Updated Transport Layer Security (TLS) Server Identity Check Procedure for Email-Related Protocols
RFC 7817
| Document | Type | RFC - Proposed Standard (March 2016; No errata) | |
|---|---|---|---|
| Author | Alexey Melnikov | ||
| Last updated | 2017-07-24 | ||
| Replaces | draft-melnikov-email-tls-certs | ||
| Stream | Internet Engineering Task Force (IETF) | ||
| Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Leif Johansson | ||
| Shepherd write-up | Show (last changed 2015-11-02) | ||
| IESG | IESG state | RFC 7817 (Proposed Standard) | |
| Action Holders |
(None)
|
||
| Consensus Boilerplate | Yes | ||
| Telechat date | |||
| Responsible AD | Stephen Farrell | ||
| Send notices to | "Leif Johansson" <leifj@sunet.se> | ||
| IANA | IANA review state | Version Changed - Review Needed | |
| IANA action state | No IANA Actions | ||
Internet Engineering Task Force (IETF) A. Melnikov
Request for Comments: 7817 Isode Ltd
Updates: 2595, 3207, 3501, 5804 March 2016
Category: Standards Track
ISSN: 2070-1721
Updated Transport Layer Security (TLS) Server Identity Check Procedure
for Email-Related Protocols
Abstract
This document describes the Transport Layer Security (TLS) server
identity verification procedure for SMTP Submission, IMAP, POP, and
ManageSieve clients. It replaces Section 2.4 (Server Identity Check)
of RFC 2595 and updates Section 4.1 (Processing After the STARTTLS
Command) of RFC 3207, Section 11.1 (STARTTLS Security Considerations)
of RFC 3501, and Section 2.2.1 (Server Identity Check) of RFC 5804.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7817.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://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 Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Melnikov Standards Track [Page 1]
RFC 7817 TLS Server Identity Check for Email March 2016
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
3. Email Server Certificate Verification Rules . . . . . . . . . 3
4. Compliance Checklist for Certification Authorities . . . . . 5
4.1. Notes on Handling of Delegated Email Services by
Certification Authorities . . . . . . . . . . . . . . . . 5
5. Compliance Checklist for Mail Service Providers and
Certificate Signing Request Generation Tools . . . . . . . . 6
5.1. Notes on Hosting Multiple Domains . . . . . . . . . . . . 7
6. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 8
7. Operational Considerations . . . . . . . . . . . . . . . . . 9
8. Security Considerations . . . . . . . . . . . . . . . . . . . 9
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.1. Normative References . . . . . . . . . . . . . . . . . . 9
9.2. Informative References . . . . . . . . . . . . . . . . . 11
Appendix A. Changes to RFCs 2595, 3207, 3501, and 5804 . . . . . 12
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 13
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
Use of TLS by SMTP Submission, IMAP, POP, and ManageSieve clients is
described in [RFC3207], [RFC3501], [RFC2595], and [RFC5804],
respectively. Each of the documents describes slightly different
rules for server certificate identity verification (or doesn't define
any rules at all). In reality, email client and server developers
implement many of these protocols at the same time, so it would be
good to define modern and consistent rules for verifying email server
identities using TLS.
This document describes the updated TLS server identity verification
procedure for SMTP Submission [RFC6409] [RFC3207], IMAP [RFC3501],
POP [RFC1939], and ManageSieve [RFC5804] clients. Section 3 of this
document replaces Section 2.4 of [RFC2595].
Note that this document doesn't apply to use of TLS in MTA-to-MTA
SMTP.
This document provides a consistent TLS server identity verification
procedure across multiple email-related protocols. This should make
it easier for Certification Authorities (CAs) and ISPs to deploy TLS
for email use and would enable email client developers to write more
secure code.
Melnikov Standards Track [Page 2]
RFC 7817 TLS Server Identity Check for Email March 2016
2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
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