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- Subject: Re: random, digest, uuid, cipher & Co
- From: David Haley <dchaley@...>
- Date: Wed, 13 Apr 2005 11:21:15 -0700
I would like to simulate a public key infrastructure on the cheap for
authentication purpose... for example, two applications communicate
over SMTP and the server would like to authenticate the client...
To validate a signature, the server call back the client with both the
original banner value as well as the signature it has received. The
client can then validate the signature by encrypting the value with
its private key and see if it matches.
If the client is in charge of validating the signature, where is your
authentication? Are you worried about connection interception? Your
protocol seems like it is very vulnerable to an intruder listening on
the network who could impose as either one of the players.
As the others have pointed out, there is more to a secure protocol than
throwing together lots of hashes and encryptions. You took out the
shared secret; do you know what role it plays? Why is it important? Does
your protocol allow client authentication to the server? What about
server authentication to the client? Do you care about either/both of
these? Cryptography is only a portion of the problems when it comes to
protocols. Even a protocol that uses (theoretically!) unbreakable
cryptography can be very vulnerable to imposture or authentication failure.
p.s. Hi everybody! :-) I've been lurking for a while. The comments on
this list have been very useful in furthering my understanding of how
things should be done in Lua (i.e. the "Lua Way".) Thank you to all and
especially to the developers of this very fine language.