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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 November 18, 2020 5 Expires: May 22, 2021 7 SCRAM-SHA-512 and SCRAM-SHA-512-PLUS Simple Authentication and Security 8 Layer (SASL) Mechanisms 9 draft-melnikov-scram-sha-512-01 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 May 22, 2021. 33 Copyright Notice 35 Copyright (c) 2020 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 40 (https://trustee.ietf.org/license-info) in effect on the date of 41 publication of this document. Please review these documents 42 carefully, as they describe your rights and restrictions with respect 43 to this document. Code Components extracted from this document must 44 include Simplified BSD License text as described in Section 4.e of 45 the Trust Legal Provisions and are provided without warranty as 46 described in the Simplified BSD License. 48 Table of Contents 50 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 51 2. Key Word Definitions . . . . . . . . . . . . . . . . . . . . 2 52 3. SCRAM-SHA-512 and SCRAM-SHA-512-PLUS . . . . . . . . . . . . 2 53 4. Security Considerations . . . . . . . . . . . . . . . . . . . 3 54 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 55 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 56 6.1. Normative References . . . . . . . . . . . . . . . . . . 4 57 6.2. Informative References . . . . . . . . . . . . . . . . . 5 58 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 7 59 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7 61 1. Introduction 63 This document registers the SASL [RFC4422] mechanisms SCRAM-SHA-512 64 and SCRAM-SHA-512-PLUS. SHA-512 has stronger security properties 65 than SHA-1, and it is expected that SCRAM mechanisms based on it will 66 have greater predicted longevity than the SCRAM mechanisms based on 67 SHA-1. 69 2. Key Word Definitions 71 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 72 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 73 "OPTIONAL" in this document are to be interpreted as described in BCP 74 14 [RFC2119] [RFC8174] when, and only when, they appear in all 76 3. SCRAM-SHA-512 and SCRAM-SHA-512-PLUS 78 The SCRAM-SHA-512 and SCRAM-SHA-512-PLUS SASL mechanisms are defined 79 in the same way that SCRAM-SHA-1 and SCRAM-SHA-1-PLUS are defined in 80 [RFC5802], except that the hash function for HMAC() and H() uses 81 SHA-512 instead of SHA-1 [RFC6234]. 83 For the SCRAM-SHA-512 and SCRAM-SHA-512-PLUS SASL mechanisms, the 84 hash iteration-count announced by a server SHOULD be at least 10000. 86 The GSS-API mechanism OID for SCRAM-SHA-512 is 1.3.6.1.5.5. (see 87 Section 5). 89 This is a simple example of a SCRAM-SHA-512 authentication exchange 90 when the client doesn't support channel bindings. The username 91 'user' and password 'pencil' are being used. 93 [[TBD: Add an example]] 95 4. Security Considerations 97 The security considerations from [RFC5802] still apply. 99 To be secure, either SCRAM-SHA-512-PLUS and SCRAM-SHA-1-PLUS MUST be 100 used over a TLS channel that has had the session hash extension 101 [RFC7627] negotiated, or session resumption MUST NOT have been used. 102 When using SCRAM over TLS 1.2 [RFC5246], the "tls-unique" channel 103 binding is still the default channel binding to use (see Section 6.1 104 of [RFC5802]), assuming the above conditions are satisfied. As "tls- 105 unique" channel binding is not defined for TLS 1.3 [RFC8446], when 106 using SCRAM over TLS 1.3, the "tls-exporter" channel binding 107 [tls-1.3-channel-binding] MUST be the default channel binding (in the 108 sense specified in Section 6.1 of [RFC5802]) to use. 110 See [RFC4270] and [RFC6194] for reasons to move from SHA-1 to a 111 strong security mechanism like SHA-512. 113 The strength of this mechanism is dependent in part on the hash 114 iteration-count, as denoted by "i" in [RFC5802]. As a rule of thumb, 115 the hash iteration-count should be such that a modern machine will 116 take 0.1 seconds to perform the complete algorithm; however, this is 117 unlikely to be practical on mobile devices and other relatively low- 118 performance systems. At the time this was written, the rule of thumb 119 gives around 15,000 iterations required; however, a hash iteration- 120 count of 10000 takes around 0.5 seconds on current mobile handsets. 