Switch from using PyCrypto's Random to using os.urandom.

There's several reasons for this change:

1) It's faster for reads up to 1024 bytes (nearly 10x faster for 16 byte reads)
2) It receives considerably more security review since it's in the kernel.
3) It's yet another step towards running on PyPy.
4) Using userspace CSPRNGs is considered something of an anti-pattern. See:
   http://sockpuppet.org/blog/2014/02/25/safely-generate-random-numbers/
   http://webcache.googleusercontent.com/search?q=cache:2nTvpCgKZXIJ:www.2uo.de/myths-about-urandom/+&cd=3&hl=en&ct=clnk&gl=us

1 files changed, 9 insertions, 8 deletions

diff --git a/tests/test_kex.py b/tests/test_kex.py
index c522be46..56f1b7c7 100644
--- a/tests/test_kex.py
+++ b/tests/test_kex.py
@@ -21,7 +21,9 @@ Some unit tests for the key exchange protocols.
 """
 
 from binascii import hexlify
+import os
 import unittest
+
 import paramiko.util
 from paramiko.kex_group1 import KexGroup1
 from paramiko.kex_gex import KexGex
@@ -29,9 +31,8 @@ from paramiko import Message
 from paramiko.common import byte_chr
 
 
-class FakeRng (object):
-    def read(self, n):
-        return byte_chr(0xcc) * n
+def dummy_urandom(n):
+    return byte_chr(0xcc) * n
 
 
 class FakeKey (object):
@@ -41,7 +42,7 @@ class FakeKey (object):
     def asbytes(self):
         return b'fake-key'
 
-    def sign_ssh_data(self, rng, H):
+    def sign_ssh_data(self, H):
         return b'fake-sig'
 
 
@@ -53,8 +54,7 @@ class FakeModulusPack (object):
         return self.G, self.P
 
 
-class FakeTransport (object):
-    rng = FakeRng()
+class FakeTransport(object):
     local_version = 'SSH-2.0-paramiko_1.0'
     remote_version = 'SSH-2.0-lame'
     local_kex_init = 'local-kex-init'
@@ -91,10 +91,11 @@ class KexTest (unittest.TestCase):
     K = 14730343317708716439807310032871972459448364195094179797249681733965528989482751523943515690110179031004049109375612685505881911274101441415545039654102474376472240501616988799699744135291070488314748284283496055223852115360852283821334858541043710301057312858051901453919067023103730011648890038847384890504
 
     def setUp(self):
-        pass
+        self._original_urandom = os.urandom
+        os.urandom = dummy_urandom
 
     def tearDown(self):
-        pass
+        os.urandom = self._original_urandom
 
     def test_1_group1_client(self):
         transport = FakeTransport()