Hi Werner, On 02/05/2013 08:17 AM, Werner Dittmann wrote: > PJSIP also supports a ZRTP implementation that negotiates the key data via > the media channel and provides a PJSIP transport for this. Already integrated > with SIP/SDP to insert optional SDP data. please correct me if I'm wrong: the key exchange protocols supported by ZRTP/ZORG are DH-based [1] thus the key-exchange occurs in a single round-trip as does SRTP. Furthermore a media session must be established before the key-exchange can occurred. Tim's Email from 1/31/2013 15:11 and previous one definitely shows that more than inserting optional data in the SDP will be necessary. Best Regards, Alain Totouom [1] http://www.zrtp.org/featurecplusplus > Am 05.02.2013 01:18, schrieb Alain Totouom: >> Hello Tim, >> >> On 02/04/2013 03:58 PM, McLeod, Tim wrote: >>> Attempting to use/modify pjsip user agent such that it uses SRTP. To obtain the key for the SRTP session it is necessary to negotiate with the remote endpoint. We think that a single message/response negotiation would be straightforward since we could simply rely on the call set-up messages. However, the negotiation we are required to use is a double message/response conversation, i.e.: >>> >>> I_MESSAGE1 >>> R_MESSAGE1 >>> I_MESSAGE2 >>> R_MESSAGE2 >>> >>> Has anyone any experience of using pjsip for this type of key/call negotiation? Unfortunately we are under extremely tight time constraints, literally just a couple of days to resolve this! >>> >> >> PJSIP already supports SRTP. >> The key exchange occurs in a single round-trip. >> If you need multiple round-trips for the key-exchange as your >> message implies, consider adapting and implementing something like >> RFC #4567. This is of course heavily RTSP-oriented, but you can >> still adapt that solution to fit into the SIP-Ecosystem. >> >> I can assist your Engineers and/or implement that for you in a fully >> SIP compliant manner using PJSIP. >> >> Best Regards, >> Alain Totouom >> >> >>> Tim McLeod MBCS CITP >>> Principal Engineer >>> Tel: +44 1633 715097 >>> Mob: +44 7765 088364 >>> Email: tim.mcleod at cassidian.com<mailto:tim.mcleod at cassidian.com> >>> RLI: tim.mcleod at eads.r.mil.uk<mailto:tim.mcleod at eads.r.mil.uk> >>> Website: www.cassidian.com<http://www.cassidian.com/> >> >> > > -- "" (o)(o) _____o00o__(__)__o00o_____ 1024D/A9F85A52 2000-01-18 Alain Totouom <totouom at gmx.de> PGP Fingerprint DA180DF2 FBD25F67 0656452D E3A27531 A9F85A52 3072D/146D10DE 2011-09-29 Alain Totouom <totouom at gmx.de> PGP Fingerprint 39A4F092 FFA7C746 CC305CB0 69091911 146D10DE