121 This computational cost can be avoided by caching the ClientKey 122 (assuming the Salt and hash iteration-count is stable). Therefore, 123 the recommendation of this specification is that the hash iteration- 124 count SHOULD be at least 10000, but careful consideration ought to be 125 given to using a significantly higher value, particularly where 126 mobile use is less important. 128 5. IANA Considerations 130 IANA is requested to add the following new SASL SCRAM mechanisms to 131 the "SASL SCRAM Family Mechanisms" registry: 133 To: iana@iana.org 135 Subject: Registration of a new SASL SCRAM Family mechanism SCRAM- 136 SHA-512 138 SASL mechanism name (or prefix for the family): SCRAM-SHA-512 140 Security considerations: Section 4 of RFC XXXX 141 Published specification (optional, recommended): RFC XXXX 143 Minimum iteration-count: 10000 145 OID: 1.3.6.1.5.5. 147 Person & email address to contact for further information: IETF 148 KITTEN WG 150 Intended usage: COMMON 152 Owner/Change controller: IESG 154 Note: 156 To: iana@iana.org 158 Subject: Registration of a new SASL SCRAM Family mechanism SCRAM- 159 SHA-512-PLUS 161 SASL mechanism name (or prefix for the family): SCRAM-SHA- 162 512-PLUS 164 Security considerations: Section 4 of RFC XXXX 166 Published specification (optional, recommended): RFC XXXX 168 Minimum iteration-count: 10000 170 OID: 1.3.6.1.5.5. 172 Person & email address to contact for further information: IETF 173 KITTEN WG 175 Intended usage: COMMON 177 Owner/Change controller: IESG 179 Note: 181 6. References 183 6.1. Normative References 185 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 186 Requirement Levels", BCP 14, RFC 2119, 187 DOI 10.17487/RFC2119, March 1997, 188 . 190 [RFC4422] Melnikov, A., Ed. and K. Zeilenga, Ed., "Simple 191 Authentication and Security Layer (SASL)", RFC 4422, 192 DOI 10.17487/RFC4422, June 2006, 193 . 195 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 196 (TLS) Protocol Version 1.2", RFC 5246, 197 DOI 10.17487/RFC5246, August 2008, 198 . 200 [RFC5802] Newman, C., Menon-Sen, A., Melnikov, A., and N. Williams, 201 "Salted Challenge Response Authentication Mechanism 202 (SCRAM) SASL and GSS-API Mechanisms", RFC 5802, 203 DOI 10.17487/RFC5802, July 2010, 204 . 206 [RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms 207 (SHA and SHA-based HMAC and HKDF)", RFC 6234, 208 DOI 10.17487/RFC6234, May 2011, 209 . 211 [RFC7627] Bhargavan, K., Ed., Delignat-Lavaud, A., Pironti, A., 212 Langley, A., and M. Ray, "Transport Layer Security (TLS) 213 Session Hash and Extended Master Secret Extension", 214 RFC 7627, DOI 10.17487/RFC7627, September 2015, 215 . 217 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 218 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 219 May 2017, . 221 [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol 222 Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, 223 . 225 [tls-1.3-channel-binding] 226 Whited, S., "Channel Bindings for TLS 1.3", draft-ietf- 227 kitten-tls-channel-bindings-for-tls13-00 (work in 228 progress), June 2020. 230 6.2. Informative References 232 [RFC4270] Hoffman, P. and B. Schneier, "Attacks on Cryptographic 233 Hashes in Internet Protocols", RFC 4270, 234 DOI 10.17487/RFC4270, November 2005, 235 . 237 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 238 IANA Considerations Section in RFCs", RFC 5226, 239 DOI 10.17487/RFC5226, May 2008, 240 . 242 [RFC6194] Polk, T., Chen, L., Turner, S., and P. Hoffman, "Security 243 Considerations for the SHA-0 and SHA-1 Message-Digest 244 Algorithms", RFC 6194, DOI 10.17487/RFC6194, March 2011, 245 . 247 Acknowledgements 249 This document is based on RFC 7677 by Tony Hansen. 251 Author's Address 253 Alexey Melnikov (editor) 254 Isode Ltd 255 14 Castle Mews 256 Hampton, Middlesex TW12 2NP 257 UK 259 EMail: alexey.melnikov@isode.com