Internet DRAFT - draft-ietf-uta-tls-for-email
draft-ietf-uta-tls-for-email
Network Working Group L. Velvindron
Internet-Draft cyberstorm.mu
Updates: 8314 (if approved) S. Farrell
Intended status: Standards Track Trinity College Dublin
Expires: September 25, 2020 March 24, 2020
Deprecation of use of TLS 1.1 for Email Submission and Access
draft-ietf-uta-tls-for-email-05
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.
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This Internet-Draft will expire on September 25, 2020.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
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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. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Informative References . . . . . . . . . . . . . . . . . 5
7.2. Normative References . . . . . . . . . . . . . . . . . . 5
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[I-D.ietf-tls-oldversions-deprecate], this recommendation is no
longer valid.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."
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NEW:
"As soon as practicable, MSPs currently supporting Secure Sockets
Layer (SSL) 2.x, SSL 3.0, TLS 1.0 or TLS 1.1 SHOULD transition their
users to TLS 1.2 or later and discontinue support for those earlier
versions of SSL and TLS."
In Section 4.1, the text should be revised from:
OLD:
One way is for the server to refuse a ClientHello message from any
client sending a ClientHello.version field corresponding to any
version of SSL or TLS 1.0.
NEW:
One way is for the server to refuse a ClientHello message from any
client sending a ClientHello.version field corresponding to any
version of SSL or TLS earlier than TLS1.2.
OLD:
"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. "
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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. "
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 1.1 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. Acknowledgement
The authors would like to thank Vittorio Bertola and Viktor Dukhovni
for their feedback.
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7. References
7.1. 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,
<https://www.rfc-editor.org/info/rfc4346>.
7.2. Normative References
[I-D.ietf-tls-oldversions-deprecate]
Moriarty, K. and S. Farrell, "Deprecating TLSv1.0 and
TLSv1.1", draft-ietf-tls-oldversions-deprecate-06 (work in
progress), January 2020.
[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/info/rfc2119>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>.
[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,
<https://www.rfc-editor.org/info/rfc8314>.
[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/info/rfc8446>.
Authors' Addresses
Loganaden Velvindron
cyberstorm.mu
88 Avenue De Plevitz Roches Brunes
Rose Hill 71259
Mauritius
Phone: +230 59762817
Email: logan@cyberstorm.mu
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Stephen Farrell
Trinity College Dublin
Dublin 2
Ireland
Phone: +353-1-896-2354
Email: stephen.farrell@cs.tcd.ie
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