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List:       voipsec
Subject:    Re: [VOIPSEC] Voipsec Digest, Vol 8, Issue 24
From:       Randell Jesup <rjesup () wgate ! com>
Date:       2005-08-31 18:14:42
Message-ID: ybur7ca3re5.fsf () jesup ! eng ! tvol ! net ! jesup ! eng ! tvol ! net
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"Chorley, Will" <Will_Chorley@labs.sbc.com> writes:
>I've been watching this thread on STRP and have a couple of questions.
>It has been suggested that you could put a key in the sdp and use TLS to
>encrypt.  My understanding is that TLS is essentially hop by hop and
>thus there is no guarantee that the security will be maintained from end
>to end (particularly across administrative domains) - if one hop is not
>encrypted you might as well send the whole thing in the clear!  So what
>proposals are there to ensure end to end security of the signaling path
>- or at least the SDP data without prior arrangement with the receiving
>party?

You can do all the other e2e security mechanisms on top of TLS, or without
it as you wish - MIKEY (or equivalent) with DH, S/MIME, RSA, etc.  Part of
the problem is that there are so many variants, and another part is that
many of them have preconditions or high cost (PKI, CPU power, distributing
and protecting shared secrets, etc).  And there's the problem of proxies
needing to rewrite the SDP (for border controllers, NATs, etc, plus
adding themselves to the SIP routing).

SIPS: addresses are supposed to only be routed to other SIP proxies via
TLS, thus maintaining the security level of the traffic - though the
security of the servers themselves is another thing, as mentioned, if
the message is decrypted at each hop.

-- 
Randell Jesup, Worldgate (developers of the Ojo videophone), ex-Amiga OS team
rjesup@wgate.com


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