From: "Florian Oelmaier" <[EMAIL PROTECTED]>
Subject: RE: cvs commit: openssl/ssl s3_lib.c ssl.h ssl_algs.cssl_ciph.cssl_locl.h 
tls1.h
Date: Thu, 8 Feb 2001 18:00:04 +0100
Message-ID: <[EMAIL PROTECTED]>

flo> > > Hmm, first of all, the responder (as I understood RFC 2560) should
flo> > > always send back the exact same nonce.  However, the client shouldn't
flo> > > go crashing, it should give back an error code of some kind.
flo> > >
flo> >
flo> > Yes I agree. I'll look into it.
flo> 
flo> I read the RFC very carefully. There is no sentence like "if the client
flo> sends a nonce-extension, the server SHALL reply to it". In fact point 4.4
flo> states:

Unfortunately, RFC 2560 is extremely badly written for an RFC (IMHO),
and there are many places where you have to sense the intention more
than read the wordings very carefully.  Now, tell me, if you look
intelligently at it, how do you bind the request and the response to
avoid replay attacks without requiring the exact same nonce to be
returned?  I ask you to think intelligently, not just to read the
exact wording here.

I had a discussion with other people last summer about the need to
do double hashing in some places, simply because the RFC left that
open for interpretation, or so it seemed.  The best way to find out
what is really intended, get in touch with the authors or with the
ietf-pkix list.  In any case, be polite, you'll be talking to some
very knowledged people.

flo> So any OCSP-responder not answering to OCSP-nonce is completly conforming
flo> with RFC2560. Therefore, openssl should give a warning, not an error.

Well, in that case, the whole nonce thing is completely useless,
because if it's optional, you won't avoid replay attacks.

flo> PS: The responder will go public this week. I´ll announce the
flo> IP-address here.

Cool.

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