Merge pull request #103 from CodeName393/Add-base58

Add Base58 Utils

unshackle/utils/base58.py

@@ -0,0 +1,137 @@
+# Clone from https://github.com/keis/base58
+
+"""Base58 encoding
+
+Implementations of Base58 and Base58Check encodings that are compatible
+with the bitcoin network.
+"""
+
+# This module is based upon base58 snippets found scattered over many bitcoin
+# tools written in python. From what I gather the original source is from a
+# forum post by Gavin Andresen, so direct your praise to him.
+# This module adds shiny packaging and support for python3.
+
+from functools import lru_cache
+from hashlib import sha256
+from typing import Mapping, Union
+
+__version__ = "2.1.1"
+
+# 58 character alphabet used
+BITCOIN_ALPHABET = b"123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
+RIPPLE_ALPHABET = b"rpshnaf39wBUDNEGHJKLM4PQRST7VWXYZ2bcdeCg65jkm8oFqi1tuvAxyz"
+XRP_ALPHABET = RIPPLE_ALPHABET
+
+# Retro compatibility
+alphabet = BITCOIN_ALPHABET
+
+
+def scrub_input(v: Union[str, bytes]) -> bytes:
+    if isinstance(v, str):
+        v = v.encode("ascii")
+
+    return v
+
+
+def b58encode_int(i: int, default_one: bool = True, alphabet: bytes = BITCOIN_ALPHABET) -> bytes:
+    """
+    Encode an integer using Base58
+    """
+    if not i and default_one:
+        return alphabet[0:1]
+    string = b""
+    base = len(alphabet)
+    while i:
+        i, idx = divmod(i, base)
+        string = alphabet[idx : idx + 1] + string
+    return string
+
+
+def b58encode(v: Union[str, bytes], alphabet: bytes = BITCOIN_ALPHABET) -> bytes:
+    """
+    Encode a string using Base58
+    """
+    v = scrub_input(v)
+
+    origlen = len(v)
+    v = v.lstrip(b"\0")
+    newlen = len(v)
+
+    acc = int.from_bytes(v, byteorder="big")  # first byte is most significant
+
+    result = b58encode_int(acc, default_one=False, alphabet=alphabet)
+    return alphabet[0:1] * (origlen - newlen) + result
+
+
+@lru_cache()
+def _get_base58_decode_map(alphabet: bytes, autofix: bool) -> Mapping[int, int]:
+    invmap = {char: index for index, char in enumerate(alphabet)}
+
+    if autofix:
+        groups = [b"0Oo", b"Il1"]
+        for group in groups:
+            pivots = [c for c in group if c in invmap]
+            if len(pivots) == 1:
+                for alternative in group:
+                    invmap[alternative] = invmap[pivots[0]]
+
+    return invmap
+
+
+def b58decode_int(v: Union[str, bytes], alphabet: bytes = BITCOIN_ALPHABET, *, autofix: bool = False) -> int:
+    """
+    Decode a Base58 encoded string as an integer
+    """
+    if b" " not in alphabet:
+        v = v.rstrip()
+    v = scrub_input(v)
+
+    map = _get_base58_decode_map(alphabet, autofix=autofix)
+
+    decimal = 0
+    base = len(alphabet)
+    try:
+        for char in v:
+            decimal = decimal * base + map[char]
+    except KeyError as e:
+        raise ValueError("Invalid character {!r}".format(chr(e.args[0]))) from None
+    return decimal
+
+
+def b58decode(v: Union[str, bytes], alphabet: bytes = BITCOIN_ALPHABET, *, autofix: bool = False) -> bytes:
+    """
+    Decode a Base58 encoded string
+    """
+    v = v.rstrip()
+    v = scrub_input(v)
+
+    origlen = len(v)
+    v = v.lstrip(alphabet[0:1])
+    newlen = len(v)
+
+    acc = b58decode_int(v, alphabet=alphabet, autofix=autofix)
+
+    return acc.to_bytes(origlen - newlen + (acc.bit_length() + 7) // 8, "big")
+
+
+def b58encode_check(v: Union[str, bytes], alphabet: bytes = BITCOIN_ALPHABET) -> bytes:
+    """
+    Encode a string using Base58 with a 4 character checksum
+    """
+    v = scrub_input(v)
+
+    digest = sha256(sha256(v).digest()).digest()
+    return b58encode(v + digest[:4], alphabet=alphabet)
+
+
+def b58decode_check(v: Union[str, bytes], alphabet: bytes = BITCOIN_ALPHABET, *, autofix: bool = False) -> bytes:
+    """Decode and verify the checksum of a Base58 encoded string"""
+
+    result = b58decode(v, alphabet=alphabet, autofix=autofix)
+    result, check = result[:-4], result[-4:]
+    digest = sha256(sha256(result).digest()).digest()
+
+    if check != digest[:4]:
+        raise ValueError("Invalid checksum")
+
+    return result