

Decrypting SDES Protected SRTP Phone Calls - eloycoto
https://www.acritelli.com/hacking-voip-decrypting-sdes-protected-srtp-phone-calls/

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zaroth
What could possibly be the _point_ of putting a key field in the protocol? Why
have a key at all of you already entirely depend on a higher level wrapper
like TLS to protect it? It seems like the only purpose is increasing the
incidence of self-inflicted gunshot wounds to your feet. It's not security.
It's not even obscurity. It's just complexity!

The only thing I can think of is establishing the key over TLS so you can then
drop TLS later for devices that don't support it but continue the encrypted
session using a simpler bare cipher. If the goal is to strip away TLS
complexity, cipher suite negotiation, resumption, etc. functionality to just
have a basic fixed cipher, this sounds stupendously more complex than just
doing a DH key exchange in the first place, e.g. spiped.

~~~
Canada
Encrypting SIP doesn't protect the payload at all. The purpose of this
protocol is to remedy that.

ZRTP is a much better solution, as it negotiates keys in band and doesn't
depend on the confidentiality of the signalling channel.

~~~
zaroth
That makes sense. In the context of isolated control and data streams that
must be separately encrypted, they are saying 'put the data key here in the
signaling packet' but protecting the control plane is a separate exercise.

