March 10, 2008 SIPPING WG IETF-71 1

Secure Media Recording and Transcoding with the Session

Initiation Protocol

draft-wing-sipping-srtp-key-03

Dan Wing <dwing@cisco.com>

Francois Audet <audet@nortel.com>

Steffen Fries <steffen.fries@siemens.com>

Hannes Tschofenig <Hannes.Tschofenig@nsn.com>

Alan Johnston <alan@sipstation.com>

Note: IPR disclosure by Avaya

March 10, 2008 SIPPING WG IETF-71 2

New Sections on Use Cases

• Recording Modes– Always On Recording– Recording On Demand– Required Recording– Pause and Resume Recording

• Recording Call Flows– Always On Recording– Recording On Demand– Required Recording– Pause and Resume Recording Call Flow– Conference Recording

March 10, 2008 SIPPING WG IETF-71 3

Changes• Recorder as a SIP UA instead of an invisible packet

sniffing device• A Controller as a B2BUA in the middle

– Similar to a Focus B2BUA which has been standardized by the IETF

– Only Role is to INVITE Recorder and copy media stream to recorder

• No mixing

– Avoids• Having only special UAs in recording scenarios• Double bandwidth problems at endpoint

• Doing recording in endpoint UA still OK, it just does not require as much standardization

March 10, 2008 SIPPING WG IETF-71 4

Alice Controller Bob Recorder | | | | | INVITE F1 | | | |--------------->| | | |(100 Trying) F2 | | | |<---------------| INVITE F3 | | | |--------------------------------->| | | | 200 OK F4 | | |<---------------------------------| | | | ACK F5 | | |--------------------------------->| | | INVITE F6 | | | |------------->| | | |180 Ringing F7| | | |<-------------| | | 180 Ringing F5 | | | |<---------------| 200 OK F6 | | | |<-------------| | | 200 OK F7 | | | |<---------------| | | | ACK F8 | | | |--------------->| ACK F9 | | | |------------->| | | | INVITE F10 | | | |--------------------------------->| | | | 200 OK F11 | | |<---------------------------------| | | | ACK F12 | | |--------------------------------->| | Both way SRTP Established | | |<==============>|<============>| | | | SRTP From Alice | | |=================================>| | | SRTP From Bob | | |=================================>|

Figure 1: Controller Proxy or B2BUA

March 10, 2008 SIPPING WG IETF-71 5

Alice Focus/Mixer Bob Recorder | | | | | | SUBSCRIBE F1 | | |<---------------------------------| | | | 200 OK F2 | | |--------------------------------->| | | NOTIFY F3 | | | |--------------------------------->| | | | 200 OK F4 | | |<---------------------------------| | INVITE F5 | | | |--------------->| | | | 200 OK F6 | | | |<---------------| | | | ACK F7 | | | |--------------->| | | | SRTP | NOTIFY F8 | | |<==============>|--------------------------------->| | | | 200 OK F9 | | |<---------------------------------| | | INVITE F10 | | | |<-------------| | | |180 Ringing F11 | | |------------->| | | | 200 OK F12 | | | |------------->| | | | SRTP | | | |<============>| | | | NOTIFY F13 | | | |--------------------------------->| | | | 200 OK F14 | | |<---------------------------------| | | INVITE Join: A-B F15 | | |<---------------------------------| | | | 200 OK F16 | | |--------------------------------->| | | | ACK F17 | | |<---------------------------------| | | Mixed SRTP from Alice and Bob | | |=================================>|

Figure 4: Conference Recording Call Flow

March 10, 2008 SIPPING WG IETF-71 6

No Changes To

• Key disclosure mechanism– UA must cooperate and publish the key to

the recorder– Some sort of disclosure like ZRTP

• Event package– Still needs work

March 10, 2008 SIPPING WG IETF-71 7

Conclusion

• Is the working group interested in working on– SIP call recording call flows?– Requirements?– Mechanisms?