1. draft-wing-avt-dtls-srtp-key-transport-01
MSEC Working Group
draft-wing-avt-dtls-srtp-key-transport-01
Dan Wing,
IETF71, Philadelphia, March 2008
draft-wing-avt-dtls-srtp-key-transport-01

2. draft-wing-avt-dtls-srtp-key-transport-01
Overview
IETF68 (Prague), RTPSEC BoF selected DTLS-SRTP as the preferred SRTP keying mechanism
Only unicast, point-to-point was in scope
DTLS-SRTP Key Transport allows efficient SRTP operation for
Several unicast conferencing scenarios
Multicast
IETF71, Philadelphia, March 2008
draft-wing-avt-dtls-srtp-key-transport-01

3. Why Consider DTLS-SRTP for Multicast?
DTLS-SRTP works for group of 2
GDOI-SRTP is overkill for a group of 3
Useful for a larger group
DTLS-SRTP-Key-Transport allows optimizing SRTP keying for ‘small groups’
IETF71, Philadelphia, March 2008
draft-wing-avt-dtls-srtp-key-transport-01

4. Operation of DTLS-SRTP Key Transport for Multicast
IETF71, Philadelphia, March 2008
draft-wing-avt-dtls-srtp-key-transport-01

5. DTLS-SRTP-Key-Transport
DTLS-SRTP-Key-Transport is negotiated during TLS handshake
DTLS-SRTP session stays up for duration of call
SRTP key is sent within the DTLS session itself
As a new TLS content-type
IETF71, Philadelphia, March 2008
draft-wing-avt-dtls-srtp-key-transport-01

6. DTLS session with each listener
Each listener establishes unicast DTLS-SRTP session with speaker
Speaker uses DTLS-SRTP Key Transport to tell every listener the same SRTP key
Listener 1
speaker
Listener 2
Listener 3
DTLS-SRTP, transport speaker’s SRTP key “A”
IETF71, Philadelphia, March 2008
draft-wing-avt-dtls-srtp-key-transport-01

7. draft-wing-avt-dtls-srtp-key-transport-01
SRTP multicasting
SRTP packets are then multicasted to listeners
Listener 1
SRTP packet, key “A”
speaker
Listener 2
Listener 3
IETF71, Philadelphia, March 2008
draft-wing-avt-dtls-srtp-key-transport-01

8. DTLS-SRTP-Key-Transport
DTLS-SRTP-Key-Transport is negotiated during TLS handshake
DTLS-SRTP session stays up for duration of call
SRTP key is sent within the DTLS session itself
As a new TLS content-type
IETF71, Philadelphia, March 2008
draft-wing-avt-dtls-srtp-key-transport-01

9. draft-wing-avt-dtls-srtp-key-transport-01
Questions
draft-wing-avt-dtls-srtp-key-transport-01
Dan Wing,
IETF71, Philadelphia, March 2008
draft-wing-avt-dtls-srtp-key-transport-01