BZRTP

What's BZRTP

BZRTP is an opensource implementation of ZRTP keys exchange protocol. The library written in C 89 is fully portable and can be executed on many platforms including both ARM processor and x86.

Licensing: The source code is licensed under GPLv3.

License

BZRTP library is dual-licensed and can be distributed either under a GNU GPLv3 license (open source, see LICENSE.txt) or under a proprietary license (closed source).

Copyright © Belledonne Communications SARL Johan Pascal is the original author of BZRTP.

Compatibility with RFC6189 - ZRTP: Media Path Key Agreement for Unicast Secure RTP

Mandatory but NOT implemented

• Sas Relay mechanism (section 7.3)
• Error message generation, emission or reception(which doesn't imply any security problem, they are mostly for debug purpose)

Optional and implementd

• multistream mode
• cacheless implementation
• zrtp-hash attribute in SDP

Optional and NOT implemented

• Go Clear/Clear ACK messages
• SAS signing

Supported Algorithms

• Hash : SHA-256, SHA-384
• Cipher : AES-128, AES-256
• SAS rendering: B32, B256(PGP word list)
• Auth Tag : HS32, HS80
• Key Agreement : DH-2048, DH-3072, X25519, X448

Note: X25519 and X448 Key agreements(RFC7748) are not part of RFC6189 and supported only when bctoolbox[1] is linking libdecaf[2]

Dependencies

• bctoolbox[1]: portability layer and crypto function abstraction

Build BZRTP

cmake . -DCMAKE_INSTALL_PREFIX=<prefix> -DCMAKE_PREFIX_PATH=<search_paths>

make
make install

Build options

• CMAKE_INSTALL_PREFIX=<string> : install prefix
• CMAKE_PREFIX_PATH=<string> : column-separated list of prefixes where to search for dependencies
• ENABLE_SHARED=NO : do not build the shared library
• ENABLE_STATIC=NO : do not build the static library
• ENABLE_STRICT=NO : build without the strict compilation flags
• ENABLE_TESTS=YES : build non-regression tests

Notes for packagers

Our CMake scripts may automatically add some paths into research paths of generated binaries. To ensure that the installed binaries are striped of any rpath, use -DCMAKE_SKIP_INSTALL_RPATH=ON while you invoke cmake.

Rpm packaging bzrtp can be generated with cmake3 using the following command: mkdir WORK cd WORK cmake3 ../ make package_source rpmbuild -ta --clean --rmsource --rmspec bzrtp--.tar.gz

• [1] git://git.linphone.org/bctoolbox.git or http://www.linphone.org/releases/sources/bctoolbox
• [2] https://sourceforge.net/projects/ed448goldilocks/