[Linphone-developers] b256 SAS implementation for bzrtp

[Eli Burke]

Building on Ben Sartor’s excellent BZRTP patches to add support for the non-mandatory algorithms, here are patches to add the b256 SAS format. Instead of returning a 4 character SAS string like “7jb3” it will return two words such as “seabird:asteroid”. Per the RFC, the words come from the PGP Word List and should not be localized: http://en.wikipedia.org/w/index.php?title=PGP_word_list

oRTP and ms2 need small patches to extend the length of the SAS variable in the eventData structure. liblinphone was patched to add linphonerc overrides for each set of algorithms. No default values are changed from stock Linphone: Ben’s patch sets sensible ZRTP defaults based on the config setting for “srtp_crypto_suites”, this patch adds e.g:

zrtp_key_agreements_suites=MS_ZRTP_KEY_AGREEMENT_EC38

zrtp_cipher_suites=MS_ZRTP_CIPHER_AES3

zrtp_auth_suites=MS_ZRTP_AUTHTAG_HS80

zrtp_hash_suites=MS_ZRTP_HASH_S256

zrtp_sas_suites=MS_ZRTP_SAS_B256

Note that due to the nature of the ZRTP spec, the mandatory algorithms are always added and used during the initial ZRTP handshake, so it is not necessary to specify B32 to be backwards compatible with older clients. 

bzrtp_b256_patch.patch
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liblinphone_b256_patch.patch
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ms2_b256_patch.patch
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ortp_b256_patch.patch
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