- 24 Drafts is at https://datatracker.ietf.org/drafts/current/. 26 Internet-Drafts are draft documents valid for a maximum of six months 27 and may be updated, replaced, or obsoleted by other documents at any 28 time. It is inappropriate to use Internet-Drafts as reference 29 material or to cite them other than as "work in progress." 31 This Internet-Draft will expire on 22 April 2022. 33 Copyright Notice 35 Copyright (c) 2021 IETF Trust and the persons identified as the 36 document authors. All rights reserved. 38 This document is subject to BCP 78 and the IETF Trust's Legal 39 Provisions Relating to IETF Documents (https://trustee.ietf.org/ 40 license-info) in effect on the date of publication of this document. 41 Please review these documents carefully, as they describe your rights 42 and restrictions with respect to this document. Code Components 43 extracted from this document must include Simplified BSD License text 44 as described in Section 4.e of the Trust Legal Provisions and are 45 provided without warranty as described in the Simplified BSD License. 47 Table of Contents 49 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 50 2. Key Word Definitions . . . . . . . . . . . . . . . . . . . . 2 51 3. SCRAM-SHA-512 and SCRAM-SHA-512-PLUS . . . . . . . . . . . . 2 52 4. Security Considerations . . . . . . . . . . . . . . . . . . . 3 53 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 54 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 55 6.1. Normative References . . . . . . . . . . . . . . . . . . 4 56 6.2. Informative References . . . . . . . . . . . . . . . . . 5 57 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 6 58 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6 60 1. Introduction 62 This document registers the SASL [RFC4422] mechanisms SCRAM-SHA-512 63 and SCRAM-SHA-512-PLUS. SHA-512 has stronger security properties 64 than SHA-1, and it is expected that SCRAM mechanisms based on it will 65 have greater predicted longevity than the SCRAM mechanisms based on 66 SHA-1. 68 2. Key Word Definitions 70 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 71 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 72 "OPTIONAL" in this document are to be interpreted as described in BCP 73 14 [RFC2119] [RFC8174] when, and only when, they appear in all 75 3. SCRAM-SHA-512 and SCRAM-SHA-512-PLUS 77 The SCRAM-SHA-512 and SCRAM-SHA-512-PLUS SASL mechanisms are defined 78 in the same way that SCRAM-SHA-1 and SCRAM-SHA-1-PLUS are defined in 79 [RFC5802], except that the hash function for HMAC() and H() uses 80 SHA-512 instead of SHA-1 [RFC6234]. 82 For the SCRAM-SHA-512 and SCRAM-SHA-512-PLUS SASL mechanisms, the 83 hash iteration-count announced by a server SHOULD be at least 10000. 85 The GSS-API mechanism OID for SCRAM-SHA-512 is 1.3.6.1.5.5. (see 86 Section 5). 88 This is a simple example of a SCRAM-SHA-512 authentication exchange 89 when the client doesn't support channel bindings. The username 90 'user' and password 'pencil' are being used. 92 [[TBD: Add an example]] 94 4. Security Considerations 96 The security considerations from [RFC5802] still apply. 98 To be secure, SCRAM-SHA-512-PLUS MUST be used over a TLS channel that 99 has had the session hash extension [RFC7627] negotiated, or session 100 resumption MUST NOT have been used. When using SCRAM over TLS 1.2 101 [RFC5246], the "tls-unique" channel binding is still the default 102 channel binding to use (see Section 6.1 of [RFC5802]), assuming the 103 above conditions are satisfied. As "tls-unique" channel binding is 104 not defined for TLS 1.3 [RFC8446], when using SCRAM over TLS 1.3, the 105 "tls-exporter" channel binding [tls-1.3-channel-binding] MUST be the 106 default channel binding (in the sense specified in Section 6.1 of 107 [RFC5802]) to use. 109 See [RFC4270] and [RFC6194] for reasons to move from SHA-1 to a 110 strong security mechanism like SHA-512. 112 The strength of this mechanism is dependent in part on the hash 113 iteration-count, as denoted by "i" in [RFC5802]. As a rule of thumb, 114 the hash iteration-count should be such that a modern machine will 115 take 0.1 seconds to perform the complete algorithm; however, this is 116 unlikely to be practical on mobile devices and other relatively low- 117 performance systems. At the time this was written, the rule of thumb 118 gives around 15,000 iterations required; however, a hash iteration- 119 count of 10000 takes around 0.5 seconds on current mobile handsets. 