Add support for 160 bit ARC4 keys

1 files changed, 89 insertions, 0 deletions

diff --git a/docs/development/custom-vectors/arc4/generate_arc4.py b/docs/development/custom-vectors/arc4/generate_arc4.py
new file mode 100644
index 00000000..093bb49d
--- /dev/null
+++ b/docs/development/custom-vectors/arc4/generate_arc4.py
@@ -0,0 +1,89 @@
+# This file is dual licensed under the terms of the Apache License, Version
+# 2.0, and the BSD License. See the LICENSE file in the root of this repository
+# for complete details.
+
+from __future__ import absolute_import, division, print_function
+
+import binascii
+
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives import ciphers
+from cryptography.hazmat.primitives.ciphers import algorithms
+
+
+_RFC6229_KEY_MATERIALS = [
+    (True, 8*'0102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f20'),
+    (False, 8*'1ada31d5cf688221c109163908ebe51debb46227c6cc8b37641910833222772a')
+]
+
+
+_RFC6229_OFFSETS = [
+    0,
+    16,
+    240,
+    256,
+    496,
+    512,
+    752,
+    768,
+    1008,
+    1024,
+    1520,
+    1536,
+    2032,
+    2048,
+    3056,
+    3072,
+    4080,
+    4096
+]
+
+
+_SIZES_TO_GENERATE = [
+    160
+]
+
+
+def _key_for_size(size, keyinfo):
+    msb, key = keyinfo
+    if msb:
+        return key[:size//4]
+    else:
+        return key[-size//4:]
+
+
+def _build_vectors():
+    count = 0
+    output = []
+    key = None
+    plaintext = binascii.unhexlify(32*'0')
+    for size in _SIZES_TO_GENERATE:
+        for keyinfo in _RFC6229_KEY_MATERIALS:
+            key = _key_for_size(size, keyinfo)
+            cipher = ciphers.Cipher(algorithms.ARC4(binascii.unhexlify(key)), None, default_backend())
+            encryptor = cipher.encryptor()
+            current_offset = 0
+            for offset in _RFC6229_OFFSETS:
+                if offset % 16 != 0:
+                    raise ValueError("Offset {} is not evenly divisible by 16".format(offset))
+                while current_offset < offset:
+                    encryptor.update(plaintext)
+                    current_offset += len(plaintext)
+                output.append("\nCOUNT = {}".format(count))
+                count += 1
+                output.append("KEY = {}".format(key))
+                output.append("OFFSET = {}".format(offset))
+                output.append("PLAINTEXT = {}".format(binascii.hexlify(plaintext)))
+                output.append("CIPHERTEXT = {}".format(binascii.hexlify(encryptor.update(plaintext))))
+                current_offset += len(plaintext)
+            assert not encryptor.finalize()
+    return "\n".join(output)
+
+
+def _write_file(data, filename):
+    with open(filename, 'w') as f:
+        f.write(data)
+
+
+if __name__ == '__main__':
+    _write_file(_build_vectors(), 'arc4.txt')