From c6d9969109c6a1ea00b3d93abaedf23b4d9d9aaf Mon Sep 17 00:00:00 2001
From: Guillaume BINET <gbin@gootz.net>
Date: Thu, 6 Dec 2012 17:04:09 -0800
Subject: [PATCH] basic crypto for paging

---
 flask_restful/paging.py       |  0
 flask_restful/utils/crypto.py | 26 ++++++++++++++++++++++++++
 tests/test_crypto.py          | 10 ++++++++++
 3 files changed, 36 insertions(+)
 create mode 100644 flask_restful/paging.py
 create mode 100644 flask_restful/utils/crypto.py
 create mode 100644 tests/test_crypto.py

diff --git a/flask_restful/paging.py b/flask_restful/paging.py
new file mode 100644
index 00000000..e69de29b
diff --git a/flask_restful/utils/crypto.py b/flask_restful/utils/crypto.py
new file mode 100644
index 00000000..1656512e
--- /dev/null
+++ b/flask_restful/utils/crypto.py
@@ -0,0 +1,26 @@
+
+from Crypto.Cipher import AES
+from base64 import b64encode, b64decode
+
+BLOCK_SIZE = 16
+INTERRUPT = '\0'  # something impossible to put in a string
+PADDING = '\1'
+
+def pad(data):
+    return data + INTERRUPT + PADDING * (BLOCK_SIZE - (len(data) + 1) % BLOCK_SIZE)
+
+def strip(data):
+    return data.rstrip(PADDING).rstrip(INTERRUPT)
+
+def create_cipher(key, seed):
+    if len(seed) != 16:
+        raise ValueError("Choose a seed of 16 bytes")
+    if len(key) != 32:
+        raise ValueError("Choose a key of 32 bytes")
+    return AES.new(key, AES.MODE_CBC, seed)
+
+def encrypt(plaintext_data, key, seed):
+    return b64encode(create_cipher(key, seed).encrypt(pad(plaintext_data)))
+
+def decrypt(encrypted_data, key, seed):
+    return strip(create_cipher(key, seed).decrypt(b64decode(encrypted_data)))
\ No newline at end of file
diff --git a/tests/test_crypto.py b/tests/test_crypto.py
new file mode 100644
index 00000000..55518d39
--- /dev/null
+++ b/tests/test_crypto.py
@@ -0,0 +1,10 @@
+import unittest
+from flask_restful.utils.crypto import encrypt, decrypt
+
+
+class CryptoTestCase(unittest.TestCase):
+    def test_encrypt_decrypt(self):
+        key = '0123456789abcdef0123456789abcdef'
+        seed = 'deadbeefcafebabe'
+        message = 'It should go through'
+        self.assertEqual(decrypt(encrypt(message, key, seed), key, seed), message)
\ No newline at end of file