Changes/GnuTLS-TLS1.3

GnuTLS enables TLS 1.3 by default

Summary

This change enables TLS 1.3 (draft28) support on the gnutls crypto library.

Owner

• Name: Nikos Mavrogiannopoulos
• Email: <your email address so we can contact you, invite you to meetings, etc.>
• Release notes owner:

Current status

• Targeted release: Fedora 29
• Last updated: 2018-07-18
• Tracker bug: <will be assigned by the Wrangler>

Detailed Description

This change will enable the TLS 1.3 protocol (draft28) on the gnutls library. TLS 1.3 is the latest version of the TLS protocol which addresses few shortcomings of the previous versions. The protocol has already been approved by IETF and is on its final publication stage, with only minor editorial changes expected. The change for gnutls depending is transparent to existing applications.

More information for applications using gnutls:

* https://nikmav.blogspot.com/2018/05/gnutls-and-tls-13.html

Note that due to crypto-policies being in effect this change only applies to applications which do not follow the crypto policy.

Benefit to Fedora

* This brings the latest TLS protocol support to applications depending on gnutls, when crypto policies are updated for TLS1.3.

Scope

• Proposal owners:

• Other developers: N/A (not a System Wide Change)

• Release engineering: [1]
  • List of deliverables: N/A (not a System Wide Change)

• Policies and guidelines: N/A (not a System Wide Change)

• Trademark approval: N/A (not needed for this Change)

Upgrade/compatibility impact

That change should have no impact on upgrade or compatibility. The TLS 1.3 protocol is designed in a way that does not cause incompatibility issues with existing (and even broken) implementations.

N/A (not a System Wide Change)

How To Test

* Existing work-flows which include secure communications should be tested
* Command line applications which use TLS (e.g., wget, lftp), should be tested against web-sites using TLS 1.3 (e.g., www.google.com)

N/A (not a System Wide Change)

User Experience

That change should not be noticeable by users except for applications which report the connected protocol. Other things users will notice

- Latency on TLS sessions will be reduced
- Performance of establishment of TLS sessions will be improved due to ed25519/x25519 support
- Privacy of TLS sessions will be improved from the perspective of passive eavesdroppers; no client certificate will be sent in the clear
- Transparent rekey of long-running sessions

Dependencies

GNOME, samba, rsyslog, wget, lftp, ...

Contingency Plan

If the expected transparent addition of TLS 1.3 cannot be assured (e.g., important issues are reported), the enablement of TLS1.3 protocol will be postponed for the next fedora release.

• Contingency mechanism: The gnutls maintainer will not enable TLS1.3 by default in the build
• Contingency deadline: Fedora 29 beta
• Blocks release? No; the contingency plan is sufficient and can avoid a release block

Documentation

* https://nikmav.blogspot.com/2018/05/gnutls-and-tls-13.html
* https://www.gnutls.org/manual/gnutls.html#Upgrading-from-previous-versions