From 99ee63f8247a7c89ca1180838db1a4974812ed23 Mon Sep 17 00:00:00 2001
From: Lars Wirzenius <liw@liw.fi>
Date: Sat, 4 Aug 2018 12:59:18 +0300
Subject: Add: NonceGenerator

---
 qvisqve/noncegen.py       | 29 +++++++++++++++++++++++++++++
 qvisqve/noncegen_tests.py | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+)
 create mode 100644 qvisqve/noncegen.py
 create mode 100644 qvisqve/noncegen_tests.py

diff --git a/qvisqve/noncegen.py b/qvisqve/noncegen.py
new file mode 100644
index 0000000..295b7c8
--- /dev/null
+++ b/qvisqve/noncegen.py
@@ -0,0 +1,29 @@
+# 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/>.
+
+
+# Generate unique, hard-to-predict, single-use secure codes for
+# nonces. These can be used to prevent replay attacks, and such.
+#
+# We use uuid4 as nonces.
+
+
+import uuid
+
+
+class NonceGenerator:
+
+    def create_nonce(self):
+        return str(uuid.uuid4())
diff --git a/qvisqve/noncegen_tests.py b/qvisqve/noncegen_tests.py
new file mode 100644
index 0000000..1a0cf74
--- /dev/null
+++ b/qvisqve/noncegen_tests.py
@@ -0,0 +1,34 @@
+# 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
+
+
+class NonceGeneratorTests(unittest.TestCase):
+
+    def test_returns_a_string(self):
+        gen = qvisqve.NonceGenerator()
+        nonce = gen.create_nonce()
+        self.assertTrue(isinstance(nonce, str))
+
+    def test_returns_a_new_string_every_time(self):
+        gen = qvisqve.NonceGenerator()
+        nonce = gen.create_nonce()
+        for i in range(1000):
+            new = gen.create_nonce()
+            self.assertNotEqual(nonce, new)
-- 
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