SPAM BUSTER! Part 4 of 4

Crytography – “zpv dbou tff nf!”

The most commonly use form of crytography used in Anti spam would probably be DomainKeys Indentify Mails (DKIM). Similary to SPF, DKIM is interested in indentifying the sender. But on top of that, DKIM also help in protecting the integrity of the mail content. DKIM does it by using a set of keys and by providing positive identification of the signer’s identity along with an encrypted “hash” of the message content allowing messages to be checked to verify that they are from purported senders (authentication) and have arrived unaltered (message integrity).
There are 3 main important keys in DKIM.
1) Digital Signature
2) Definittion of the field over which the digital signature was calculate
3) Sending Domain
The public key was published to the public Domain Name Server (DNS). When the receiver received the mail, it checked the DKIM signature against the sender’s public key through the DNS. If the incoming message cannot be verified then the receiving server knows it contains a spoofed address or has been tampered with or changed. A failed message can then be rejected, or it can be accepted but have it tagged according with “certainly spam”, “probably spam”, etc.

Email is an important form of communication in our lives and because of the heavy usage of email, spam are here to stay. Spam evolved quickily making it very difficult to stop them forever. Therefore we need different combination of anti spam technologies to put up an effective fight against spam. Hope this set of blogs would give you a better insight of anti spam technologies.

End of Part 4