Rename: to Qvisqve

3 files changed, 196 insertions, 0 deletions

diff --git a/qvisqve_secrets/__init__.py b/qvisqve_secrets/__init__.py
new file mode 100644
index 0000000..d2eeaf3
--- /dev/null
+++ b/qvisqve_secrets/__init__.py
@@ -0,0 +1,17 @@
+# Copyright (C) 2017  Lars Wirzenius
+#
+# 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/>.
+
+
+from .secrets import SecretHasher
diff --git a/qvisqve_secrets/secrets.py b/qvisqve_secrets/secrets.py
new file mode 100644
index 0000000..b469ed8
--- /dev/null
+++ b/qvisqve_secrets/secrets.py
@@ -0,0 +1,90 @@
+# Copyright (C) 2018  Lars Wirzenius
+#
+# 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 codecs
+
+
+from Cryptodome.Random import get_random_bytes
+from Cryptodome.Protocol.KDF import scrypt
+
+
+class SecretHasher:
+
+    # The following have been chosen based on:
+    # https://www.pycryptodome.org/en/latest/src/protocol/kdf.html
+    # Corrections, with references, welcome.
+    _salt_size = 16
+    _key_len = 128
+    _N = 16384
+    _r = 8
+    _p = 1
+
+    _version = 1
+
+    _ok_args = ['salt', 'key_len', 'N', 'r', 'p']
+
+    def get_salt(self):
+        return get_random_bytes(self._salt_size)
+
+    def set_n(self, n):
+        self._N = n
+
+    def _full_hash(self, cleartext, **kwargs):
+        assert kwargs == self._filter_kwargs(kwargs)
+
+        hashed_binary = scrypt(cleartext, **kwargs)
+        params = {
+            'version': self._version,
+            'hash': self.hex_encode(hashed_binary),
+            'salt': self.hex_encode(kwargs['salt'])
+        }
+        for key in kwargs:
+            if key not in params:
+                params[key] = kwargs[key]
+
+        return params
+
+    def hex_encode(self, byte_string):
+        return codecs.encode(byte_string, 'hex').decode('ascii')
+
+    def hex_decode(self, hex_string):
+        return codecs.decode(bytes(hex_string, 'ascii'), 'hex')
+
+    def _filter_kwargs(self, kwargs):
+        return {
+            key: kwargs[key]
+            for key in self._ok_args
+        }
+
+    def hash(self, cleartext, salt=None):
+        if salt is None:
+            salt = self.get_salt()
+        assert isinstance(salt, bytes)
+
+        kwargs = {
+            'salt': salt,
+            'key_len': self._key_len,
+            'N': self._N,
+            'r': self._r,
+            'p': self._p,
+        }
+        return self._full_hash(cleartext, **kwargs)
+
+    def is_correct(self, hashed, cleartext):
+        kwargs = self._filter_kwargs(hashed)
+        salt = self.hex_decode(kwargs.pop('salt'))
+        h2 = self._full_hash(cleartext, salt=salt, **kwargs)
+        return hashed == h2
diff --git a/qvisqve_secrets/secrets_tests.py b/qvisqve_secrets/secrets_tests.py
new file mode 100644
index 0000000..e7cce87
--- /dev/null
+++ b/qvisqve_secrets/secrets_tests.py
@@ -0,0 +1,89 @@
+# Copyright (C) 2018  Lars Wirzenius
+#
+# 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 unittest
+
+
+import qvisqve_secrets
+
+
+class SecretHasherTests(unittest.TestCase):
+
+    def test_byte_string_survives_hex_roundtrip(self):
+        byte_string = b'\x00\x02\x03'
+        sh = qvisqve_secrets.SecretHasher()
+        encoded = sh.hex_encode(byte_string)
+        self.assertEqual(byte_string, sh.hex_decode(encoded))
+
+    def test_returns_sufficiently_long_salt(self):
+        sh = qvisqve_secrets.SecretHasher()
+        salt = sh.get_salt()
+        self.assertTrue(len(salt) >= 8)
+
+    def test_produces_a_hash(self):
+        cleartext = 'hunter2'
+        salt = b'nacl'
+        sh = qvisqve_secrets.SecretHasher()
+        hashed = sh.hash(cleartext, salt)
+        self.assertTrue(isinstance(hashed, dict))
+
+    def test_produces_a_hash_with_salt(self):
+        cleartext = 'hunter2'
+        sh = qvisqve_secrets.SecretHasher()
+        hashed = sh.hash(cleartext)
+        self.assertTrue(isinstance(hashed, dict))
+
+    def test_produces_same_hash_for_same_input(self):
+        cleartext = 'hunter2'
+        salt = b'nacl'
+        sh = qvisqve_secrets.SecretHasher()
+        hashed1 = sh.hash(cleartext, salt)
+        hashed2 = sh.hash(cleartext, salt)
+        self.assertEqual(hashed1, hashed2)
+
+    def test_produces_different_hashes_for_different_cleartext(self):
+        sh = qvisqve_secrets.SecretHasher()
+        salt = b'nacl'
+        hashed1 = sh.hash('hunter2', salt)
+        hashed2 = sh.hash('swordfish', salt)
+        self.assertNotEqual(hashed1, hashed2)
+
+    def test_produces_different_hashes_for_same_cleartext(self):
+        sh = qvisqve_secrets.SecretHasher()
+        hashed1 = sh.hash('hunter2', b'nacl')
+        hashed2 = sh.hash('hunter2', b'nh4cl')
+        self.assertNotEqual(hashed1, hashed2)
+
+    def test_accepts_correct_password(self):
+        cleartext = 'hunter2'
+        sh = qvisqve_secrets.SecretHasher()
+        hashed = sh.hash(cleartext, b'nacl')
+        self.assertTrue(sh.is_correct(hashed, cleartext))
+
+    def test_rejects_incorrect_password(self):
+        cleartext = 'swordfish'
+        sh = qvisqve_secrets.SecretHasher()
+        hashed = sh.hash(cleartext, b'nacl')
+        self.assertTrue(sh.is_correct(hashed, cleartext))
+
+    def test_handles_parameter_changes(self):
+        cleartext = 'hunter2'
+        salt = b'nacl'
+        sh = qvisqve_secrets.SecretHasher()
+        hashed = sh.hash(cleartext, salt)
+        sh.set_n(2**1)
+        self.assertTrue(sh.is_correct(hashed, cleartext))
+        self.assertNotEqual(sh.hash(cleartext, salt), hashed)