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