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import sys
import hmac
import random
from base64 import b64encode, b64decode
from sleekxmpp.thirdparty.suelta.util import hash, bytes, num_to_bytes, bytes_to_num, XOR
from sleekxmpp.thirdparty.suelta.sasl import Mechanism, register_mechanism
from sleekxmpp.thirdparty.suelta.exceptions import SASLError, SASLCancelled
def parse_challenge(challenge):
"""
"""
items = {}
for key, value in [item.split(b'=', 1) for item in challenge.split(b',')]:
items[key] = value
return items
class SCRAM_HMAC(Mechanism):
"""
"""
def __init__(self, sasl, name):
"""
"""
super(SCRAM_HMAC, self).__init__(sasl, name, 0)
self._cb = False
if name[-5:] == '-PLUS':
name = name[:-5]
self._cb = True
self.hash = hash(self.name[6:])
if self.hash is None:
raise SASLCancelled(self.sasl, self)
if not self.sasl.tls_active():
if not self.sasl.sec_query(self, '-ENCRYPTION, SCRAM'):
raise SASLCancelled(self.sasl, self)
self._step = 0
self._rspauth = False
def HMAC(self, key, msg):
"""
"""
return hmac.HMAC(key=key, msg=msg, digestmod=self.hash).digest()
def Hi(self, text, salt, iterations):
"""
"""
text = bytes(text)
ui_1 = self.HMAC(text, salt + b'\0\0\0\01')
ui = ui_1
for i in range(iterations - 1):
ui_1 = self.HMAC(text, ui_1)
ui = XOR(ui, ui_1)
return ui
def H(self, text):
"""
"""
return self.hash(text).digest()
def prep(self):
if 'password' in self.values:
del self.values['password']
def process(self, challenge=None):
"""
"""
steps = {
0: self.process_one,
1: self.process_two,
2: self.process_three
}
return steps[self._step](challenge)
def process_one(self, challenge):
"""
"""
vitals = ['username']
if 'SaltedPassword' not in self.values:
vitals.append('password')
if 'Iterations' not in self.values:
vitals.append('password')
self.check_values(vitals)
username = bytes(self.values['username'])
self._step = 1
self._cnonce = bytes(('%s' % random.random())[2:])
self._soup = b'n=' + username + b',r=' + self._cnonce
self._gs2header = b''
if not self.sasl.tls_active():
if self._cb:
self._gs2header = b'p=tls-unique,,'
else:
self._gs2header = b'y,,'
else:
self._gs2header = b'n,,'
return self._gs2header + self._soup
def process_two(self, challenge):
"""
"""
data = parse_challenge(challenge)
self._step = 2
self._soup += b',' + challenge + b','
self._nonce = data[b'r']
self._salt = b64decode(data[b's'])
self._iter = int(data[b'i'])
if self._nonce[:len(self._cnonce)] != self._cnonce:
raise SASLCancelled(self.sasl, self)
cbdata = self.sasl.tls_active()
c = self._gs2header
if not cbdata and self._cb:
c += None
r = b'c=' + b64encode(c).replace(b'\n', b'')
r += b',r=' + self._nonce
self._soup += r
if 'Iterations' in self.values:
if self.values['Iterations'] != self._iter:
if 'SaltedPassword' in self.values:
del self.values['SaltedPassword']
if 'Salt' in self.values:
if self.values['Salt'] != self._salt:
if 'SaltedPassword' in self.values:
del self.values['SaltedPassword']
self.values['Iterations'] = self._iter
self.values['Salt'] = self._salt
if 'SaltedPassword' not in self.values:
self.check_values(['password'])
password = bytes(self.values['password'])
salted_pass = self.Hi(password, self._salt, self._iter)
self.values['SaltedPassword'] = salted_pass
salted_pass = self.values['SaltedPassword']
client_key = self.HMAC(salted_pass, b'Client Key')
stored_key = self.H(client_key)
client_sig = self.HMAC(stored_key, self._soup)
client_proof = XOR(client_key, client_sig)
r += b',p=' + b64encode(client_proof).replace(b'\n', b'')
server_key = self.HMAC(self.values['SaltedPassword'], b'Server Key')
self.server_sig = self.HMAC(server_key, self._soup)
return r
def process_three(self, challenge=None):
"""
"""
data = parse_challenge(challenge)
if b64decode(data[b'v']) == self.server_sig:
self._rspauth = True
def okay(self):
"""
"""
return self._rspauth
def get_user(self):
return self.values['username']
register_mechanism('SCRAM-', 60, SCRAM_HMAC)
register_mechanism('SCRAM-', 70, SCRAM_HMAC, extra='-PLUS')
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