The Postmark-protocol is used to confirm the authenticity of an e-mail.
It does this by generating a hash from the title and recipient, using a
SHA-1 based algorithm, developed by Microsoft. This method would work
against spammers because, according to Microsoft:
"The authentication takes between the 10 and 20 seconds, and that's time
spammers don't have.".
In my opinion this would be a faulty statement. It's true spammers can't
spare such an amount of time, however relying on such an encryption
ends in fail by definition, since it's only a matter of time before even
the toughest encryptions go down in seconds. Although you could turn to
2048-bits RSA, at least a 8800 GT wouldn't get the job done.
And this is exactly what has happened here. Codreanu uses a GPU in
combination with nVidia's CUDA framework
. Which GPU, you ask? A Geforce
8800 GT, a cheap videocard available on the consumers market. He
succeeds in replicating five hashes per second. which bottles down to
432.000 hashes a day, of which 6% of the generated hashes are invalid.