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Beat Spam Using Hashcash

Posted by timothy on from the variation-on-a-theme dept.

Shell writes "If they want to send spam, make them pay a price. Built on the widely available SHA-1 algorithm, hashcash is a clever system that requires a parameterizable amount of work on the part of a requester while staying "cheap" for an evaluator to check. In other words, the sender has to do real work to put something into your inbox. You can certainly use hashcash in preventing spam, but it has other applications as well, including keeping spam off of Wikis and speeding the work of distributed parallel applications." If you're specifically interested in hashcash for your mail server, Camram has some interesting ideas -- their Frequently Raised Objections page may be illuminating.

5 of 324 comments (clear)

  1. Hashcash got me arrested... by Anonymous Coward · · Score: 5, Funny

    Those damn police dogs can smell through plastic pretty well!

    1. Re:Hashcash got me arrested... by Infinityis · · Score: 5, Funny

      Maybe Winzip and Ziplock should merge. I think it'd be nice to have encrypted, password protected sandwich bags, but at 90% compression, I think the bread might not taste so good afterwards.

  2. Re: Slashdot Spam Form Response by er_col · · Score: 5, Insightful

    Thanks for the usual Spam Form Response. I think it is remarkable that very few choices are marked on it this time around. And if you read the Frequently Raised Objections page, you may well end up with no marks left at all. So this hashcash idea does sound really interesting.

  3. I had to quit smoking... by RandoX · · Score: 5, Funny

    ...because I was out of hash cash.

  4. Re:Greylisting worked for my company by Haegar · · Score: 5, Informative

    Tried it at work - stopped loads of spam, but had to disable it because out there are too many broken smtp servers (on short inspection mostly lotus notes) that think an return code of 4xx is a permanent error and bounce the mail.

    And my boss is not happy when even ONE important mail from a client is not reaching him.

    --
    c'ya haegar