Hi Klaus, this is part of the ZRTP core implementation. The application only provides where to stores the data (filename). Regards, Werner Am 23.11.2010 20:06, schrieb Klaus Darilion: > Hi Werner! > > Thanks for taking this up. > > AFAIK ZRTP requires to persistently store some data (e.g. for key > continuity ...). Where will this be done? Automatically inside > transport_zrtp or is it the application's task to store these date? > > regards > Klaus > > Am 21.11.2010 11:07, schrieb Werner Dittmann: >> Dear all, >> >> some members of this mailing list pointed me to the enhancement >> request to >> implement ZRTP into the pjproject libraries. I browsed through the pj >> sources and would like to make the following proposal to implement ZRTP >> for pj. The follwing figure depicts at a high level the planned >> implementation: >> >> +-----------+ >> | | >> | SRTP-ZRTP | >> | | >> +-----------+ >> |C Wrapper | >> +-----+-----+ >> | >> | uses >> | >> +----------------+ +-------+--------+ +-+-----------------+ >> | App (pjsua) | | | |C| | >> | creates a | uses | transport_zrtp | uses | | GNU ZRTP | >> | ZRTP transport +------+ implements +------+W| core | >> | and implements | | ZrtpCallback | |r| implementation | >> |ZrtpUserCallback| | | |a| (ZRtp et al) | >> +----------------+ +----------------+ |p| | >> +-+-----------------+ >> >> Description: >> >> GNU ZRTP >> GNU ZRTP is the existing ZRTP implementation that handles the ZRTP >> protocol, performs necessary ZRTP computations, maintains some data in a >> file etc. I implemented this part in C++ (it's stable, tested to work >> with >> Phil Zimmermann's implementation) and it's licencse is GPL v3. >> Currently I >> implemented a first version of a C Wrapper to make GNU ZRTP accessible to >> C implementations. The C Wrapper covers the main functions already and >> will >> be enhanced during the pj project implementation. GNU ZRTP is a library, >> no requirement to have it as third party source in pjproject - it's >> already >> available as part of the GNU ccRTP project. >> >> >> transport_zrtp >> This is a new pjmedia transport that links into the transport stream, >> similar to the current SRTP transport. Thus transport acts as a filter >> that >> controls the flow of ZRTP, RTP, and SRTP data. This is obviously a new >> module. IMHO it should live in the pjmedia source, parallel to the other >> transport modules. This module will be the main development during the >> planned ZRTP integration. >> >> >> SRTP-ZRTP >> Instead of using the existing SRTP implementation I plan to use an own >> SRTP >> implementation (also a C++ implementation that has a C Wrapper). Some >> reasons why: the current libsrtp does not support AES 256 which is >> implemented >> for ZRTP. In addition ZRTP defines some more modern authentiation >> mechanisms >> in SRTP that I will implement step by step. In addition the ZRTP/SRTP >> module >> uses either openSSL or libgcrpyt as crypto backends, thus no own >> implementation >> of the AES cipher or bignum but reusing proven an well tested >> implementations. >> This module would live in an apporpriate third party directory. >> >> >> The callback stuff is implemented as usual. GNU ZRTP requires some >> external >> support functions, for example to send data via RTP, get a mutex, etc. >> Because >> these functions are system dependent the transport_zrtp module >> implements these >> and provides them via callback to GNU ZRTP. transport_zrtp uses >> UserCallback >> methods to inform the application about status changes, for example if >> security >> was established, which cipher was engaded, and some other user >> interactions. >> >> To implement this stuff I obviously need some help from pjproject >> gurus, in >> particular with the build and configuration stuff and the intrinsics >> of the >> transport mechanisms. I would start to evaluate the transport_srtp and >> the >> transport example to lower the learning curve. However, some support >> would >> highly appreciated once I had a first rough draft of the >> transport_zrtp code. >> >> >> Best regards, >> Werner >> >> _______________________________________________ >> Visit our blog: http://blog.pjsip.org >> >> pjsip mailing list >> pjsip at lists.pjsip.org >> http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org >
