Network Working Group L. Velvindron Internet-Draft cyberstorm.mu Updates: 8314 (if approved) S. Farrell Intended status: Standards Track Trinity College Dublin Expires: May 30, 2019 November 26, 2018 Use of TLS for Email Submission and Access draft-ietf-uta-tls-for-email-00 Abstract This specification updates current recommendation for the use of Transport Layer Security (TLS) protocol to provide confidentiality of email between a Mail User Agent (MUA) and a Mail Submission Server or Mail Access Server. This document updates RFC8314. 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/. 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Velvindron & Farrell Expires May 30, 2019 [Page 1] Internet-Draft TLS For Email November 2018 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions Used in This Document . . . . . . . . . . . . . . 2 3. Updates to RFC8314 . . . . . . . . . . . . . . . . . . . . . 2 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 6.1. Informative References . . . . . . . . . . . . . . . . . 4 6.2. Normative References . . . . . . . . . . . . . . . . . . 4 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 1. Introduction [RFC8314] defines the minimum recommended version for TLS as version 1.1. Due to the deprecation of TLS 1.1 in [I-D.ietf-tls-oldversions-deprecate], this recommendation is no longer valid. Therefore this document updates [RFC8314] so that the minimum version for TLS is TLS 1.2. 2. Conventions Used in This Document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119] when they appear in ALL CAPS. These words may also appear in this document in lower case as plain English words, absent their normative meanings. 3. Updates to RFC8314 OLD: "4.1. Deprecation of Services Using Cleartext and TLS Versions Less Than 1.1" NEW: "4.1. Deprecation of Services Using Cleartext and TLS Versions Less Than 1.2" OLD "As soon as practicable, MSPs currently supporting Secure Sockets Layer (SSL) 2.x, SSL 3.0, or TLS 1.0 SHOULD transition their users to TLS 1.1 or later and discontinue support for those earlier versions of SSL and TLS." NEW: Velvindron & Farrell Expires May 30, 2019 [Page 2] Internet-Draft TLS For Email November 2018 "As soon as practicable, MSPs currently supporting Secure Sockets Layer (SSL) 2.x, SSL 3.0, or TLS 1.0 SHOULD transition their users to TLS 1.2 or later and discontinue support for those earlier versions of SSL and TLS." OLD: In Section 4.1, the text should be revised from: "It is RECOMMENDED that new users be required to use TLS version 1.1 or greater from the start. However, an MSP may find it necessary to make exceptions to accommodate some legacy systems that support only earlier versions of TLS or only cleartext." NEW: "It is RECOMMENDED that new users be required to use TLS version 1.2 or greater from the start. However, an MSP may find it necessary to make exceptions to accommodate some legacy systems that support only earlier versions of TLS or only cleartext." OLD: " If, however, an MUA provides such an indication, it MUST NOT indicate confidentiality for any connection that does not at least use TLS 1.1 with certificate verification and also meet the minimum confidentiality requirements associated with that account. " NEW: " If, however, an MUA provides such an indication, it MUST NOT indicate confidentiality for any connection that does not at least use TLS 1.2 with certificate verification and also meet the minimum confidentiality requirements associated with that account. " OLD " MUAs MUST implement TLS 1.2 [RFC5246] or later. Earlier TLS and SSL versions MAY also be supported, so long as the MUA requires at least TLS 1.1 [RFC4346] when accessing accounts that are configured to impose minimum confidentiality requirements. " NEW: " MUAs MUST implement TLS 1.2 [RFC5246] or later e.g TLS 1.3 [RFC8446]. Earlier TLS and SSL versions MAY also be supported, so long as the MUA requires at least TLS 1.2 [RFC5246] when accessing accounts that are configured to impose minimum confidentiality requirements. " Velvindron & Farrell Expires May 30, 2019 [Page 3] Internet-Draft TLS For Email November 2018 OLD: " The default minimum expected level of confidentiality for all new accounts MUST require successful validation of the server's certificate and SHOULD require negotiation of TLS version 1.2 or greater. (Future revisions to this specification may raise these requirements or impose additional requirements to address newly discovered weaknesses in protocols or cryptographic algorithms. " NEW: " The default minimum expected level of confidentiality for all new accounts MUST require successful validation of the server's certificate and SHOULD require negotiation of TLS version 1.2 or greater. (Future revisions to this specification may raise these requirements or impose additional requirements to address newly discovered weaknesses in protocols or cryptographic algorithms. " 4. IANA Considerations None of the proposed measures have an impact on IANA. 5. Security Considerations The purpose of this document is to document updated recommendations for using TLS with Email services. Those recommendations are based on [I-D.ietf-tls-oldversions-deprecate]. 6. References 6.1. Informative References [RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.1", RFC 4346, DOI 10.17487/RFC4346, April 2006, . 6.2. Normative References [I-D.ietf-tls-oldversions-deprecate] Moriarty, K. and S. Farrell, "Deprecating TLSv1.0 and TLSv1.1", draft-ietf-tls-oldversions-deprecate-01 (work in progress), November 2018. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . Velvindron & Farrell Expires May 30, 2019 [Page 4] Internet-Draft TLS For Email November 2018 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/RFC5246, August 2008, . [RFC8314] Moore, K. and C. Newman, "Cleartext Considered Obsolete: Use of Transport Layer Security (TLS) for Email Submission and Access", RFC 8314, DOI 10.17487/RFC8314, January 2018, . [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, . Authors' Addresses Loganaden Velvindron cyberstorm.mu 88 Avenue De Plevitz Roches Brunes Rose Hill 71259 Mauritius Phone: +230 59762817 Email: loganaden@gmail.com Stephen Farrell Trinity College Dublin Dublin 2 Ireland Phone: +353-1-896-2354 Email: stephen.farrell@cs.tcd.ie Velvindron & Farrell Expires May 30, 2019 [Page 5]