How does distributed checksum works?

I am looking开发者_运维知识库 for information as to how distributed checksum applications like Vipul's razor, Pyzor or DCC works? I have a similar requirement where I can use such a distributed checksum feature in my program.

So I am looking for some documentation explaining the algorithms behind distributed checksums.

with regards,

raj

Pyzor is an implementation of "hash sharing". Quote from SpamAssassin's Wiki:

One of the approaches used to identify spam goes like this; if I see a spam message at 8:30 in the morning, I send a checksum of that message to an online database of spam. When you get that message a little later on in the morning, your mail system asks that online database, "Has anyone reported this as spam?". The online database can report back "yes", allowing your mail system to raise the spam score for that message.

Depending on what you're trying to do with distributed hashes, DHTs (Distributed hash tables) might also be interesting for you.