595 lines
20 KiB
Python
Executable file
595 lines
20 KiB
Python
Executable file
#! /usr/bin/env python3
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"""Base16, Base32, Base64 (RFC 3548), Base85 and Ascii85 data encodings"""
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# Modified 04-Oct-1995 by Jack Jansen to use binascii module
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# Modified 30-Dec-2003 by Barry Warsaw to add full RFC 3548 support
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# Modified 22-May-2007 by Guido van Rossum to use bytes everywhere
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import re
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import struct
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import binascii
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__all__ = [
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# Legacy interface exports traditional RFC 2045 Base64 encodings
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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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# Base85 and Ascii85 encodings
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'b85encode', 'b85decode', 'a85encode', 'a85decode',
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# Standard Base64 encoding
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'standard_b64encode', 'standard_b64decode',
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# Some common Base64 alternatives. As referenced by RFC 3458, see thread
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# starting at:
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#
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# http://zgp.org/pipermail/p2p-hackers/2001-September/000316.html
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'urlsafe_b64encode', 'urlsafe_b64decode',
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]
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bytes_types = (bytes, bytearray) # Types acceptable as binary data
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def _bytes_from_decode_data(s):
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if isinstance(s, str):
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try:
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return s.encode('ascii')
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except UnicodeEncodeError:
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raise ValueError('string argument should contain only ASCII characters')
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if isinstance(s, bytes_types):
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return s
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try:
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return memoryview(s).tobytes()
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except TypeError:
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raise TypeError("argument should be a bytes-like object or ASCII "
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"string, not %r" % s.__class__.__name__) from None
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# Base64 encoding/decoding uses binascii
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def b64encode(s, altchars=None):
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"""Encode the bytes-like object s using Base64 and return a bytes object.
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Optional altchars should be a byte string of length 2 which specifies an
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alternative alphabet for the '+' and '/' characters. This allows an
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application to e.g. generate url or filesystem safe Base64 strings.
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"""
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encoded = binascii.b2a_base64(s, newline=False)
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if altchars is not None:
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assert len(altchars) == 2, repr(altchars)
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return encoded.translate(bytes.maketrans(b'+/', altchars))
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return encoded
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def b64decode(s, altchars=None, validate=False):
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"""Decode the Base64 encoded bytes-like object or ASCII string s.
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Optional altchars must be a bytes-like object or ASCII string of length 2
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which specifies the alternative alphabet used instead of the '+' and '/'
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characters.
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The result is returned as a bytes object. A binascii.Error is raised if
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s is incorrectly padded.
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If validate is False (the default), characters that are neither in the
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normal base-64 alphabet nor the alternative alphabet are discarded prior
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to the padding check. If validate is True, these non-alphabet characters
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in the input result in a binascii.Error.
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"""
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s = _bytes_from_decode_data(s)
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if altchars is not None:
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altchars = _bytes_from_decode_data(altchars)
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assert len(altchars) == 2, repr(altchars)
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s = s.translate(bytes.maketrans(altchars, b'+/'))
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if validate and not re.match(b'^[A-Za-z0-9+/]*={0,2}$', s):
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raise binascii.Error('Non-base64 digit found')
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return binascii.a2b_base64(s)
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def standard_b64encode(s):
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"""Encode bytes-like object s using the standard Base64 alphabet.
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The result is returned as a bytes object.
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"""
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return b64encode(s)
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def standard_b64decode(s):
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"""Decode bytes encoded with the standard Base64 alphabet.
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Argument s is a bytes-like object or ASCII string to decode. The result
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is returned as a bytes object. A binascii.Error is raised if the input
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is incorrectly padded. Characters that are not in the standard alphabet
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are discarded prior to the padding check.
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"""
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return b64decode(s)
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_urlsafe_encode_translation = bytes.maketrans(b'+/', b'-_')
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_urlsafe_decode_translation = bytes.maketrans(b'-_', b'+/')
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def urlsafe_b64encode(s):
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"""Encode bytes using the URL- and filesystem-safe Base64 alphabet.
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Argument s is a bytes-like object to encode. The result is returned as a
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bytes object. The alphabet uses '-' instead of '+' and '_' instead of
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'/'.
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"""
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return b64encode(s).translate(_urlsafe_encode_translation)
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def urlsafe_b64decode(s):
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"""Decode bytes using the URL- and filesystem-safe Base64 alphabet.
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Argument s is a bytes-like object or ASCII string to decode. The result
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is returned as a bytes object. A binascii.Error is raised if the input
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is incorrectly padded. Characters that are not in the URL-safe base-64
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alphabet, and are not a plus '+' or slash '/', are discarded prior to the
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padding check.
