desktop.py

#!/usr/bin/python

# We are the Desktop

import sys, simplejson, time, urllib2, hmac, base64
from jpake import JPAKE, params_80, params_112, params_128
from M2Crypto.EVP import Cipher

def get(url, etag = None):
    headers = {}
    if etag:
        headers['If-None-Match'] = etag
    request = urllib2.Request(url, None, headers)
    response = urllib2.urlopen(request)
    data = response.read()
    return simplejson.loads(data)

def put(url, data):

    opener = urllib2.build_opener(urllib2.HTTPHandler)
    json = simplejson.dumps(data)
    request = urllib2.Request(url, data=json)
    request.add_header('Content-Type', 'application/json')
    request.get_method = lambda: 'PUT'
    response = urllib2.urlopen(request)
    return response.info().getheader('Etag')

def encrypt(data, key, iv):
    cipher = Cipher(alg='aes_256_cbc', key=key, iv=iv, op=1)
    res = cipher.update(data)
    res += cipher.final()
    return res

def decrypt(data, key, iv):
    cipher = Cipher(alg='aes_256_cbc', key=key, iv=iv, op=0)
    res = cipher.update(data)
    res += cipher.final()
    return res    

password = sys.argv[1]
url = "http://wopr.local:5000/%s" % password

print "X Password = %s" % password
print "X URL = %s" % url

j = JPAKE(password, signerid="Desktop", params=params_80)

# Get Server.Message1

print "X Getting Server.Message1"
server_one = get(url)
#print "X Got Server.Message1: %s" % str(server_one)

# Generate and Put Client.Message1

print "X Putting Client.Message1"
client_one = j.one()
client_one_etag = put(url, client_one)
#print "X Put Client.Message1 (etag=%s) %s" % (client_one_etag, client_one)

# Get Server.Message2

print "X Getting Server.Message2"
while True:
    try:
        server_two = get(url, client_one_etag)
        break
    except urllib2.HTTPError, e:
        if e.code == 304:
            print "X Did not get right response yet. Trying again."
            pass
        else:
            raise
    time.sleep(5)        
#print "X Got Server.Message2: %s" % server_two

# Generate Client.Message2

print "X Generating Client.Message2"
client_two = j.two(server_one)

# Generate the key

print "X Generating key"
key = j.three(server_two)
print "X Generated key: %s" % key

# Put Client.Message2

iv = '0123456780abcdef'
ct = encrypt(simplejson.dumps({ 'message': sys.argv[2] }), key, iv)
client_two['payload'] = { 'ciphertext': base64.b64encode(ct),
                          'iv': base64.b64encode(iv) }

print "X Putting Client.Message2"
client_two_etag = put(url, client_two)
#print "X Put Client.Message2 (etag=%s) %s" % (client_two_etag, client_two)