Re: Hashcash

[Aaron Toponce]

On Thu, Mar 03, 2011 at 05:23:43PM -0700, Aaron Toponce wrote:
> So, has anyone successfully implemented Hashcash into Mutt, and if so, how?

Here is what I came up with. It's a Python script that runs as my default
editor. The script calls Vim, after which, it parses the headers and adds
the necessary tokens. I haven't found any bugs yet, but I'm sure I will
soon enough. I also blogged about it here:

http://pthree.org/2011/03/24/hashcash-and-mutt/

Now to start working on the verification process. I figure I can use
$display_filter for that, and just not filter anything, but execute another
Python script.

Anyway, thought I'd post an update.

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#!/usr/bin/env python

import csv
import fileinput
import rfc822
import subprocess
import sys

subprocess.call("vim %s" % sys.argv[1], shell=True)

file = open(sys.argv[1], 'r')
headers = rfc822.Message(file)

to_emails = headers.getaddrlist("To")
cc_emails = headers.getaddrlist("Cc")

email_addrs = []
tokens = []

# Harvest all email addresses from the header
for email in to_emails:
    email_addrs.append(email[1])

for email in cc_emails:
    email_addrs.append(email[1])

# Remove duplicate emails from the list, requires Python 2.5 and later
email_addrs = list(set(email_addrs))

# Check if an appropriate token is already generated for the mail
if headers.has_key("X-Hashcash"):
    for list in headers.getheaders("X-Hashcash"):
        email_addrs.remove(list.split(":")[3])
if headers.has_key("Hashcash"):
    for list in headers.getheaders("Hashcash"):
        email_addrs.remove(list.split(":")[3])

# Call the hashcash function from the operating system to mint tokens
for email in email_addrs:
    t = subprocess.Popen("hashcash -m %s -X -Z 2" % email, shell=True, stdout=subprocess.PIPE)
    tokens.append(t.stdout.read())

# Write the newly minted tokens to the header
f = fileinput.FileInput(sys.argv[1], inplace=1)
for line in f:
    line = line.strip()
    if f.lineno() == 1:
        for token in tokens:
            print token,
        print line
        continue
    else:
        print line

file.close()

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