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

State Posted
Posted Date 2014-11-21
From Group ITU-T-SG-16-Q3
From Contact Rosa De Vivero
To Group tls
To Contacts Sean Turner
Joseph Salowey
CcStephen Farrell
Kathleen Moriarty
Response Contact
Purpose For comment
Deadline 2015-02-01 Action Taken
Attachments LS on TLS and DTLS terminology [to 3GPPA SA3, IETF WG TLS, 3GPP CT4]
Liaisons referring to this one Response to LS on TLS and DTLS terminology [to 3GPPA SA3, IETF WG TLS, 3GPP CT4]
ITU-T Q3/16 works on support for the TLS and DTLS protocols in decomposed gateways using ITU-T H.248 as gateway control protocol. Initial support of these protocols is available, see published Recommendations ITU-T H.248.90 (10/2014) for TLS and ITU-T H.248.93 (10/2014) for DTLS. Initial support means that the (D)TLS protocols were modelled by so-called H.248 bearer connections (termed as "TLS bearer session" / "DTLS bearer session" in the Recommendations). These are abstractions, not necessarily equivalent to real (D)TLS sessions or (D)TLS connections, but sufficient for basic support by H.248 gateways.

However, additional support in the area of security and multiplexed protocol stacks ("WebRTC") imply a more precise model of TLS and DTLS protocol objects.

ITU-T Q3/16 would appreciate if you could provide clarifications particularly with respect to:

1.      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)
2.      the DTLS association concept, e.g., is it equivalent to a DTLS session or DTLS connection or something in addition?
3.      the TLS renegotiation procedure: what is the definition and at which level (TLS session or TLS connection level) does this procedure occur?
4.      the TLS resumption procedure: what is the definition and relation to TLS renegotiation?

The location of TLS or DTLS endpoints in terminal and gateway equipment is slightly different due to the decomposition approach of H.248 gateways and their internal, hierarchical model of H.248 terminations and H.248 stream endpoints. Support of (D)TLS procedures (beyond the pure establishment and release) demand for the unambiguous detection of events (such as the differentiation between TLS renegotiation and TLS resumption from TLS establishment). As part of the support of (D)TLS endpoints, the H.248 media gateways are able to determine the TLS profile and protocol capabilities via so called auditing capabilities procedures. However it is unclear which protocol capabilities are related to a (D)TLS session and (D)TLS connection and thus the MGC and MG may have different interpretations. The results of auditing TLS protocol capabilities and parameter values should be based on a common object model between the H.248 media gateway and its controller.

ITU-T Q3/16 is appreciative for your cooperation.