> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Marcel Popescu > Sent: Wednesday, September 01, 2004 9:56 AM > To: [EMAIL PROTECTED] > Subject: "Approximate" hashes > > 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.
nilsimsa Computes nilsimsa codes of messages and compares the codes and finds clusters of similar messages so as to trash spam. What's a nilsimsa code? A nilsimsa code is something like a hash, but unlike hashes, a small change in the message results in a small change in the nilsimsa code. http://lexx.shinn.net/cmeclax/nilsimsa.html -- Keith Ray <[EMAIL PROTECTED]> -- OpenPGP Key: 0x79269A12 --------------------------------------------------------------------- The Cryptography Mailing List Unsubscribe by sending "unsubscribe cryptography" to [EMAIL PROTECTED]