"""Base16, Base32, Base64 (RFC 3548), Base85 and Ascii85 data encodings""" # Modified 04-Oct-1995 by Jack Jansen to use binascii module # Modified 30-Dec-2003 by Barry Warsaw to add full RFC 3548 support # Modified 22-May-2007 by Guido van Rossum to use bytes everywhere import struct import binascii __all__ = [ # Legacy interface exports traditional RFC 2045 Base64 encodings 'encode', 'decode', 'encodebytes', 'decodebytes', # Generalized interface for other encodings 'b64encode', 'b64decode', 'b32encode', 'b32decode', 'b32hexencode', 'b32hexdecode', 'b16encode', 'b16decode', # Base85 and Ascii85 encodings 'b85encode', 'b85decode', 'a85encode', 'a85decode', 'z85encode', 'z85decode', # Standard Base64 encoding 'standard_b64encode', 'standard_b64decode', # Some common Base64 alternatives. As referenced by RFC 3458, see thread # starting at: # # http://zgp.org/pipermail/p2p-hackers/2001-September/000316.html 'urlsafe_b64encode', 'urlsafe_b64decode', ] bytes_types = (bytes, bytearray) # Types acceptable as binary data def _bytes_from_decode_data(s): if isinstance(s, str): try: return s.encode('ascii') except UnicodeEncodeError: raise ValueError('string argument should contain only ASCII characters') if isinstance(s, bytes_types): return s try: return memoryview(s).tobytes() except TypeError: raise TypeError("argument should be a bytes-like object or ASCII " "string, not %r" % s.__class__.__name__) from None # Base64 encoding/decoding uses binascii def b64encode(s, altchars=None): """Encode the bytes-like object s using Base64 and return a bytes object. Optional altchars should be a byte string of length 2 which specifies an alternative alphabet for the '+' and '/' characters. This allows an application to e.g. generate url or filesystem safe Base64 strings. """ encoded = binascii.b2a_base64(s, newline=False) if altchars is not None: assert len(altchars) == 2, repr(altchars) return encoded.translate(bytes.maketrans(b'+/', altchars)) return encoded def b64decode(s, altchars=None, validate=False): """Decode the Base64 encoded bytes-like object or ASCII string s. Optional altchars must be a bytes-like object or ASCII string of length 2 which specifies the alternative alphabet used instead of the '+' and '/' characters. The result is returned as a bytes object. A binascii.Error is raised if s is incorrectly padded. If validate is False (the default), characters that are neither in the normal base-64 alphabet nor the alternative alphabet are discarded prior to the padding check. If validate is True, these non-alphabet characters in the input result in a binascii.Error. For more information about the strict base64 check, see: https://docs.python.org/3.11/library/binascii.html#binascii.a2b_base64 """ s = _bytes_from_decode_data(s) if altchars is not None: altchars = _bytes_from_decode_data(altchars) assert len(altchars) == 2, repr(altchars) s = s.translate(bytes.maketrans(altchars, b'+/')) return binascii.a2b_base64(s, strict_mode=validate) def standard_b64encode(s): """Encode bytes-like object s using the standard Base64 alphabet. The result is returned as a bytes object. """ return b64encode(s) def standard_b64decode(s): """Decode bytes encoded with the standard Base64 alphabet. Argument s is a bytes-like object or ASCII string to decode. The result is returned as a bytes object. A binascii.Error is raised if the input is incorrectly padded. Characters that are not in the standard alphabet are discarded prior to the padding check. """ return b64decode(s) _urlsafe_encode_translation = bytes.maketrans(b'+/', b'-_') _urlsafe_decode_translation = bytes.maketrans(b'-_', b'+/') def urlsafe_b64encode(s): """Encode bytes using the URL- and filesystem-safe Base64 alphabet. Argument s is a bytes-like object to encode. The result is returned as a bytes object. The alphabet uses '-' instead of '+' and '_' instead of '/'. """ return b64encode(s).translate(_urlsafe_encode_translation) def urlsafe_b64decode(s): """Decode bytes using the URL- and filesystem-safe Base64 alphabet. Argument s is a bytes-like object or ASCII string to decode. The result is returned as a bytes object. A binascii.Error is raised if the input is incorrectly padded. Characters that are not in the URL-safe base-64 alphabet, and are not a plus '+' or slash '/', are discarded prior to the padding check. The alphabet uses '-' instead