120 This computational cost can be avoided by caching the ClientKey 121 (assuming the Salt and hash iteration-count is stable). Therefore, 122 the recommendation of this specification is that the hash iteration- 123 count SHOULD be at least 10000, but careful consideration ought to be 124 given to using a significantly higher value, particularly where 125 mobile use is less important. 127 5. IANA Considerations 129 IANA is requested to add the following new SASL SCRAM mechanisms to 130 the "SASL SCRAM Family Mechanisms" registry: 132 To: iana@iana.org 134 Subject: Registration of a new SASL SCRAM Family mechanism SCRAM- 135 SHA-512 137 SASL mechanism name (or prefix for the family): SCRAM-SHA-512 139 Security considerations: Section 4 of RFC XXXX 141 Published specification (optional, recommended): RFC XXXX 142 Minimum iteration-count: 10000 144 OID: 1.3.6.1.5.5. 146 Person & email address to contact for further information: IETF 147 KITTEN WG 149 Intended usage: COMMON 151 Owner/Change controller: IESG 153 Note: 155 To: iana@iana.org 157 Subject: Registration of a new SASL SCRAM Family mechanism SCRAM- 158 SHA-512-PLUS 160 SASL mechanism name (or prefix for the family): SCRAM-SHA- 161 512-PLUS 163 Security considerations: Section 4 of RFC XXXX 165 Published specification (optional, recommended): RFC XXXX 167 Minimum iteration-count: 10000 169 OID: 1.3.6.1.5.5. 171 Person & email address to contact for further information: IETF 172 KITTEN WG 174 Intended usage: COMMON 176 Owner/Change controller: IESG 178 Note: 180 6. References 182 6.1. Normative References 184 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 185 Requirement Levels", BCP 14, RFC 2119, 186 DOI 10.17487/RFC2119, March 1997, 187 . 189 [RFC4422] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple 190 Authentication and Security Layer (SASL)", RFC 4422, 191 DOI 10.17487/RFC4422, June 2006, 192 . 194 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 195 (TLS) Protocol Version 1.2", RFC 5246, 196 DOI 10.17487/RFC5246, August 2008, 197 . 199 [RFC5802] Newman, C., Menon-Sen, A., Melnikov, A., and N. Williams, 200 "Salted Challenge Response Authentication Mechanism 201 (SCRAM) SASL and GSS-API Mechanisms", RFC 5802, 202 DOI 10.17487/RFC5802, July 2010, 203 . 205 [RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms 206 (SHA and SHA-based HMAC and HKDF)", RFC 6234, 207 DOI 10.17487/RFC6234, May 2011, 208 . 210 [RFC7627] Bhargavan, K., Ed., Delignat-Lavaud, A., Pironti, A., 211 Langley, A., and M. Ray, "Transport Layer Security (TLS) 212 Session Hash and Extended Master Secret Extension", 213 RFC 7627, DOI 10.17487/RFC7627, September 2015, 214 . 216 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 217 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 218 May 2017, . 220 [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol 221 Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, 222 . 224 [tls-1.3-channel-binding] 225 Whited, S., "Channel Bindings for TLS 1.3", Work in 226 Progress, Internet-Draft, draft-ietf-kitten-tls-channel- 227 bindings-for-tls13-11, 18 October 2021, 228 . 231 6.2. Informative References 233 [RFC4270] Hoffman, P. and B. Schneier, "Attacks on Cryptographic 234 Hashes in Internet Protocols", RFC 4270, 235 DOI 10.17487/RFC4270, November 2005, 236 . 238 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 239 IANA Considerations Section in RFCs", RFC 5226, 240 DOI 10.17487/RFC5226, May 2008, 241 . 243 [RFC6194] Polk, T., Chen, L., Turner, S., and P. Hoffman, "Security 244 Considerations for the SHA-0 and SHA-1 Message-Digest 245 Algorithms", RFC 6194, DOI 10.17487/RFC6194, March 2011, 246 . 248 Acknowledgements 250 This document is based on RFC 7677 by Tony Hansen. 252 Thank you to Ludovic Bocquet for comments and corrections. 254 Author's Address 256 Alexey Melnikov (editor) 257 Isode Ltd 258 14 Castle Mews 259 Hampton 260 TW12 2NP 261 United Kingdom 263 Email: alexey.melnikov@isode.com