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The alphabet uses '-' instead of '+' and '_' instead of '/'.
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"""
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s = _bytes_from_decode_data(s)
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s = s.translate(_urlsafe_decode_translation)
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return 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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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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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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b32tab = None
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if not isinstance(s, bytes_types):
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s = memoryview(s).tobytes()
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leftover = len(s) % 5
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# Pad the last quantum with zero bits if necessary
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if leftover:
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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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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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b32tab2[(c >> 20) & 0x3ff] + # bits 11 - 20
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b32tab2[(c >> 10) & 0x3ff] + # bits 21 - 30
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b32tab2[c & 0x3ff] # bits 31 - 40
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)
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# Adjust for any leftover partial quanta
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if leftover == 1:
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encoded[-6:] = b'======'
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elif leftover == 2:
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encoded[-4:] = b'===='
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elif leftover == 3:
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encoded[-3:] = b'==='
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elif leftover == 4:
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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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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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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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# Handle section 2.4 zero and one mapping. The flag map01 will be either
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# False, or the character to map the digit 1 (one) to. It should be
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# either L (el) or I (eye).
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if map01 is not None:
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map01 = _bytes_from_decode_data(map01)
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assert len(map01) == 1, repr(map01)
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s = s.translate(bytes.maketrans(b'01', b'O' + map01))
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if casefold:
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s = s.upper()
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# Strip off pad characters from the right. We need to count the pad
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# characters because this will tell us how many null bytes to remove from
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# the end of the decoded string.
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l = len(s)
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s = s.rstrip(b'=')
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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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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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try:
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for c in quanta:
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acc = (acc << 5) + b32rev[c]
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except KeyError:
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raise binascii.Error('Non-base32 digit found') from None
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decoded += acc.to_bytes(5, 'big')
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# Process the last, partial quanta
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if l % 8 or padchars not in {0, 1, 3, 4, 6}:
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raise binascii.Error('Incorrect padding')
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if padchars and decoded:
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acc <<= 5 * padchars
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last = acc.to_bytes(5, 'big')
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leftover = (43 - 5 * padchars) // 8 # 1: 4, 3: 3, 4: 2, 6: 1
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decoded[-5:] = last[:leftover]
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return bytes(decoded)
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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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def b16encode(s):
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"""Encode the bytes-like object s using Base16 and return a bytes object.
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"""
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return binascii.hexlify(s).upper()
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def b16decode(s, casefold=False):
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"""Decode the Base16 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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The result is returned as a bytes object. A binascii.Error is raised if
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s is incorrectly padded or if there are non-alphabet characters present
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in the input.
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"""
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s = _bytes_from_decode_data(s)
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if casefold:
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s = s.upper()
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if re.search(b'[^0-9A-F]', s):
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raise binascii.Error('Non-base16 digit found')
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return binascii.unhexlify(s)
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#
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# Ascii85 encoding/decoding
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#
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_a85chars = None
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_a85chars2 = None
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_A85START = b"<~"
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_A85END = b"~>"
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def _85encode(b, chars, chars2, pad=False, foldnuls=False, foldspaces=False):
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# Helper function for a85encode and b85encode
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if not isinstance(b, bytes_types):
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b = memoryview(b).tobytes()
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padding = (-len(b)) % 4
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if padding:
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b = b + b'\0' * padding
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words = struct.Struct('!%dI' % (len(b) // 4)).unpack(b)
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chunks = [b'z' if foldnuls and not word else
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b'y' if foldspaces and word == 0x20202020 else
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(chars2[word // 614125] +
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chars2[word // 85 % 7225] +
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chars[word % 85])
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for word in words]
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if padding and not pad:
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if chunks[-1] == b'z':
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chunks[-1] = chars[0] * 5
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chunks[-1] = chunks[-1][:-padding]
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return b''.join(chunks)
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def a85encode(b, *, foldspaces=False, wrapcol=0, pad=False, adobe=False):
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"""Encode bytes-like object b using Ascii85 and return a bytes object.
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foldspaces is an optional flag that uses the special short sequence 'y'
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instead of 4 consecutive spaces (ASCII 0x20) as supported by 'btoa'. This
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feature is not supported by the "standard" Adobe encoding.
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wrapcol controls whether the output should have newline (b'\\n') characters
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added to it. If this is non-zero, each output line will be at most this
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many characters long.
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pad controls whether the input is padded to a multiple of 4 before
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encoding. Note that the btoa implementation always pads.
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adobe controls whether the encoded byte sequence is framed with <~ and ~>,
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which is used by the Adobe implementation.
