From 1b88b67544eb59fa1c072d4db043dead7164cd5c Mon Sep 17 00:00:00 2001
From: Seth Schoen <schoen@eff.org>
Date: Mon, 16 Jul 2012 19:25:27 -0700
Subject: [PATCH] use C language hashcash program to generate cash from client

---
 client-webserver/client.py   | 10 ++++------
 client-webserver/hashcash.py |  1 -
 server-ca/chocolate.py       |  2 +-
 3 files changed, 5 insertions(+), 8 deletions(-)
 delete mode 120000 client-webserver/hashcash.py

diff --git a/client-webserver/client.py b/client-webserver/client.py
index 631ac1ce0..2e9c21191 100755
--- a/client-webserver/client.py
+++ b/client-webserver/client.py
@@ -2,15 +2,11 @@
 
 from chocolate_protocol_pb2 import chocolatemessage
 import M2Crypto
-import urllib2, os, sys, time, random, sys, hashlib, hashcash
+import urllib2, os, sys, time, random, sys, hashlib
 # It is OK to use the upstream M2Crypto here instead of our modified
 # version.
-# hashcash.py here should be a symlink to ../server-ca/hashcash.py
 
-difficulty = 20
-# TODO: unfortunately, the C hashcash implementation seems to be about
-#       2^6 times faster than the native Python implementation, so
-#       calibrating the difficulty is a bit of a problem.
+difficulty = 23   # bits of hashcash to generate
 
 def sha256(m):
     return hashlib.sha256(m).hexdigest()
@@ -66,6 +62,8 @@ def make_request(m, csr):
     m.request.timestamp = int(time.time())
     m.request.csr = csr
     m.request.clientpuzzle = hashcash.mint(server, difficulty)
+    hashcash_command = "hashcash -P -m -b %d -r %s" % (difficulty, server)
+    m.request.clientpuzzle = subprocess.check_output(hashcash_command.split(), shell=False).rstrip()
 
 def sign(key, m):
     m.request.sig = rsa_sign(key, ("(%d) (%s) (%s)" % (m.request.timestamp, m.request.recipient, m.request.csr)))
diff --git a/client-webserver/hashcash.py b/client-webserver/hashcash.py
deleted file mode 120000
index 3335450d4..000000000
--- a/client-webserver/hashcash.py
+++ /dev/null
@@ -1 +0,0 @@
-../server-ca/hashcash.py
\ No newline at end of file
diff --git a/server-ca/chocolate.py b/server-ca/chocolate.py
index 5113c0b12..42eede9fb 100755
--- a/server-ca/chocolate.py
+++ b/server-ca/chocolate.py
@@ -11,7 +11,7 @@ from google.protobuf.message import DecodeError
 MaximumSessionAge = 100   # seconds, to demonstrate session timeout
 MaximumChallengeAge = 600 # to demonstrate challenge timeout
 
-difficulty = 20           # bits of hashcash required with new requests
+difficulty = 23           # bits of hashcash required with new requests
 
 try:
     chocolate_server_name = open("SERVERNAME").read().rstrip()