base58.py

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,) )

### BEGIN: Copied from https://bitcointalk.org/index.php?topic=1026.0 (public domain)
__b58chars = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'
__b58base = len(__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):
  """ 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 get_bcaddress_version(strAddress):
  """ Returns None if strAddress is invalid.  Otherwise returns integer version of address. """
  addr = b58decode(strAddress,25)
  if addr is None: return None
  version = addr[0]
  checksum = addr[-4:]
  vh160 = addr[:-4] # Version plus hash160 is what is checksummed                                                                                                    
  h3=SHA256.new(SHA256.new(vh160).digest()).digest()
  if h3[0:4] == checksum:
    return ord(version)
  return None
###   END: Copied from https://bitcointalk.org/index.php?topic=1026.0 (public domain)

if __name__ == '__main__':
	# Test case
	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")