Hi,

I'm using hashcash.el bundled with the Gnus distribution and the
hashcash v0.25 binary under the linux system.  I've modified
hashcash.el a bit since I got the following error.  Is it
reasonable or do I need any other requirement?

Signaling: (error "Unknown hashcash format version")
  (cond ((equal ... ?:) 1.2) ((equal ... ?:) 1.1) (t (error "Unknown hashcash format version")))
  hashcash-version("hashcash token: 0:030528:yamaoka@jpl.org:8bdd14129fd11df5")
  (number-to-string (hashcash-version pay))
  (insert-before-markers "X-Payment: hashcash " (number-to-string (hashcash-version pay)) " " pay "\n")
[...]
  hashcash-insert-payment("yamaoka@jpl.org")

I think we need to use the -q option to call the hashcash binary:

sh-2.05b$ hashcash -b 1 x|cat -
hashcash token: 0:030528:x:d657059d895c6292
0:030528:x:d657059d895c6292

sh-2.05b$ hashcash -q -b 1 x|cat -
0:030528:x:50c32261071a29c0

In addition, hashcash.el uses three cl run-time functions;
subseq, mapc, and caddr, though mapc is built-in in the recent
Emacs and cl provides a compiler macro for caddr.  I made a
complete patch to hashcash.el to meet Gnus' policy that it
should never use cl run-time functions and still supports Emacs
20.  How about it?