105 lines
2.8 KiB
Python
105 lines
2.8 KiB
Python
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'''
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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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