From 4ce6faa6c9591de6079347eccc9e61ae4e8d9e31 Mon Sep 17 00:00:00 2001 From: Filipe Laíns Date: Mon, 10 Aug 2020 15:48:20 +0100 Subject: bpo-16995: add support for base32 extended hex (base32hex) (GH-20441) cc @pganssle Automerge-Triggered-By: @pganssle --- Lib/base64.py | 86 ++++++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 55 insertions(+), 31 deletions(-) (limited to 'Lib/base64.py') diff --git a/Lib/base64.py b/Lib/base64.py index a28109f8a7f..539ad16f0e8 100755 --- a/Lib/base64.py +++ b/Lib/base64.py @@ -16,7 +16,7 @@ __all__ = [ 'encode', 'decode', 'encodebytes', 'decodebytes', # Generalized interface for other encodings 'b64encode', 'b64decode', 'b32encode', 'b32decode', - 'b16encode', 'b16decode', + 'b32hexencode', 'b32hexdecode', 'b16encode', 'b16decode', # Base85 and Ascii85 encodings 'b85encode', 'b85decode', 'a85encode', 'a85decode', # Standard Base64 encoding @@ -135,19 +135,40 @@ def urlsafe_b64decode(s): # Base32 encoding/decoding must be done in Python +_B32_ENCODE_DOCSTRING = ''' +Encode the bytes-like objects using {encoding} and return a bytes object. +''' +_B32_DECODE_DOCSTRING = ''' +Decode the {encoding} encoded bytes-like object or ASCII string s. + +Optional casefold is a flag specifying whether a lowercase alphabet is +acceptable as input. For security purposes, the default is False. +{extra_args} +The result is returned as a bytes object. A binascii.Error is raised if +the input is incorrectly padded or if there are non-alphabet +characters present in the input. +''' +_B32_DECODE_MAP01_DOCSTRING = ''' +RFC 3548 allows for optional mapping of the digit 0 (zero) to the +letter O (oh), and for optional mapping of the digit 1 (one) to +either the letter I (eye) or letter L (el). The optional argument +map01 when not None, specifies which letter the digit 1 should be +mapped to (when map01 is not None, the digit 0 is always mapped to +the letter O). For security purposes the default is None, so that +0 and 1 are not allowed in the input. +''' _b32alphabet = b'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567' -_b32tab2 = None -_b32rev = None +_b32hexalphabet = b'0123456789ABCDEFGHIJKLMNOPQRSTUV' +_b32tab2 = {} +_b32rev = {} -def b32encode(s): - """Encode the bytes-like object s using Base32 and return a bytes object. - """ +def _b32encode(alphabet, s): global _b32tab2 # Delay the initialization of the table to not waste memory # if the function is never called - if _b32tab2 is None: - b32tab = [bytes((i,)) for i in _b32alphabet] - _b32tab2 = [a + b for a in b32tab for b in b32tab] + if alphabet not in _b32tab2: + b32tab = [bytes((i,)) for i in alphabet] + _b32tab2[alphabet] = [a + b for a in b32tab for b in b32tab] b32tab = None if not isinstance(s, bytes_types): @@ -158,7 +179,7 @@ def b32encode(s): s = s + b'\0' * (5 - leftover) # Don't use += ! encoded = bytearray() from_bytes = int.from_bytes - b32tab2 = _b32tab2 + b32tab2 = _b32tab2[alphabet] for i in range(0, len(s), 5): c = from_bytes(s[i: i + 5], 'big') encoded += (b32tab2[c >> 30] + # bits 1 - 10 @@ -177,29 +198,12 @@ def b32encode(s): encoded[-1:] = b'=' return bytes(encoded) -def b32decode(s, casefold=False, map01=None): - """Decode the Base32 encoded bytes-like object or ASCII string s. - - Optional casefold is a flag specifying whether a lowercase alphabet is - acceptable as input. For security purposes, the default is False. - - RFC 3548 allows for optional mapping of the digit 0 (zero) to the - letter O (oh), and for optional mapping of the digit 1 (one) to - either the letter I (eye) or letter L (el). The optional argument - map01 when not None, specifies which letter the digit 1 should be - mapped to (when map01 is not None, the digit 0 is always mapped to - the letter O). For security purposes the default is None, so that - 0 and 1 are not allowed in the input. - - The result is returned as a bytes object. A binascii.Error is raised if - the input is incorrectly padded or if there are non-alphabet - characters present in the input. - """ +def _b32decode(alphabet, s, casefold=False, map01=None): global _b32rev # Delay the initialization of the table to not waste memory # if the function is never called - if _b32rev is None: - _b32rev = {v: k for k, v in enumerate(_b32alphabet)} + if alphabet not in _b32rev: + _b32rev[alphabet] = {v: k for k, v in enumerate(alphabet)} s = _bytes_from_decode_data(s) if len(s) % 8: raise binascii.Error('Incorrect padding') @@ -220,7 +224,7 @@ def b32decode(s, casefold=False, map01=None): padchars = l - len(s) # Now decode the full quanta decoded = bytearray() - b32rev = _b32rev + b32rev = _b32rev[alphabet] for i in range(0, len(s), 8): quanta = s[i: i + 8] acc = 0 @@ -241,6 +245,26 @@ def b32decode(s, casefold=False, map01=None): return bytes(decoded) +def b32encode(s): + return _b32encode(_b32alphabet, s) +b32encode.__doc__ = _B32_ENCODE_DOCSTRING.format(encoding='base32') + +def b32decode(s, casefold=False, map01=None): + return _b32decode(_b32alphabet, s, casefold, map01) +b32decode.__doc__ = _B32_DECODE_DOCSTRING.format(encoding='base32', + extra_args=_B32_DECODE_MAP01_DOCSTRING) + +def b32hexencode(s): + return _b32encode(_b32hexalphabet, s) +b32hexencode.__doc__ = _B32_ENCODE_DOCSTRING.format(encoding='base32hex') + +def b32hexdecode(s, casefold=False): + # base32hex does not have the 01 mapping + return _b32decode(_b32hexalphabet, s, casefold) +b32hexdecode.__doc__ = _B32_DECODE_DOCSTRING.format(encoding='base32hex', + extra_args='') + + # RFC 3548, Base 16 Alphabet specifies uppercase, but hexlify() returns # lowercase. The RFC also recommends against accepting input case # insensitively. -- cgit v1.2.3