Files
rippled/bin/python/ripple/util/Base58.py
Tom Ritchford 31d352b3aa Productionize manifest generator.
* Better output.
* Better error checking and reporting.
* Clearer names.
* Python style.
2015-05-28 07:22:34 -07:00

95 lines
2.8 KiB
Python

#!/usr/bin/env python
from hashlib import sha256
#
# Human strings are base-58 with a
# version prefix and a checksum suffix.
#
# Copied from ripple/protocol/RippleAddress.h
#
VER_NONE = 1
VER_NODE_PUBLIC = 28
VER_NODE_PRIVATE = 32
VER_ACCOUNT_ID = 0
VER_ACCOUNT_PUBLIC = 35
VER_ACCOUNT_PRIVATE = 34
VER_FAMILY_GENERATOR = 41
VER_FAMILY_SEED = 33
ALPHABET = 'rpshnaf39wBUDNEGHJKLM4PQRST7VWXYZ2bcdeCg65jkm8oFqi1tuvAxyz'
VERSION_NAME = {
VER_NONE: 'VER_NONE',
VER_NODE_PUBLIC: 'VER_NODE_PUBLIC',
VER_NODE_PRIVATE: 'VER_NODE_PRIVATE',
VER_ACCOUNT_ID: 'VER_ACCOUNT_ID',
VER_ACCOUNT_PUBLIC: 'VER_ACCOUNT_PUBLIC',
VER_ACCOUNT_PRIVATE: 'VER_ACCOUNT_PRIVATE',
VER_FAMILY_GENERATOR: 'VER_FAMILY_GENERATOR',
VER_FAMILY_SEED: 'VER_FAMILY_SEED'
}
class Alphabet(object):
def __init__(self, radix, digit_to_char, char_to_digit):
self.radix = radix
self.digit_to_char = digit_to_char
self.char_to_digit = char_to_digit
def transcode_from(self, s, source_alphabet):
n, zero_count = source_alphabet._digits_to_number(s)
digits = []
while n > 0:
n, digit = divmod(n, self.radix)
digits.append(self.digit_to_char(digit))
s = ''.join(digits)
return self.digit_to_char(0) * zero_count + s[::-1]
def _digits_to_number(self, digits):
stripped = digits.lstrip(self.digit_to_char(0))
n = 0
for d in stripped:
n *= self.radix
n += self.char_to_digit(d)
return n, len(digits) - len(stripped)
_INVERSE_INDEX = dict((c, i) for (i, c) in enumerate(ALPHABET))
# In base 58 encoding, the digits come from the ALPHABET string.
BASE58 = Alphabet(len(ALPHABET), ALPHABET.__getitem__, _INVERSE_INDEX.get)
# In base 256 encoding, each digit is just a character between 0 and 255.
BASE256 = Alphabet(256, chr, ord)
def encode(b):
return BASE58.transcode_from(b, BASE256)
def decode(b):
return BASE256.transcode_from(b, BASE58)
def checksum(b):
"""Returns a 4-byte checksum of a binary."""
return sha256(sha256(b).digest()).digest()[:4]
def encode_version(ver, b):
"""Encodes a version encoding and a binary as human string."""
b = chr(ver) + b
return encode(b + checksum(b))
def decode_version(s):
"""Decodes a human base-58 string into its version encoding and binary."""
b = decode(s)
body, check = b[:-4], b[-4:]
assert check == checksum(body), ('Bad checksum for', s)
return ord(body[0]), body[1:]
def version_name(ver):
return VERSION_NAME.get(ver) or ('(unknown version %s)' % ver)
def check_version(version, expected):
if version != expected:
raise ValueError('Expected version %s but got %s' % (
version_name(version), version_name(expected)))