Decode minikeys (like Casascius coin ones)

README.md

@@ -36,6 +36,7 @@ library. Non-consensus critical modules include the following:
     bitcoin.bloom    - Bloom filters (incomplete)
     bitcoin.net      - Network communication (in flux)
     bitcoin.messages - Network messages (in flux)
+    bitcoin.minikey  - Minikey decoding
     bitcoin.rpc      - Bitcoin Core RPC interface support
     bitcoin.wallet   - Wallet-related code, currently Bitcoin address and
                        private key support

bitcoin/minikey.py

@@ -0,0 +1,50 @@
+# Copyright (C) 2013-2014 The python-bitcoinlib developers
+#
+# This file is part of python-bitcoinlib.
+#
+# It is subject to the license terms in the LICENSE file found in the top-level
+# directory of this distribution.
+#
+# No part of python-bitcoinlib, including this file, may be copied, modified,
+# propagated, or distributed except according to the terms contained in the
+# LICENSE file.
+
+"""
+Minikey Handling
+
+Minikeys are an old key format, for details see
+https://en.bitcoin.it/wiki/Mini_private_key_format.
+"""
+
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+import sys
+_bord = (lambda x: x) if sys.version > '3' else ord
+
+from hashlib import sha256
+
+from bitcoin.wallet import CBitcoinSecret
+
+class InvalidMinikeyError(Exception):
+    """Raised for invalid minikeys"""
+    pass
+
+def decode_minikey(minikey):
+    """Decode minikey from str or bytes to a CBitcoinSecret"""
+    if isinstance(minikey, str):
+        minikey = minikey.encode('ascii')
+    length = len(minikey)
+    if length not in [22, 30]:
+        raise InvalidMinikeyError('Minikey length %d is not 22 or 30' % length)
+    h0 = sha256(minikey)
+    h1 = h0.copy()
+    h1.update(b'?')
+    checksum = _bord(h1.digest()[0])
+    if checksum != 0:
+        raise InvalidMinikeyError('Minikey checksum %s is not 0' % checksum)
+    return CBitcoinSecret.from_secret_bytes(h0.digest(), False)
+
+__all__ = (
+        'InvalidMinikeyError',
+        'decode_minikey'
+)

bitcoin/tests/test_minikey.py

@@ -0,0 +1,50 @@
+# Copyright (C) 2013-2014 The python-bitcoinlib developers
+#
+# This file is part of python-bitcoinlib.
+#
+# It is subject to the license terms in the LICENSE file found in the top-level
+# directory of this distribution.
+#
+# No part of python-bitcoinlib, including this file, may be copied, modified,
+# propagated, or distributed except according to the terms contained in the
+# LICENSE file.
+
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+import unittest
+
+from bitcoin.minikey import *
+from bitcoin.wallet import CBitcoinSecret
+
+class Test_minikey(unittest.TestCase):
+
+    valid_minikeys = [
+        ('S6c56bnXQiBjk9mqSYE7ykVQ7NzrRy', '5JPy8Zg7z4P7RSLsiqcqyeAF1935zjNUdMxcDeVrtU1oarrgnB7'),
+        ('SVY4eSFCF4tMtMohEkpXkoN9FHxDV7', '5JSyovgwfVcuFZBAp8LAta2tMsmscxXv3FvzvJWeKBfycLAmjuZ'),
+        ('S6c56bnXQiBjk9mqSYEa30', '5KM4V1haDBMEcgzPuAWdHSBAVAEJNp4he2meirV3JNvZz9aWBNH')
+    ]
+    invalid_minikeys = [
+        ('', 'Minikey length 0 is not 22 or 30'),
+        ('S6c56bnXQiBjk9mqSYE7ykVQ7NzrR', 'Minikey length 29 is not 22 or 30'),
+        ('S6c56bnXQiBjk9mqSYE7ykVQ7NzrRyz', 'Minikey length 31 is not 22 or 30'),
+        ('S6c56bnXQiBjk9mqSYE7ykVQ7NzrRz', 'Minikey checksum 213 is not 0'),
+        ('S6c56bnXQiBjk9mqSYE7yk', 'Minikey checksum 46 is not 0')
+    ]
+
+    def test_decode_minikey_bytes(self):
+        for minikey, exp_base58_key in self.valid_minikeys:
+            secret_key = decode_minikey(minikey.encode('ascii'))
+            self.assertIsInstance(secret_key, CBitcoinSecret)
+            self.assertEqual(str(secret_key), exp_base58_key)
+
+    def test_decode_minikey_str(self):
+        for minikey, exp_base58_key in self.valid_minikeys:
+            secret_key = decode_minikey(minikey)
+            self.assertIsInstance(secret_key, CBitcoinSecret)
+            self.assertEqual(str(secret_key), exp_base58_key)
+
+    def test_invalid(self):
+        for minikey, msg in self.invalid_minikeys:
+            with self.assertRaises(InvalidMinikeyError) as cm:
+                decode_minikey(minikey)
+            self.assertEqual(str(cm.exception), msg)

examples/minikey.py

@@ -0,0 +1,35 @@
+#!/usr/bin/env python3
+#
+# Copyright (C) 2013-2015 The python-bitcoinlib developers
+#
+# This file is part of python-bitcoinlib.
+#
+# It is subject to the license terms in the LICENSE file found in the top-level
+# directory of this distribution.
+#
+# No part of python-bitcoinlib, including this file, may be copied, modified,
+# propagated, or distributed except according to the terms contained in the
+# LICENSE file.
+
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+from bitcoin.minikey import decode_minikey
+
+def parser():
+    import argparse
+    parser = argparse.ArgumentParser(
+        description='Decode a minikey to base58 format.',
+        epilog='Security warning: arguments may be visible to other users on the same host.')
+    parser.add_argument(
+        'minikey',
+        help='the minikey')
+    return parser
+
+if __name__ == '__main__':
+    args = parser().parse_args()
+    try:
+        secret_key = str(decode_minikey(args.minikey))
+        print(secret_key)
+    except Exception as error:
+        print('%s: %s' % (error.__class__.__name__, str(error)))
+        exit(1)