base58.py

import sys, hashlib, binascii

__b58chars = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'
__b58base = len(__b58chars)

def b58encode_checksum(v):
	hash = binascii.hexlify(v) + hashlib.sha256(hashlib.sha256(v).digest()).hexdigest()[:8]
	return b58encode(binascii.unhexlify(hash))

def b58encode(v):

	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

	## Add leading 0s
	nPad = 0
	for c in v:
		if c == '\0': nPad += 1
		else: break

	return (__b58chars[0]*nPad) + result


def b58decode(v, length):

	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