of '+' and '_' instead of '/'. """ s = _bytes_from_decode_data(s) s = s.translate(_urlsafe_decode_translation) return 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' _b32hexalphabet = b'0123456789ABCDEFGHIJKLMNOPQRSTUV' _b32tab2 = {} _b32rev = {} def _b32encode(alphabet, s): # Delay the initialization of the table to not waste memory # if the function is never called 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): s = memoryview(s).tobytes() leftover = len(s) % 5 # Pad the last quantum with zero bits if necessary if leftover: s = s + b'\0' * (5 - leftover) # Don't use += ! encoded = bytearray() from_bytes = int.from_bytes b32tab2 = _b32tab2[alphabet] for i in range(0, len(s), 5): c = from_bytes(s[i: i + 5]) # big endian encoded += (b32tab2[c >> 30] + # bits 1 - 10 b32tab2[(c >> 20) & 0x3ff] + # bits 11 - 20 b32tab2[(c >> 10) & 0x3ff] + # bits 21 - 30 b32tab2[c & 0x3ff] # bits 31 - 40 ) # Adjust for any leftover partial quanta if leftover == 1: encoded[-6:] = b'======' elif leftover == 2: encoded[-4:] = b'====' elif leftover == 3: encoded[-3:] = b'===' elif leftover == 4: encoded[-1:] = b'=' return bytes(encoded) def _b32decode(alphabet, s, casefold=False, map01=None): # Delay the initialization of the table to not waste memory # if the function is never called 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') # Handle section 2.4 zero and one mapping. The flag map01 will be either # False, or the character to map the digit 1 (one) to. It should be # either L (el) or I (eye). if map01 is not None: map01 = _bytes_from_decode_data(map01) assert len(map01) == 1, repr(map01) s = s.translate(bytes.maketrans(b'01', b'O' + map01)) if casefold: s = s.upper() # Strip off pad characters from the right. We need to count the pad # characters because this will tell us how many null bytes to remove from # the end of the decoded string. l = len(s) s = s.rstrip(b'=') padchars = l - len(s) # Now decode the full quanta decoded = bytearray() b32rev = _b32rev[alphabet] for i in range(0, len(s), 8): quanta = s[i: i + 8] acc = 0 try: for c in quanta: acc = (acc << 5) + b32rev[c] except KeyError: raise binascii.Error('Non-base32 digit found') from None decoded += acc.to_bytes(5) # big endian # Process the last, partial quanta if l % 8 or padchars not in {0, 1, 3, 4, 6}: raise binascii.Error('Incorrect padding') if padchars and decoded: acc <<= 5 * padchars last = acc.to_bytes(5) # big endian leftover = (43 - 5 * padchars) // 8 # 1: 4, 3: 3, 4: 2, 6: 1 decoded[-5:] = last[:leftover] 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. def b16encode(s): """Encode the bytes-like object s using Base16 and return a bytes object. """ return binascii.hexlify(s).upper() def b16decode(s, casefold=False): """Decode the Base16 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. The result is returned as a bytes object. A binascii.Error is raised if s is incorrectly padded or if there are non-alphabet characters present in the input. """ s = _bytes_from_decode_data(s) if casefold: s = s.upper() if s.translate(None, delete=b'0123456789ABCDEF'): raise binascii.Error('Non-base16 digit found') return binascii.unhexlify(s) # # Ascii85 encoding/decoding # _a85chars = None _a85chars2 = None _A85START = b"<~" _A85END = b"~>" def _85encode(b, chars, chars2, pad=False, foldnuls=False, foldspaces=False): # Helper function for a85encode and b85encode if not isinstance(b, bytes_types): b = memoryview(b).tobytes() padding = (-len(b)) % 4 if padding: b = b + b'\0' * padding words = struct.Struct('!%dI' % (len(b) // 4)).unpack(b) chunks = [b'z' if foldnuls and not word else b'y' if foldspaces and word == 0x20202020 else (chars2[word // 614125] + chars2[word // 85 % 7225] + chars[word % 85]) for word in words] if padding and not pad: if chunks[-1] == b'z': chunks[-1] = chars[0] * 5 chunks[-1] = chunks[-1][:-padding] return b''.join(chunks) def a85encode(b, *, foldspaces=False, wrapcol=0, pad=False, adobe=False): """Encode bytes-like object b using Ascii85 and return a bytes object. foldspaces is an optional flag that uses the special short sequence 'y' instead of 4 consecutive spaces (ASCII 0x20) as supported by 'btoa'. This feature is not supported by the standard encoding used in PDF. If wrapcol is non-zero, insert a newline (b'\\n') character after at most every wrapcol characters. pad controls