bpo-16995: add support for base32 extended hex (base32hex) (GH-20441)
cc @pganssle Automerge-Triggered-By: @pganssle
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@ -124,7 +124,7 @@ The modern interface provides:
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whether a lowercase alphabet is acceptable as input. For security purposes,
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the default is ``False``.
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:rfc:`3548` allows for optional mapping of the digit 0 (zero) to the letter O
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:rfc:`4648` allows for optional mapping of the digit 0 (zero) to the letter O
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(oh), and for optional mapping of the digit 1 (one) to either the letter I (eye)
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or letter L (el). The optional argument *map01* when not ``None``, specifies
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which letter the digit 1 should be mapped to (when *map01* is not ``None``, the
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@ -136,6 +136,27 @@ The modern interface provides:
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input.
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.. function:: b32hexencode(s)
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Similar to :func:`b32encode` but uses the Extended Hex Alphabet, as defined in
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:rfc:`4648`.
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.. versionadded:: 3.10
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.. function:: b32hexdecode(s, casefold=False)
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Similar to :func:`b32decode` but uses the Extended Hex Alphabet, as defined in
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:rfc:`4648`.
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This version does not allow the digit 0 (zero) to the letter O (oh) and digit
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1 (one) to either the letter I (eye) or letter L (el) mappings, all these
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characters are included in the Extended Hex Alphabet and are not
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interchangable.
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.. versionadded:: 3.10
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.. function:: b16encode(s)
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Encode the :term:`bytes-like object` *s* using Base16 and return the
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@ -103,6 +103,12 @@ New Modules
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Improved Modules
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================
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base64
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------
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Add :func:`base64.b32hexencode` and :func:`base64.b32hexdecode` to support the
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Base32 Encoding with Extended Hex Alphabet.
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curses
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------
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@ -16,7 +16,7 @@ __all__ = [
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'encode', 'decode', 'encodebytes', 'decodebytes',
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# Generalized interface for other encodings
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'b64encode', 'b64decode', 'b32encode', 'b32decode',
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'b16encode', 'b16decode',
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'b32hexencode', 'b32hexdecode', 'b16encode', 'b16decode',
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# Base85 and Ascii85 encodings
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'b85encode', 'b85decode', 'a85encode', 'a85decode',
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# Standard Base64 encoding
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@ -135,19 +135,40 @@ def urlsafe_b64decode(s):
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# Base32 encoding/decoding must be done in Python
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_b32alphabet = b'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567'
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_b32tab2 = None
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_b32rev = None
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_B32_ENCODE_DOCSTRING = '''
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Encode the bytes-like objects using {encoding} and return a bytes object.
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'''
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_B32_DECODE_DOCSTRING = '''
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Decode the {encoding} encoded bytes-like object or ASCII string s.
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def b32encode(s):
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"""Encode the bytes-like object s using Base32 and return a bytes object.
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"""
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Optional casefold is a flag specifying whether a lowercase alphabet is
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acceptable as input. For security purposes, the default is False.
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{extra_args}
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The result is returned as a bytes object. A binascii.Error is raised if
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the input is incorrectly padded or if there are non-alphabet
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characters present in the input.
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'''
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_B32_DECODE_MAP01_DOCSTRING = '''
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RFC 3548 allows for optional mapping of the digit 0 (zero) to the
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letter O (oh), and for optional mapping of the digit 1 (one) to
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either the letter I (eye) or letter L (el). The optional argument
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map01 when not None, specifies which letter the digit 1 should be
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mapped to (when map01 is not None, the digit 0 is always mapped to
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the letter O). For security purposes the default is None, so that
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0 and 1 are not allowed in the input.
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'''
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_b32alphabet = b'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567'
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_b32hexalphabet = b'0123456789ABCDEFGHIJKLMNOPQRSTUV'
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_b32tab2 = {}
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_b32rev = {}
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def _b32encode(alphabet, s):
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global _b32tab2
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# Delay the initialization of the table to not waste memory
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# if the function is never called
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if _b32tab2 is None:
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b32tab = [bytes((i,)) for i in _b32alphabet]
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_b32tab2 = [a + b for a in b32tab for b in b32tab]
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if alphabet not in _b32tab2:
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b32tab = [bytes((i,)) for i in alphabet]
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_b32tab2[alphabet] = [a + b for a in b32tab for b in b32tab]
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b32tab = None
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if not isinstance(s, bytes_types):
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@ -158,7 +179,7 @@ def b32encode(s):
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s = s + b'\0' * (5 - leftover) # Don't use += !
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encoded = bytearray()
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from_bytes = int.from_bytes
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b32tab2 = _b32tab2
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b32tab2 = _b32tab2[alphabet]
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for i in range(0, len(s), 5):
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c = from_bytes(s[i: i + 5], 'big')
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encoded += (b32tab2[c >> 30] + # bits 1 - 10
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@ -177,29 +198,12 @@ def b32encode(s):
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encoded[-1:] = b'='
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return bytes(encoded)
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def b32decode(s, casefold=False, map01=None):
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"""Decode the Base32 encoded bytes-like object or ASCII string s.
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Optional casefold is a flag specifying whether a lowercase alphabet is
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acceptable as input. For security purposes, the default is False.
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RFC 3548 allows for optional mapping of the digit 0 (zero) to the
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letter O (oh), and for optional mapping of the digit 1 (one) to
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either the letter I (eye) or letter L (el). The optional argument
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map01 when not None, specifies which letter the digit 1 should be
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mapped to (when map01 is not None, the digit 0 is always mapped to
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the letter O). For security purposes the default is None, so that
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0 and 1 are not allowed in the input.
