[Fedor Brunner] Use better random number generator when openssl is available. Fixes #12

3 files changed, 57 insertions, 9 deletions

diff --git a/nbxmpp/auth_nb.py b/nbxmpp/auth_nb.py
index 720fac2..aaa8d0b 100644
--- a/nbxmpp/auth_nb.py
+++ b/nbxmpp/auth_nb.py
@@ -27,7 +27,6 @@ from .protocol import Node, NodeProcessed, isResultNode, Iq, Protocol, JID
 from .plugin import PlugIn
 from .smacks import Smacks
 import base64
-import random
 import itertools
 from . import dispatcher_nb
 import hashlib
@@ -37,6 +36,8 @@ import hashlib
 import logging
 log = logging.getLogger('nbxmpp.auth_nb')
 
+import rndg
+
 def HH(some): return hashlib.md5(some).hexdigest()
 def H(some): return hashlib.md5(some).digest()
 def C(some): return b':'.join(some)
@@ -440,8 +441,7 @@ class SASL(PlugIn):
             else:
                 self.resp['realm'] = self._owner.Server
             self.resp['nonce'] = chal['nonce']
-            self.resp['cnonce'] = ''.join("%x" % randint(0, 2**28) for randint \
-                in itertools.repeat(random.randint, 7))
+            self.resp['cnonce'] = '%x' % rngd.getrandbits(196)
             self.resp['nc'] = ('00000001')
             self.resp['qop'] = 'auth'
             self.resp['digest-uri'] = 'xmpp/' + self._owner.Server
@@ -471,8 +471,7 @@ class SASL(PlugIn):
     def set_password(self, password):
         self.password = '' if password is None else password
         if self.mechanism == 'SCRAM-SHA-1':
-            nonce = ''.join('%x' % randint(0, 2 ** 28) for randint in \
-                itertools.repeat(random.randint, 7))
+            nonce = '%x' % rndg.getrandbits(196)
             self.scram_soup = 'n=' + self.username + ',r=' + nonce
             self.scram_gs2 = 'n,,' # No CB yet.
             sasl_data = base64.b64encode((self.scram_gs2 + self.scram_soup).\
diff --git a/nbxmpp/bosh.py b/nbxmpp/bosh.py
index 47b1784..6eb5877 100644
--- a/nbxmpp/bosh.py
+++ b/nbxmpp/bosh.py
@@ -18,7 +18,7 @@
 ## along with Gajim.  If not, see <http://www.gnu.org/licenses/>.
 
 
-import locale, random
+import locale
 from hashlib import sha1
 from .transports_nb import NonBlockingTransport, NonBlockingHTTPBOSH,\
         CONNECTED, CONNECTING, DISCONNECTED, DISCONNECTING,\
@@ -29,6 +29,8 @@ from .simplexml import Node
 import logging
 log = logging.getLogger('nbxmpp.bosh')
 
+import rndg
+
 KEY_COUNT = 10
 
 # Fake file descriptor - it's used for setting read_timeout in idlequeue for
@@ -486,9 +488,7 @@ def get_rand_number():
     # to 7881299347898368 messages to raise rid over 2**53
     # (see http://www.xmpp.org/extensions/xep-0124.html#rids)
     # it's also used for sequence key initialization
-    r = random.Random()
-    r.seed()
-    return r.getrandbits(50)
+    return rndg.getrandbits(50)
 
 
 
diff --git a/nbxmpp/rndg.py b/nbxmpp/rndg.py
new file mode 100644
index 0000000..42d1851
--- /dev/null
+++ b/nbxmpp/rndg.py
@@ -0,0 +1,49 @@
+## rndg.py
+##
+##   cryptographically secure pseudo-random number generator.
+##   When possible use OpenSSL PRNG combined with os.random,
+##   if OpenSSL PRNG is not available, use only os.random.
+##
+## Copyright (C) 2013 Fedor Brunner <fedor.brunner@azet.sk>
+##
+## This file is part of Gajim.
+##
+## Gajim is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published
+## by the Free Software Foundation; version 3 only.
+##
+## Gajim is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with Gajim.  If not, see <http://www.gnu.org/licenses/>.
+
+USE_PYOPENSSL = False
+try:
+    import OpenSSL.rand
+    import binascii, os
+    USE_PYOPENSSL = True
+except ImportError:
+    import random
+
+if not USE_PYOPENSSL:
+    getrandbits = random.SystemRandom().getrandbits
+else:
+    def getrandbits(k):
+        """getrandbits(k) -> x.  Generates a long int with k random bits."""
+        if k <= 0:
+            raise ValueError('number of bits must be greater than zero')
+        if k != int(k):
+            raise TypeError('number of bits should be an integer')
+
+        bytes = (k + 7) // 8                    # bits / 8 and rounded up
+
+        # Add system entropy to OpenSSL PRNG
+        OpenSSL.rand.add(os.urandom(bytes), bytes)
+        # Extract random bytes from OpenSSL PRNG
+        random_str = OpenSSL.rand.bytes(bytes)
+
+        x = long(binascii.hexlify(random_str), 16)
+        return x >> (bytes * 8 - k)             # trim excess bits