From d4091dbde641dc9796b51e032ea23a0ba5c1fcbb Mon Sep 17 00:00:00 2001
From: Lance Stout <lancestout@gmail.com>
Date: Wed, 3 Aug 2011 17:00:51 -0700
Subject: Integrate a modified version of Dave Cridland's Suelta SASL library.

---
 .../thirdparty/suelta/mechanisms/scram_hmac.py     | 176 +++++++++++++++++++++
 1 file changed, 176 insertions(+)
 create mode 100644 sleekxmpp/thirdparty/suelta/mechanisms/scram_hmac.py

(limited to 'sleekxmpp/thirdparty/suelta/mechanisms/scram_hmac.py')

diff --git a/sleekxmpp/thirdparty/suelta/mechanisms/scram_hmac.py b/sleekxmpp/thirdparty/suelta/mechanisms/scram_hmac.py
new file mode 100644
index 00000000..e0020329
--- /dev/null
+++ b/sleekxmpp/thirdparty/suelta/mechanisms/scram_hmac.py
@@ -0,0 +1,176 @@
+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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