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The result is returned as a bytes object. A binascii.Error is raised if
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the input is incorrectly padded or if there are non-alphabet
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characters present in the input.
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"""
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def _b32decode(alphabet, s, casefold=False, map01=None):
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global _b32rev
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# Delay the initialization of the table to not waste memory
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# if the function is never called
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if _b32rev is None:
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_b32rev = {v: k for k, v in enumerate(_b32alphabet)}
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if alphabet not in _b32rev:
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_b32rev[alphabet] = {v: k for k, v in enumerate(alphabet)}
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s = _bytes_from_decode_data(s)
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if len(s) % 8:
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raise binascii.Error('Incorrect padding')
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@ -220,7 +224,7 @@ def b32decode(s, casefold=False, map01=None):
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padchars = l - len(s)
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# Now decode the full quanta
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decoded = bytearray()
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b32rev = _b32rev
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b32rev = _b32rev[alphabet]
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for i in range(0, len(s), 8):
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quanta = s[i: i + 8]
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acc = 0
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@ -241,6 +245,26 @@ def b32decode(s, casefold=False, map01=None):
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return bytes(decoded)
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def b32encode(s):
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return _b32encode(_b32alphabet, s)
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b32encode.__doc__ = _B32_ENCODE_DOCSTRING.format(encoding='base32')
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def b32decode(s, casefold=False, map01=None):
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return _b32decode(_b32alphabet, s, casefold, map01)
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b32decode.__doc__ = _B32_DECODE_DOCSTRING.format(encoding='base32',
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extra_args=_B32_DECODE_MAP01_DOCSTRING)
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def b32hexencode(s):
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return _b32encode(_b32hexalphabet, s)
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b32hexencode.__doc__ = _B32_ENCODE_DOCSTRING.format(encoding='base32hex')
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def b32hexdecode(s, casefold=False):
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# base32hex does not have the 01 mapping
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return _b32decode(_b32hexalphabet, s, casefold)
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b32hexdecode.__doc__ = _B32_DECODE_DOCSTRING.format(encoding='base32hex',
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extra_args='')
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# RFC 3548, Base 16 Alphabet specifies uppercase, but hexlify() returns
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# lowercase. The RFC also recommends against accepting input case
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# insensitively.
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@ -351,6 +351,76 @@ class BaseXYTestCase(unittest.TestCase):
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with self.assertRaises(binascii.Error):
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base64.b32decode(data.decode('ascii'))
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def test_b32hexencode(self):
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test_cases = [
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# to_encode, expected
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(b'', b''),
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(b'\x00', b'00======'),
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(b'a', b'C4======'),
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(b'ab', b'C5H0===='),
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(b'abc', b'C5H66==='),
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(b'abcd', b'C5H66P0='),
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(b'abcde', b'C5H66P35'),
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]
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for to_encode, expected in test_cases:
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with self.subTest(to_decode=to_encode):
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self.assertEqual(base64.b32hexencode(to_encode), expected)
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def test_b32hexencode_other_types(self):
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self.check_other_types(base64.b32hexencode, b'abcd', b'C5H66P0=')
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self.check_encode_type_errors(base64.b32hexencode)
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def test_b32hexdecode(self):
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test_cases = [
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# to_decode, expected, casefold
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(b'', b'', False),
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(b'00======', b'\x00', False),
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(b'C4======', b'a', False),
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(b'C5H0====', b'ab', False),
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(b'C5H66===', b'abc', False),
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(b'C5H66P0=', b'abcd', False),
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(b'C5H66P35', b'abcde', False),
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(b'', b'', True),
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(b'00======', b'\x00', True),
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(b'C4======', b'a', True),
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(b'C5H0====', b'ab', True),
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(b'C5H66===', b'abc', True),
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(b'C5H66P0=', b'abcd', True),
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(b'C5H66P35', b'abcde', True),
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(b'c4======', b'a', True),
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(b'c5h0====', b'ab', True),
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(b'c5h66===', b'abc', True),
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(b'c5h66p0=', b'abcd', True),
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(b'c5h66p35', b'abcde', True),
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]
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for to_decode, expected, casefold in test_cases:
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with self.subTest(to_decode=to_decode, casefold=casefold):
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self.assertEqual(base64.b32hexdecode(to_decode, casefold),
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expected)
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self.assertEqual(base64.b32hexdecode(to_decode.decode('ascii'),
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casefold), expected)
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def test_b32hexdecode_other_types(self):
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self.check_other_types(base64.b32hexdecode, b'C5H66===', b'abc')
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self.check_decode_type_errors(base64.b32hexdecode)
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def test_b32hexdecode_error(self):
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tests = [b'abc', b'ABCDEF==', b'==ABCDEF', b'c4======']
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prefixes = [b'M', b'ME', b'MFRA', b'MFRGG', b'MFRGGZA', b'MFRGGZDF']
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for i in range(0, 17):
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if i:
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tests.append(b'='*i)
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for prefix in prefixes:
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if len(prefix) + i != 8:
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tests.append(prefix + b'='*i)
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for data in tests:
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with self.subTest(to_decode=data):
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with self.assertRaises(binascii.Error):
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base64.b32hexdecode(data)
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with self.assertRaises(binascii.Error):
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base64.b32hexdecode(data.decode('ascii'))
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def test_b16encode(self):
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eq = self.assertEqual
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eq(base64.b16encode(b'\x01\x02\xab\xcd\xef'), b'0102ABCDEF')
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@ -0,0 +1,2 @@
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Add :func:`base64.b32hexencode` and :func:`base64.b32hexdecode` to support the
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Base32 Encoding with Extended Hex Alphabet.
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