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'''
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")
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