Add custom base58check algorithm (#389)

lib/coins.py

@@ -70,6 +70,8 @@ class Coin(object):
     BLOCK_PROCESSOR = BlockProcessor
     XPUB_VERBYTES = bytes('????', 'utf-8')
     XPRV_VERBYTES = bytes('????', 'utf-8')
+    ENCODE_CHECK = Base58.encode_check
+    DECODE_CHECK = Base58.decode_check
     # Peer discovery
     PEER_DEFAULT_PORTS = {'t': '50001', 's': '50002'}
     PEERS = []
@@ -168,7 +170,7 @@ class Coin(object):
     def P2PKH_address_from_hash160(cls, hash160):
         '''Return a P2PKH address given a public key.'''
         assert len(hash160) == 20
-        return Base58.encode_check(cls.P2PKH_VERBYTE + hash160)
+        return cls.ENCODE_CHECK(cls.P2PKH_VERBYTE + hash160)
 
     @classmethod
     def P2PKH_address_from_pubkey(cls, pubkey):
@@ -179,7 +181,7 @@ class Coin(object):
     def P2SH_address_from_hash160(cls, hash160):
         '''Return a coin address given a hash160.'''
         assert len(hash160) == 20
-        return Base58.encode_check(cls.P2SH_VERBYTES[0] + hash160)
+        return cls.ENCODE_CHECK(cls.P2SH_VERBYTES[0] + hash160)
 
     @classmethod
     def multisig_address(cls, m, pubkeys):
@@ -212,7 +214,7 @@ class Coin(object):
 
         Pass the address (either P2PKH or P2SH) in base58 form.
         '''
-        raw = Base58.decode_check(address)
+        raw = cls.DECODE_CHECK(address)
 
         # Require version byte(s) plus hash160.
         verbyte = -1
@@ -233,7 +235,7 @@ class Coin(object):
         payload = bytearray(cls.WIF_BYTE) + privkey_bytes
         if compressed:
             payload.append(0x01)
-        return Base58.encode_check(payload)
+        return cls.ENCODE_CHECK(payload)
 
     @classmethod
     def header_hash(cls, header):

lib/hash.py

@@ -143,18 +143,18 @@ class Base58(object):
         return txt[::-1]
 
     @staticmethod
-    def decode_check(txt):
+    def decode_check(txt, *, hash_fn=double_sha256):
         '''Decodes a Base58Check-encoded string to a payload.  The version
         prefixes it.'''
         be_bytes = Base58.decode(txt)
         result, check = be_bytes[:-4], be_bytes[-4:]
-        if check != double_sha256(result)[:4]:
+        if check != hash_fn(result)[:4]:
             raise Base58Error('invalid base 58 checksum for {}'.format(txt))
         return result
 
     @staticmethod
-    def encode_check(payload):
+    def encode_check(payload, *, hash_fn=double_sha256):
         """Encodes a payload bytearray (which includes the version byte(s))
         into a Base58Check string."""
-        be_bytes = payload + double_sha256(payload)[:4]
+        be_bytes = payload + hash_fn(payload)[:4]
         return Base58.encode(be_bytes)

tests/lib/test_addresses.py

@@ -60,7 +60,7 @@ def test_address_to_hashX(address):
 def test_address_from_hash160(address):
     coin, addr, hash, _ = address
 
-    raw = Base58.decode_check(addr)
+    raw = coin.DECODE_CHECK(addr)
     verlen = len(raw) - 20
     assert verlen > 0
     verbyte, hash_bytes = raw[:verlen], raw[verlen:]

tests/lib/test_hash.py

@@ -1,6 +1,7 @@
 #
 # Tests of lib/hash.py
 #
+from functools import partial
 
 import pytest
 
@@ -66,3 +67,19 @@ def test_Base58_encode_check():
     with pytest.raises(TypeError):
         lib_hash.Base58.encode_check('foo')
     assert lib_hash.Base58.encode_check(b'foo') == '4t9WKfuAB8'
+
+def test_Base58_decode_check_custom():
+    decode_check_sha256 = partial(lib_hash.Base58.decode_check,
+                                  hash_fn=lib_hash.sha256)
+    with pytest.raises(TypeError):
+        decode_check_sha256(b'foo')
+    assert decode_check_sha256('4t9WFhKfWr') == b'foo'
+    with pytest.raises(lib_hash.Base58Error):
+        decode_check_sha256('4t9WFhKfWp')
+
+def test_Base58_encode_check_custom():
+    encode_check_sha256 = partial(lib_hash.Base58.encode_check,
+                                  hash_fn=lib_hash.sha256)
+    with pytest.raises(TypeError):
+        encode_check_sha256('foo')
+    assert encode_check_sha256(b'foo') == '4t9WFhKfWr'