Basic authentication tools using py-bcrypt

mediagoblin/auth/lib.py

@@ -0,0 +1,66 @@
+# GNU Mediagoblin -- federated, autonomous media hosting
+# Copyright (C) 2011 Free Software Foundation, Inc
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program 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 Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+
+import bcrypt
+
+
+def bcrypt_check_password(raw_pass, stored_hash, extra_salt=None):
+    """
+    Check to see if this password matches.
+
+    Args:
+    - raw_pass: user submitted password to check for authenticity.
+    - stored_hash: The hash of the raw password (and possibly extra
+      salt) to check against
+    - extra_salt: (optional) If this password is with stored with a
+      non-database extra salt (probably in the config file) for extra
+      security, factor this into the check.
+
+    Returns:
+      True or False depending on success.
+    """
+    if extra_salt:
+        raw_pass = u"%s:%s" % (extra_salt, raw_pass)
+
+    hashed_pass = bcrypt.hashpw(raw_pass, stored_hash)
+
+    # Reduce risk of timing attacks by hashing again with a random
+    # number (thx to zooko on this advice, which I hopefully
+    # incorporated right.)
+    #
+    # See also: 
+    rand_salt = bcrypt.gensalt(5)
+    randplus_stored_hash = bcrypt.hashpw(stored_hash, rand_salt)
+    randplus_hashed_pass = bcrypt.hashpw(hashed_pass, rand_salt)
+
+    return randplus_stored_hash == randplus_hashed_pass
+
+
+def bcrypt_gen_password_hash(raw_pass, extra_salt=None):
+    """
+    Generate a salt for this new password.
+
+    Args:
+    - raw_pass: user submitted password
+    - extra_salt: (optional) If this password is with stored with a
+      non-database extra salt
+    """
+    if extra_salt:
+        raw_pass = u"%s:%s" % (extra_salt, raw_pass)
+
+    return bcrypt.hashpw(raw_pass, bcrypt.gensalt())

setup.py

@@ -33,6 +33,7 @@ setup(
         'mongokit',
         'webob',
         'wtforms',
+        'py-bcrypt',
         ],
 
     license = 'AGPLv3',