Merge #701: fix base58.decode_check()

c31eed9 fix base58.decode_check() (Marko Bencun)

Pull request description:

  The function used the full sha256 and not just the first four bytes to verify the checksum. As a result, the checksum check always fails.

  This breaks the BitBox02 multisig registration, which uses this function to decode xpubs. This broke when it switched to using the internal base58 library over the `base58` dependency in 674cb08.

  Fixes #700.

ACKs for top commit:
  achow101:
    ACK c31eed9

Tree-SHA512: 5a4687c38cc8cdaac4c284aa422b485f607d4f8b3d123c982bd4bb713ddfb5971b45c2de2357368494cf83b29b04401f0f4b740acf08adfd24b5ca78e86e02c7

hwilib/_base58.py

@@ -95,7 +95,7 @@ def decode_check(s: str) -> bytes:
     payload = data[:-4]
     checksum = data[-4:]
     calc_checksum = hash256(payload)
-    if checksum != calc_checksum:
+    if checksum != calc_checksum[:4]:
         raise ValueError("Invalid checksum")
     return payload
 

test/test_base58.py

@@ -28,6 +28,24 @@
         "1cWB5HCBdLjAuqGGReWE3R3CguuwSjw6RHn39s2yuDRTS5NsBgNiFpWgAnEx6VQi8csexkgYw3mdYrMHr8x9i7aEwP8kZ7vccXWqKDvGv3u1GxFKPuAkn8JCPPGDMf3vMMnbzm6Nh9zh1gcNsMvH3ZNLmP5fSG6DGbbi2tuwMWPthr4boWwCxf7ewSgNQeacyozhKDDQQ1qL5fQFUW52QKUZDZ5fw3KXNQJMcNTcaB723LchjeKun7MuGW5qyCBZYzA1KjofN1gYBV3NqyhQJ3Ns746GNuf9N2pQPmHz4xpnSrrfCvy6TVVz5d4PdrjeshsWQwpZsZGzvbdAdN8MKV5QsBDY")
 ]
 
+# Test vectors for encode_check and decode_check
+TEST_VECTORS_CHECK: List[Tuple[str, str]] = [
+    ("", "3QJmnh"),
+    ("61", "C2dGTwc"),
+    ("626262", "4jF5uERJAK"),
+    ("636363", "4mT4krqUYJ"),
+    ("73696d706c792061206c6f6e6720737472696e67", "BXF1HuEUCqeVzZdrKeJjG74rjeXxqJ7dW"),
+    ("00eb15231dfceb60925886b67d065299925915aeb172c06647", "13REmUhe2ckUKy1FvM7AMCdtyYq831yxM3QeyEu4"),
+    ("516b6fcd0f", "237LSrY9NUUas"),
+    ("bf4f89001e670274dd", "GwDDDeduj1jpykc27e"),
+    ("572e4794", "FamExfqCeza"),
+    ("ecac89cad93923c02321", "2W1Yd5Zu6WGyKVtHGMrH"),
+    ("10c8511e", "3op3iuGMmhs"),
+    ("00000000000000000000", "111111111146Momb"),
+    ("000111d38e5fc9071ffcd20b4a763cc9ae4f252bb4e48fd66a835e252ada93ff480d6dd43dc62a641155a5", "17mxz9b2TuLnDf6XyQrHjAc3UvMoEg7YzRsJkBd4VwNpFh8a1StKmCe5WtAW27Y"),
+    ("000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff", "151KWPPBRzdWPr1ASeu172gVgLf1YfUp6VJyk6K9t4cLqYtFHcMa2iX8S3NJEprUcW7W5LvaPRpz7UG7puBj5STE3nKhCGt5eckYq7mMn5nT7oTTic2BAX6zDdqrmGCnkszQkzkz8e5QLGDjf7KeQgtEDm4UER6DMSdBjFQVa6cHrrJn9myVyyhUrsVnfUk2WmNFZvkWv3Tnvzo2cJ1xW62XDfUgYz1pd97eUGGPuXvDFfLsBVd1dfdUhPwxW7pMPgdWHTmg5uqKGFF6vE4xXpAqZTbTxRZjCDdTn68c2wrcxApm8hq3JX65Hix7VtcD13FF8b7BzBtwjXq1ze6NMjKgUcqpGV5XA5"),
+]
+
 class TestBase58(unittest.TestCase):
     """Unit test class for base58 encoding and decoding."""
 
@@ -45,5 +63,19 @@ def test_encoding(self):
             encoded: str = base58.encode(unhexlify(pair[0]))
             self.assertEqual(encoded, pair[1])
 
+    def test_check_decoding(self):
+        """Test base58 check decoding"""
+
+        for pair in TEST_VECTORS_CHECK:
+            decoded: bytes = base58.decode_check(pair[1])
+            self.assertEqual(decoded, unhexlify(pair[0]))
+
+    def test_check_encoding(self):
+        """Test base58 check encoding"""
+
+        for pair in TEST_VECTORS_CHECK:
+            encoded: str = base58.encode_check(unhexlify(pair[0]))
+            self.assertEqual(encoded, pair[1])
+
 if __name__ == "__main__":
     unittest.main()