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"""
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global _a85chars, _a85chars2
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# Delay the initialization of tables to not waste memory
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# if the function is never called
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if _a85chars is None:
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_a85chars = [bytes((i,)) for i in range(33, 118)]
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_a85chars2 = [(a + b) for a in _a85chars for b in _a85chars]
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result = _85encode(b, _a85chars, _a85chars2, pad, True, foldspaces)
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if adobe:
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result = _A85START + result
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if wrapcol:
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wrapcol = max(2 if adobe else 1, wrapcol)
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chunks = [result[i: i + wrapcol]
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for i in range(0, len(result), wrapcol)]
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if adobe:
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if len(chunks[-1]) + 2 > wrapcol:
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chunks.append(b'')
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result = b'\n'.join(chunks)
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if adobe:
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result += _A85END
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return result
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def a85decode(b, *, foldspaces=False, adobe=False, ignorechars=b' \t\n\r\v'):
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"""Decode the Ascii85 encoded bytes-like object or ASCII string b.
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foldspaces is a flag that specifies whether the 'y' short sequence should be
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accepted as shorthand for 4 consecutive spaces (ASCII 0x20). This feature is
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not supported by the "standard" Adobe encoding.
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adobe controls whether the input sequence is in Adobe Ascii85 format (i.e.
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is framed with <~ and ~>).
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ignorechars should be a byte string containing characters to ignore from the
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input. This should only contain whitespace characters, and by default
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contains all whitespace characters in ASCII.
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The result is returned as a bytes object.
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"""
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b = _bytes_from_decode_data(b)
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if adobe:
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if not b.endswith(_A85END):
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raise ValueError(
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"Ascii85 encoded byte sequences must end "
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"with {!r}".format(_A85END)
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)
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if b.startswith(_A85START):
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b = b[2:-2] # Strip off start/end markers
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else:
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b = b[:-2]
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#
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# We have to go through this stepwise, so as to ignore spaces and handle
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# special short sequences
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#
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packI = struct.Struct('!I').pack
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decoded = []
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decoded_append = decoded.append
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curr = []
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curr_append = curr.append
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curr_clear = curr.clear
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for x in b + b'u' * 4:
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if b'!'[0] <= x <= b'u'[0]:
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curr_append(x)
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if len(curr) == 5:
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acc = 0
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for x in curr:
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acc = 85 * acc + (x - 33)
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try:
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decoded_append(packI(acc))
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except struct.error:
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raise ValueError('Ascii85 overflow') from None
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curr_clear()
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elif x == b'z'[0]:
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if curr:
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raise ValueError('z inside Ascii85 5-tuple')
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decoded_append(b'\0\0\0\0')
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elif foldspaces and x == b'y'[0]:
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if curr:
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raise ValueError('y inside Ascii85 5-tuple')
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decoded_append(b'\x20\x20\x20\x20')
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elif x in ignorechars:
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# Skip whitespace
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continue
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else:
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raise ValueError('Non-Ascii85 digit found: %c' % x)
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result = b''.join(decoded)
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padding = 4 - len(curr)
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if padding:
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# Throw away the extra padding
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result = result[:-padding]
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return result
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# The following code is originally taken (with permission) from Mercurial
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_b85alphabet = (b"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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b"abcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~")
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_b85chars = None
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_b85chars2 = None
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_b85dec = None
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def b85encode(b, pad=False):
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"""Encode bytes-like object b in base85 format and return a bytes object.
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If pad is true, the input is padded with b'\\0' so its length is a multiple of
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4 bytes before encoding.
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"""
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global _b85chars, _b85chars2
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# Delay the initialization of tables to not waste memory
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# if the function is never called
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if _b85chars is None:
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_b85chars = [bytes((i,)) for i in _b85alphabet]
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_b85chars2 = [(a + b) for a in _b85chars for b in _b85chars]
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return _85encode(b, _b85chars, _b85chars2, pad)
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def b85decode(b):
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"""Decode the base85-encoded bytes-like object or ASCII string b
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The result is returned as a bytes object.
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"""
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global _b85dec
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# Delay the initialization of tables to not waste memory
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# if the function is never called
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if _b85dec is None:
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_b85dec = [None] * 256
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for i, c in enumerate(_b85alphabet):
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_b85dec[c] = i
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b = _bytes_from_decode_data(b)
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padding = (-len(b)) % 5
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b = b + b'~' * padding
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out = []
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packI = struct.Struct('!I').pack
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for i in range(0, len(b), 5):
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chunk = b[i:i + 5]
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acc = 0
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try:
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for c in chunk:
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acc = acc * 85 + _b85dec[c]
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except TypeError:
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for j, c in enumerate(chunk):
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if _b85dec[c] is None:
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raise ValueError('bad base85 character at position %d'
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% (i + j)) from None
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raise
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try:
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out.append(packI(acc))
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except struct.error:
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raise ValueError('base85 overflow in hunk starting at byte %d'
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% i) from None
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result = b''.join(out)
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if padding:
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result = result[:-padding]
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return result
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# Legacy interface. This code could be cleaned up since I don't believe
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# binascii has any line length limitations. It just doesn't seem worth it
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# though. The files should be opened in binary mode.
