[16068] in cryptography@c2.net mail archive
"Approximate" hashes
daemon@ATHENA.MIT.EDU (Marcel Popescu)
Wed Sep 1 12:53:56 2004
X-Original-To: cryptography@metzdowd.com
X-Original-To: cryptography@metzdowd.com
From: "Marcel Popescu" <Marcel_Popescu@microbilt.com>
To: <cryptography@metzdowd.com>
Date: Wed, 1 Sep 2004 17:55:59 +0300
X-MDaemon-Deliver-To: cryptography@metzdowd.com
I am trying to build a Windows anti-spam thingy; it's supposed to "sit" in
between the mail client and the outer world, and indicate through mail
headers whether the incoming mail has a valid hashcash
http://www.hashcash.org/ "coin" (and, of course, to automatically add
hashcash to outgoing emails).
My problem is that I don't know what happens with the email in transit
(this, I believe, is an observation in the hashcash FAQ). I am worried that
some mail server might dislike ASCII characters with the high bit set, or
that a client uses some encoding which for some reason doesn't make it to
the destination unchanged.
Hence my question: is there some "approximate" hash function (which I could
use instead of SHA-1) which can verify that a text hashes "very close" to a
value? So that if I change, say, tabs into spaces, I won't get exactly the
same value, but I would get a "good enough"?
I don't know if this is possible. But if it is, I though this would be a
good place to find out about it.
Thanks,
Marcel
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