data-driven base58 CBitcoinAddress/CBitcoinSecret tests

Arbitrary numbers of test vectors can be generated using the script
`gen_base58_test_vectors.py`.

contrib/testgen/base58.py

@@ -0,0 +1,104 @@
+'''
+Bitcoin base58 encoding and decoding.
+
+Based on https://bitcointalk.org/index.php?topic=1026.0 (public domain)
+'''
+import hashlib
+
+# for compatibility with following code...
+class SHA256:
+    new = hashlib.sha256
+
+if str != bytes:
+    # Python 3.x
+    def ord(c):
+        return c
+    def chr(n):
+        return bytes( (n,) )
+
+__b58chars = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'
+__b58base = len(__b58chars)
+b58chars = __b58chars
+
+def b58encode(v):
+    """ encode v, which is a string of bytes, to base58.
+    """
+    long_value = 0
+    for (i, c) in enumerate(v[::-1]):
+        long_value += (256**i) * ord(c)
+
+    result = ''
+    while long_value >= __b58base:
+        div, mod = divmod(long_value, __b58base)
+        result = __b58chars[mod] + result
+        long_value = div
+    result = __b58chars[long_value] + result
+
+    # Bitcoin does a little leading-zero-compression:
+    # leading 0-bytes in the input become leading-1s
+    nPad = 0
+    for c in v:
+        if c == '\0': nPad += 1
+        else: break
+
+    return (__b58chars[0]*nPad) + result
+
+def b58decode(v, length = None):
+    """ decode v into a string of len bytes
+    """
+    long_value = 0
+    for (i, c) in enumerate(v[::-1]):
+        long_value += __b58chars.find(c) * (__b58base**i)
+
+    result = bytes()
+    while long_value >= 256:
+        div, mod = divmod(long_value, 256)
+        result = chr(mod) + result
+        long_value = div
+    result = chr(long_value) + result
+
+    nPad = 0
+    for c in v:
+        if c == __b58chars[0]: nPad += 1
+        else: break
+
+    result = chr(0)*nPad + result
+    if length is not None and len(result) != length:
+        return None
+
+    return result
+
+def checksum(v):
+    """Return 32-bit checksum based on SHA256"""
+    return SHA256.new(SHA256.new(v).digest()).digest()[0:4]
+
+def b58encode_chk(v):
+    """b58encode a string, with 32-bit checksum"""
+    return b58encode(v + checksum(v))
+
+def b58decode_chk(v):
+    """decode a base58 string, check and remove checksum"""
+    result = b58decode(v)
+    if result is None:
+        return None
+    h3 = checksum(result[:-4])
+    if result[-4:] == checksum(result[:-4]):
+        return result[:-4]
+    else:
+        return None
+
+def get_bcaddress_version(strAddress):
+    """ Returns None if strAddress is invalid.  Otherwise returns integer version of address. """
+    addr = b58decode_chk(strAddress)
+    if addr is None or len(addr)!=21: return None
+    version = addr[0]
+    return ord(version)
+
+if __name__ == '__main__':
+    # Test case (from http://gitorious.org/bitcoin/python-base58.git)
+    assert get_bcaddress_version('15VjRaDX9zpbA8LVnbrCAFzrVzN7ixHNsC') is 0
+    _ohai = 'o hai'.encode('ascii')
+    _tmp = b58encode(_ohai)
+    assert _tmp == 'DYB3oMS'
+    assert b58decode(_tmp, 5) == _ohai
+    print("Tests passed")