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MAXLINESIZE = 76 # Excluding the CRLF
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MAXBINSIZE = (MAXLINESIZE//4)*3
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def encode(input, output):
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"""Encode a file; input and output are binary files."""
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while True:
|
|
s = input.read(MAXBINSIZE)
|
|
if not s:
|
|
break
|
|
while len(s) < MAXBINSIZE:
|
|
ns = input.read(MAXBINSIZE-len(s))
|
|
if not ns:
|
|
break
|
|
s += ns
|
|
line = binascii.b2a_base64(s)
|
|
output.write(line)
|
|
|
|
|
|
def decode(input, output):
|
|
"""Decode a file; input and output are binary files."""
|
|
while True:
|
|
line = input.readline()
|
|
if not line:
|
|
break
|
|
s = binascii.a2b_base64(line)
|
|
output.write(s)
|
|
|
|
def _input_type_check(s):
|
|
try:
|
|
m = memoryview(s)
|
|
except TypeError as err:
|
|
msg = "expected bytes-like object, not %s" % s.__class__.__name__
|
|
raise TypeError(msg) from err
|
|
if m.format not in ('c', 'b', 'B'):
|
|
msg = ("expected single byte elements, not %r from %s" %
|
|
(m.format, s.__class__.__name__))
|
|
raise TypeError(msg)
|
|
if m.ndim != 1:
|
|
msg = ("expected 1-D data, not %d-D data from %s" %
|
|
(m.ndim, s.__class__.__name__))
|
|
raise TypeError(msg)
|
|
|
|
|
|
def encodebytes(s):
|
|
"""Encode a bytestring into a bytes object containing multiple lines
|
|
of base-64 data."""
|
|
_input_type_check(s)
|
|
pieces = []
|
|
for i in range(0, len(s), MAXBINSIZE):
|
|
chunk = s[i : i + MAXBINSIZE]
|
|
pieces.append(binascii.b2a_base64(chunk))
|
|
return b"".join(pieces)
|
|
|
|
def encodestring(s):
|
|
"""Legacy alias of encodebytes()."""
|
|
import warnings
|
|
warnings.warn("encodestring() is a deprecated alias since 3.1, "
|
|
"use encodebytes()",
|
|
DeprecationWarning, 2)
|
|
return encodebytes(s)
|
|
|
|
|
|
def decodebytes(s):
|
|
"""Decode a bytestring of base-64 data into a bytes object."""
|
|
_input_type_check(s)
|
|
return binascii.a2b_base64(s)
|
|
|
|
def decodestring(s):
|
|
"""Legacy alias of decodebytes()."""
|
|
import warnings
|
|
warnings.warn("decodestring() is a deprecated alias since Python 3.1, "
|
|
"use decodebytes()",
|
|
DeprecationWarning, 2)
|
|
return decodebytes(s)
|
|
|
|
|
|
# Usable as a script...
|
|
def main():
|
|
"""Small main program"""
|
|
import sys, getopt
|
|
try:
|
|
opts, args = getopt.getopt(sys.argv[1:], 'deut')
|
|
except getopt.error as msg:
|
|
sys.stdout = sys.stderr
|
|
print(msg)
|
|
print("""usage: %s [-d|-e|-u|-t] [file|-]
|
|
-d, -u: decode
|
|
-e: encode (default)
|
|
-t: encode and decode string 'Aladdin:open sesame'"""%sys.argv[0])
|
|
sys.exit(2)
|
|
func = encode
|
|
for o, a in opts:
|
|
if o == '-e': func = encode
|
|
if o == '-d': func = decode
|
|
if o == '-u': func = decode
|
|
if o == '-t': test(); return
|
|
if args and args[0] != '-':
|
|
with open(args[0], 'rb') as f:
|
|
func(f, sys.stdout.buffer)
|
|
else:
|
|
func(sys.stdin.buffer, sys.stdout.buffer)
|
|
|
|
|
|
def test():
|
|
s0 = b"Aladdin:open sesame"
|
|
print(repr(s0))
|
|
s1 = encodebytes(s0)
|
|
print(repr(s1))
|
|
s2 = decodebytes(s1)
|
|
print(repr(s2))
|
|
assert s0 == s2
|
|
|
|
|
|
if __name__ == '__main__':
|
|
main()
|