IETF-96 Proceedings

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Transport Layer Security (tls) (WG)

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Security Area Area Director(s):

Assigned Area Director

Technical Advisor(s)

Status Update (provided 2016-07-20)

The TLS working group met on Tuesday morning. We are continuing progress on TLS 1.3. Main discussion points included a change in the cipher suite model from a monolithic ID approach to a menu based approach. During the Hackathon on Saturday we had 7 different TLS 1.3 implementations achieve interoperability to various degrees. We expect to have a draft (probably -16) that "freezes" the wire format at the end of next month available for broad review by the cryptographic and security modeling communities. We plan on holding working group last call before the next IETF.  


Meeting Slides:

Blue Sheets:


Request for Comments:

Charter (as of 2015-10-14):

The TLS (Transport Layer Security) working group was
established in 1996 to standardize a 'transport layer'
security protocol. The basis for the work was SSL
(Secure Socket Layer) v3.0 [RFC6101]. The TLS
working group has completed a series of specifications
that describe the TLS protocol v1.0 [RFC2246],
v1.1 [RFC4346], and v1.2 [RFC5346] and DTLS
(Datagram TLS) v1.0 [RFC4347], v1.2 [RFC6347]
as well as extensions to the protocols and ciphersuites.

The primary purpose of the working group is to develop
(D)TLS v1.3. Some of the main design goals are as follows,
in no particular order:

o Develop a mode that encrypts as much of the handshake as
is possible to reduce the amount of observable data to
both passive and active attackers.

o Develop modes to reduce handshake latency, which primarily
support HTTP-based applications, aiming for one roundtrip
for a full handshake and one or zero roundtrip for repeated
handshakes. The aim is also to maintain current security

o Update record payload protection cryptographic
mechanisms and algorithms to address known weaknesses
in the CBC block cipher modes and to replace RC4.

o Reevaluate handshake contents, e.g.,: Is time needed in
client hello? Should signature in server key exchange
cover entire handshake? Are bigger randoms required?
Should there be distinct cipher list for each version? Are
additional mechanisms needed to prevent version rollback

o The WG will consider the privacy implications of
TLS1.3 and where possible (balancing with other requirements)
will aim to make TLS1.3 more privacy-friendly, e.g. via more
consistent application traffic padding, more considered use
of long term identifying values, etc.

A secondary purpose is to maintain previous version of
the (D)TLS protocols as well as to specify the use of
(D)TLS, recommendations for use of (D)TLS, extensions to
(D)TLS, and cipher suites. However, changes or additions
to older versions of (D)TLS whether via extensions or
ciphersuites are discouraged and require significant
justification to be taken on as work items.

With these objectives in mind, the TLS WG will also place a priority
in minimizing gratuitous changes to TLS.