draft-ietf-uta-tls-for-email-05.txt   rfc8997.txt 
Network Working Group L. Velvindron Internet Engineering Task Force (IETF) L. Velvindron
Internet-Draft cyberstorm.mu Request for Comments: 8997 cyberstorm.mu
Updates: 8314 (if approved) S. Farrell Updates: 8314 S. Farrell
Intended status: Standards Track Trinity College Dublin Category: Standards Track Trinity College Dublin
Expires: September 25, 2020 March 24, 2020 ISSN: 2070-1721 March 2021
Deprecation of use of TLS 1.1 for Email Submission and Access Deprecation of TLS 1.1 for Email Submission and Access
draft-ietf-uta-tls-for-email-05
Abstract Abstract
This specification updates current recommendation for the use of This specification updates the current recommendation for the use of
Transport Layer Security (TLS) protocol to provide confidentiality of the Transport Layer Security (TLS) protocol to provide
email between a Mail User Agent (MUA) and a Mail Submission Server or confidentiality of email between a Mail User Agent (MUA) and a Mail
Mail Access Server. This document updates RFC8314. Submission Server or Mail Access Server. This document updates RFC
8314.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This is an Internet Standards Track document.
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
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Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on September 25, 2020. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8997.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction
2. Conventions Used in This Document . . . . . . . . . . . . . . 2 2. Conventions Used in This Document
3. Updates to RFC8314 . . . . . . . . . . . . . . . . . . . . . 2 3. Updates to RFC 8314
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 4. IANA Considerations
5. Security Considerations . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations
6. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 4 6. References
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 6.1. Normative References
7.1. Informative References . . . . . . . . . . . . . . . . . 5 6.2. Informative References
7.2. Normative References . . . . . . . . . . . . . . . . . . 5 Acknowledgements
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses
1. Introduction 1. Introduction
[RFC8314] defines the minimum recommended version for TLS as version [RFC8314] defines the minimum recommended version of TLS as version
1.1. Due to the deprecation of TLS 1.1 in 1.1. Due to the deprecation of TLS 1.1 in [RFC8996], this
[I-D.ietf-tls-oldversions-deprecate], this recommendation is no recommendation is no longer valid. Therefore, this document updates
longer valid. Therefore this document updates [RFC8314] so that the [RFC8314] so that the minimum version for TLS is TLS 1.2.
minimum version for TLS is TLS 1.2.
2. Conventions Used in This Document 2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in [RFC2119] when they "OPTIONAL" in this document are to be interpreted as described in
appear in ALL CAPS. These words may also appear in this document in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
lower case as plain English words, absent their normative meanings. capitals, as shown here.
3. Updates to RFC8314 3. Updates to RFC 8314
OLD: OLD:
"4.1. Deprecation of Services Using Cleartext and TLS Versions Less | 4.1. Deprecation of Services Using Cleartext and TLS Versions
Than 1.1" | Less Than 1.1
NEW: NEW:
"4.1. Deprecation of Services Using Cleartext and TLS Versions Less | 4.1. Deprecation of Services Using Cleartext and TLS Versions
Than 1.2" | Less Than 1.2
OLD: OLD:
"As soon as practicable, MSPs currently supporting Secure Sockets | 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 | Layer (SSL) 2.x, SSL 3.0, or TLS 1.0 SHOULD transition their users
TLS 1.1 or later and discontinue support for those earlier versions | to TLS 1.1 or later and discontinue support for those earlier
of SSL and TLS." | versions of SSL and TLS.
NEW: NEW:
"As soon as practicable, MSPs currently supporting Secure Sockets | 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 | Layer (SSL) 2.x, SSL 3.0, TLS 1.0, or TLS 1.1 SHOULD transition
users to TLS 1.2 or later and discontinue support for those earlier | their users to TLS 1.2 or later and discontinue support for those
versions of SSL and TLS." | earlier versions of SSL and TLS.
In Section 4.1, the text should be revised from: In Section 4.1 of [RFC8314], the text should be revised from:
OLD: OLD:
One way is for the server to refuse a ClientHello message from any | One way is for the server to refuse a ClientHello message from any
client sending a ClientHello.version field corresponding to any | client sending a ClientHello.version field corresponding to any
version of SSL or TLS 1.0. | version of SSL or TLS 1.0.
NEW: NEW:
One way is for the server to refuse a ClientHello message from any | One way is for the server to refuse a ClientHello message from any
client sending a ClientHello.version field corresponding to any | client sending a ClientHello.version field corresponding to any
version of SSL or TLS earlier than TLS1.2. | version of SSL or TLS earlier than TLS 1.2.
OLD: OLD:
"It is RECOMMENDED that new users be required to use TLS version 1.1 | It is RECOMMENDED that new users be required to use TLS version
or greater from the start. However, an MSP may find it necessary to | 1.1 or greater from the start. However, an MSP may find it
make exceptions to accommodate some legacy systems that support only | necessary to make exceptions to accommodate some legacy systems
earlier versions of TLS or only cleartext." | that support only earlier versions of TLS or only cleartext.
NEW: NEW:
"It is RECOMMENDED that new users be required to use TLS version 1.2 | It is RECOMMENDED that new users be required to use TLS version
or greater from the start. However, an MSP may find it necessary to | 1.2 or greater from the start. However, an MSP may find it
make exceptions to accommodate some legacy systems that support only | necessary to make exceptions to accommodate some legacy systems
earlier versions of TLS or only cleartext." | that support only earlier versions of TLS or only cleartext.
