[hashcash] Re: Hashcash and GPGPU

  • From: Adam Back <adam@xxxxxxxxxxxxxxx>
  • To: hashcash@xxxxxxxxxxxxx
  • Date: Sat, 16 Jun 2012 17:53:43 +0200

I think in principle it should be possible to reuse from the work done on
bitcoin because as Bas noted the bitcoin work function is hashcash.  (Yes
with a different string format, though that is not relevant, but with
SHA-256 rather than SHA1).  Still SHA-256 and SHA1 are rather similar in
design so to change the code from an opencl or cuda implementation should
not be that hard).

There also may well be direct GPU implementations of SHA1 available because
for example SHA1 is more commonly used in password systems than SHA-256 and
there are some GPU password cracking/testing tools around.

I'd be happy to integrate if anyone wants to try that.

I dont know about debian removing anything - didnt receive any comment to
that effect.  While there has not be recent code changes, there have also
not been any bug reports so why fix whats not broken ;) Note there are
actual users of hashcash in its mail application for example via spam
assassin which is quite widely used (on the server side).  So I think it
remains interesting to have support for hashcash on the client side.


On Sat, Jun 16, 2012 at 08:24:09AM -0600, Aaron Toponce wrote:
On Sat, Jun 16, 2012 at 04:07:31PM +0200, Bas Steendijk wrote:
On 2012-06-16 16:04, Aaron Toponce wrote:
>Has any work been done to mint tokes using GPUs? I recently purchased to


Not my best spelling, is it? :)

i know for a fact that it could be done - bitcoin is done on GPU and
it's the same kind of work (calculating hashes). so it has to be
implemented in the official implementation, otherwise spammers have
the advantage.

Yeah. Of course it's possible. I'm more or less just curious if it's
actually being worked on. Seems the project is dead, and Debian has
debated removing it from the repositories as a result [1], so I'm not
expecting much, but I thought I'd throw it out there.

   1. I'm sure I read this on the -devel list, but now I can't find it.

Right now, I'm only minting 20-bit tokens. It would be nice to mint 24-bit
or larger. :)

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