It seems like the pre-master secret generated during the SRP protocol would make a good source to generate a shared private key using a secure hash to compress it down into a 128/256 symmetric key. The random values that get hashed into it seem to make it good for that purpose.
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$\begingroup$ I recommend that you state the question you want answered in the body of the question. $\endgroup$– D.W.Jun 18, 2014 at 1:04
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2 Answers
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From the RFC:
SRP also supplies a shared secret at the end of the authentication sequence that can be used to generate encryption keys.
It seems from my quick look over the RFC that that shared secret is the premaster secret, so you are correct.
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$\begingroup$ Ack! I even remember reading that now. I think i was wondering if it was uniform enough, or if I needed to HMAC it to death to be sure. $\endgroup$ Apr 4, 2012 at 0:29
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There is an explicit RCF 5054 which uses SRP to negotiate a shared key for a TLS connection. There are also hooks for OpenSSL to be able to use SRP to setup an SSL connection without using certificates using the SRP generated shared session key.