OLD: OLD:
" If, however, an MUA provides such an indication, it MUST NOT | If, however, an MUA provides such an indication, it MUST NOT
indicate confidentiality for any connection that does not at least | indicate confidentiality for any connection that does not at least
use TLS 1.1 with certificate verification and also meet the minimum | use TLS 1.1 with certificate verification and also meet the
confidentiality requirements associated with that account. " | minimum confidentiality requirements associated with that account.
NEW: NEW:
" If, however, an MUA provides such an indication, it MUST NOT | If, however, an MUA provides such an indication, it MUST NOT
indicate confidentiality for any connection that does not at least | indicate confidentiality for any connection that does not at least
use TLS 1.2 with certificate verification and also meet the minimum | use TLS 1.2 with certificate verification and also meet the
confidentiality requirements associated with that account. " | minimum confidentiality requirements associated with that account.
OLD OLD
" MUAs MUST implement TLS 1.2 [RFC5246] or later. Earlier TLS and | 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 | SSL versions MAY also be supported, so long as the MUA requires at
least TLS 1.1 [RFC4346] when accessing accounts that are configured | least TLS 1.1 [RFC4346] when accessing accounts that are
to impose minimum confidentiality requirements. " | configured to impose minimum confidentiality requirements.
NEW: NEW:
" MUAs MUST implement TLS 1.2 [RFC5246] or later e.g TLS 1.3 | 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 | [RFC8446]. Earlier TLS and SSL versions MAY also be supported, so
long as the MUA requires at least TLS 1.2 [RFC5246] when accessing | long as the MUA requires at least TLS 1.2 [RFC5246] when accessing
accounts that are configured to impose minimum confidentiality | accounts that are configured to impose minimum confidentiality
requirements. " | requirements.
OLD: OLD:
" The default minimum expected level of confidentiality for all new | The default minimum expected level of confidentiality for all new
accounts MUST require successful validation of the server's | accounts MUST require successful validation of the server's
certificate and SHOULD require negotiation of TLS version 1.1 or | certificate and SHOULD require negotiation of TLS version 1.1 or
greater. (Future revisions to this specification may raise these | greater. (Future revisions to this specification may raise these
requirements or impose additional requirements to address newly | requirements or impose additional requirements to address newly
discovered weaknesses in protocols or cryptographic algorithms. " | discovered weaknesses in protocols or cryptographic algorithms.)
NEW: NEW:
" The default minimum expected level of confidentiality for all new | The default minimum expected level of confidentiality for all new
accounts MUST require successful validation of the server's | accounts MUST require successful validation of the server's
certificate and SHOULD require negotiation of TLS version 1.2 or | certificate and SHOULD require negotiation of TLS version 1.2 or
greater. (Future revisions to this specification may raise these | greater. (Future revisions to this specification may raise these
requirements or impose additional requirements to address newly | requirements or impose additional requirements to address newly
discovered weaknesses in protocols or cryptographic algorithms. " | discovered weaknesses in protocols or cryptographic algorithms.)
4. IANA Considerations 4. IANA Considerations
None of the proposed measures have an impact on IANA. This document has no IANA actions.
5. Security Considerations 5. Security Considerations
The purpose of this document is to document updated recommendations The purpose of this document is to document updated recommendations
for using TLS with Email services. Those recommendations are based for using TLS with email services. Those recommendations are based
on [I-D.ietf-tls-oldversions-deprecate]. on [RFC8996].
6. Acknowledgement
The authors would like to thank Vittorio Bertola and Viktor Dukhovni
for their feedback.
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 6. References
[I-D.ietf-tls-oldversions-deprecate] 6.1. Normative References
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 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, (TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008, DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>. <https://www.rfc-editor.org/info/rfc5246>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8314] Moore, K. and C. Newman, "Cleartext Considered Obsolete: [RFC8314] Moore, K. and C. Newman, "Cleartext Considered Obsolete:
Use of Transport Layer Security (TLS) for Email Submission Use of Transport Layer Security (TLS) for Email Submission
and Access", RFC 8314, DOI 10.17487/RFC8314, January 2018, and Access", RFC 8314, DOI 10.17487/RFC8314, January 2018,
<https://www.rfc-editor.org/info/rfc8314>. <https://www.rfc-editor.org/info/rfc8314>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>. <https://www.rfc-editor.org/info/rfc8446>.
[RFC8996] Moriarty, K. and S. Farrell, "Deprecating TLS 1.0 and TLS
1.1", RFC 8996, DOI 10.17487/RFC8996, March 2021,
<https://www.rfc-editor.org/info/rfc8996>.
6.2. 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>.
Acknowledgements
The authors would like to thank Vittorio Bertola and Viktor Dukhovni
for their feedback.
Authors' Addresses Authors' Addresses
Loganaden Velvindron Loganaden Velvindron
cyberstorm.mu cyberstorm.mu
88 Avenue De Plevitz Roches Brunes 88 Avenue De Plevitz Roches Brunes
Rose Hill 71259 71259
Rose Hill
Mauritius Mauritius
Phone: +230 59762817 Phone: +230 59762817
Email: logan@cyberstorm.mu Email: logan@cyberstorm.mu
Stephen Farrell Stephen Farrell
Trinity College Dublin Trinity College Dublin
Dublin 2 Dublin
2
Ireland Ireland
Phone: +353-1-896-2354 Phone: +353-1-896-2354
Email: stephen.farrell@cs.tcd.ie Email: stephen.farrell@cs.tcd.ie
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