Liaison statement
Response to LS on TLS and DTLS terminology [to 3GPPA SA3, IETF WG TLS, 3GPP CT4]

State Posted
Posted Date 2015-02-02
From Group tls
From Contact Sean Turner
To Group ITU-T-SG-16-Q3
To Contacts Rosa De Vivero
CcJoseph Salowey
Stephen Farrell
Kathleen Moriarty
Transport Layer Security Discussion List
Scott mansfield
Response Contact Christian Groves
Purpose In response
Attachments (None)
Liaisons referred by this one LS on TLS and DTLS terminology [to 3GPPA SA3, IETF WG TLS, 3GPP CT4]
Body
Thanks for your questions about (D)TLS.  What follows is a response to your
questions; questions proceeded by Q# and answers by A#.  If you have
additional question please let us know.

Q1.

[What is] the distinction between (D)TLS session and (D)TLS connection (which
implies a definition for each term, beyond the available descriptions /
glossary from RFC side)

A1.

A TLS session is shared cryptographic state established by a full TLS
handshake between two peers.  The session’s cryptographic state is used to
establish the cryptographic key material for a TLS connection.  A TLS
connection is a transport relationship established between two peers that
contains the cryptographic state to cryptographically protect data sent and
received on the connection established through a full or abbreviated (session
resumption) TLS handshake.  A TLS session may span one or more TLS
connections.  Every TLS connection is associated with one TLS session.  If
session resumption (abbreviated handshake) is not used then the TLS session
and TLS connection will essentially be the same.  A TLS session is identified
by a Session ID in the client and server hellos.  A TLS connection is usually
identified by a host addresses and port numbers.

Q2.

The DTLS association concept, e.g., is it equivalent to a DTLS session or DTLS
connection or something in addition?

A2.

The DTLS association is the same as a DTLS connection

Q3.

The TLS renegotiation procedure: what is the definition and at which level
(TLS session or TLS connection level) does this procedure occur?

Q4.

The TLS resumption procedure: what is the definition and relation to TLS
renegotiation?

A3 and A4:

Resumption refers to the use of the state from an existing TLS session to
establish a new TLS connection using an abbreviated handshake.  During
resumption the cryptographic parameters (algorithms etc.) remain the same. 
TLS renegotiation is the process of executing a new TLS handshake to establish
new cryptographic parameters for a TLS connection (effectively a new TLS
connection using the same host addresses and ports as the previous one). If
the handshake is a full handshake then both a new session and a new connection
are established and the renegotiated session may have different parameters.

Please note that session resumption and renegotiation are optional features;
though TLS 1.2 recommended support for renegotiation; renegotiation was also
updated by RFC 5746.  Please note that TLS 1.3 is currently under development
and these features are being reviewed.