RFC 8997

Deprecation of TLS 1.1 for Email Submission and Access

📅 published March 2021, from ietf

RFC 8997: Deprecation of TLS 1.1 for Email Submission and Access 💌

okay bestie, let's get into it 🫶 this one's from the IETF (Internet Engineering Task Force), and it's RFC 8997 🎀

Authors: L. Velvindron (cyberstorm.mu) and S. Farrell (Trinity College Dublin) 👑
Category: Standards Track ✨
Date: March 2021 🌸
Updates: RFC 8314 🦋
ISSN: 2070-1721

Abstract

okay so this spec updates the recommendation for using TLS (Transport Layer Security) to keep email private between a Mail User Agent (MUA) and a Mail Submission Server or Mail Access Server 🔐 it updates RFC 8314, and that's the whole vibe 💅

Status of This Memo

this is an Internet Standards Track document 🔥

it's a product of the IETF and it represents the consensus of the IETF community 🫶 it got public review and was approved for publication by the Internet Engineering Steering Group (IESG). if you want more on Internet Standards, check out Section 2 of RFC 7841 📚

for the current status, any errata, and how to send feedback, go to https://www.rfc-editor.org/info/rfc8997 🌈

Copyright Notice

this document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) as they stand on the publication date. please actually read these, because they spell out your rights and restrictions. any Code Components pulled out of this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions, and they come without warranty, as the Simplified BSD License describes 🧚

1.  Introduction
2.  Conventions Used in This Document
3.  Updates to RFC 8314
4.  IANA Considerations
5.  Security Considerations
6.  References
  6.1.  Normative References
  6.2.  Informative References
Acknowledgements
Authors' Addresses

1. Introduction ✨

okay so [RFC8314] says the minimum recommended version of TLS is version 1.1 🙈 but TLS 1.1 got deprecated in [RFC8996], so that recommendation is no longer valid 💀 this document updates [RFC8314] so the minimum TLS version is TLS 1.2 🔥

2. Conventions Used in This Document

the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" are interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they show up in all capitals, just like here 🎀 lowercase ones are just regular words, bestie 💅

3. Updates to RFC 8314 🦋

this section is basically a glow-up for [RFC8314]. here's each before and after, copied exactly 🫶

Section 4.1 heading, the version bump:

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

the SSL and TLS deprecation paragraph, obsessed with this one 😭:

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:

|  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.

then there's the part about how [RFC8314] Section 4.1 should be revised. the text should be revised from the following 📚

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 TLS 1.2.

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.

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 ✨

no IANA actions here, bestie. this document has none 🌸

5. Security Considerations 🔐

the whole point of this doc is to write down updated recommendations for using TLS with email services. those recommendations come from [RFC8996] 💜 and yes, this is a big deal for email privacy, so please don't skip it 😭

6. References 📚

6.1. Normative References

[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>.

[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:
           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>.

[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 want to thank Vittorio Bertola and Viktor Dukhovni for their feedback 💖

Authors' Addresses 🎀

Loganaden Velvindron
cyberstorm.mu
88 Avenue De Plevitz Roches Brunes
71259
Rose Hill
Mauritius

Phone: +230 59762817
Email: logan@cyberstorm.mu


Stephen Farrell
Trinity College Dublin
Dublin
2
Ireland

Phone: +353-1-896-2354
Email: stephen.farrell@cs.tcd.ie

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