[VOIPSEC] Cisco 7960 (Skinny) with Asterisk

[Mohammad Halawah]

Hi every one,

I am writing my master thesis regarding SRTP interoperability. I would 
like to know how the keys are exchanged (protocol, key-length*) 
between CCM (Cisco callmanager) and Cisco7960 (SCCP v.8 firmware ) to 
establish SRTP-ed call. Then to mimic this with Asterisk.

The only information I managed to get from Cisco web-site is:
"Key Manager in CCM derives symmetric “shared secret” (SS)
keys used by phones for encryption".

In case this keys are distributed through protected (TLS/VPN**) 
Sdescriptions, then the mession is easy.

Best regards,
Mohammad
* most likely it's 128-bit (as it was in 2004)
** most likely TLS.