whether zero-padding applied to the end of the input is fully retained in the output encoding, as done by btoa, producing an exact multiple of 5 bytes of output. adobe controls whether the encoded byte sequence is framed with <~ and ~>, as in a PostScript base-85 string literal. Note that while ASCII85Decode streams in PDF documents must be terminated with ~>, they must not use a leading <~. """ global _a85chars, _a85chars2 # Delay the initialization of tables to not waste memory # if the function is never called if _a85chars2 is None: _a85chars = [bytes((i,)) for i in range(33, 118)] _a85chars2 = [(a + b) for a in _a85chars for b in _a85chars] result = _85encode(b, _a85chars, _a85chars2, pad, True, foldspaces) if adobe: result = _A85START + result if wrapcol: wrapcol = max(2 if adobe else 1, wrapcol) chunks = [result[i: i + wrapcol] for i in range(0, len(result), wrapcol)] if adobe: if len(chunks[-1]) + 2 > wrapcol: chunks.append(b'') result = b'\n'.join(chunks) if adobe: result += _A85END return result def a85decode(b, *, foldspaces=False, adobe=False, ignorechars=b' \t\n\r\v'): """Decode the Ascii85 encoded bytes-like object or ASCII string b. foldspaces is a flag that specifies whether the 'y' short sequence should be accepted as shorthand for 4 consecutive spaces (ASCII 0x20). This feature is not supported by the standard Ascii85 encoding used in PDF and PostScript. adobe controls whether the <~ and ~> markers are present. While the leading <~ is not required, the input must end with ~>, or a ValueError is raised. ignorechars should be a byte string containing characters to ignore from the input. This should only contain whitespace characters, and by default contains all whitespace characters in ASCII. The result is returned as a bytes object. """ b = _bytes_from_decode_data(b) if adobe: if not b.endswith(_A85END): raise ValueError( "Ascii85 encoded byte sequences must end " "with {!r}".format(_A85END) ) if b.startswith(_A85START): b = b[2:-2] # Strip off start/end markers else: b = b[:-2] # # We have to go through this stepwise, so as to ignore spaces and handle # special short sequences # packI = struct.Struct('!I').pack decoded = [] decoded_append = decoded.append curr = [] curr_append = curr.append curr_clear = curr.clear for x in b + b'u' * 4: if b'!'[0] <= x <= b'u'[0]: curr_append(x) if len(curr) == 5: acc = 0 for x in curr: acc = 85 * acc + (x - 33) try: decoded_append(packI(acc)) except struct.error: raise ValueError('Ascii85 overflow') from None curr_clear() elif x == b'z'[0]: if curr: raise ValueError('z inside Ascii85 5-tuple') decoded_append(b'\0\0\0\0') elif foldspaces and x == b'y'[0]: if curr: raise ValueError('y inside Ascii85 5-tuple') decoded_append(b'\x20\x20\x20\x20') elif x in ignorechars: # Skip whitespace continue else: raise ValueError('Non-Ascii85 digit found: %c' % x) result = b''.join(decoded) padding = 4 - len(curr) if padding: # Throw away the extra padding result = result[:-padding] return result # The following code is originally taken (with permission) from Mercurial _b85alphabet = (b"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" b"abcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~") _b85chars = None _b85chars2 = None _b85dec = None def b85encode(b, pad=False): """Encode bytes-like object b in base85 format and return a bytes object. The input is padded with b'\0' so its length is a multiple of 4 bytes before encoding. If pad is true, all the resulting characters are retained in the output, which will always be a multiple of 5 bytes. """ global _b85chars, _b85chars2 # Delay the initialization of tables to not waste memory # if the function is never called if _b85chars2 is None: _b85chars = [bytes((i,)) for i in _b85alphabet] _b85chars2 = [(a + b) for a in _b85chars for b in _b85chars] return _85encode(b, _b85chars, _b85chars2, pad) def b85decode(b): """Decode the base85-encoded bytes-like object or ASCII string b The result is returned as a bytes object. """ global _b85dec # Delay the initialization of tables to not waste memory # if the function is never called if _b85dec is None: # we don't assign to _b85dec directly to avoid issues when # multiple threads call this function simultaneously b85dec_tmp = [None] * 256 for i, c in enumerate(_b85alphabet): b85dec_tmp[c] = i _b85dec = b85dec_tmp b = _bytes_from_decode_data(b) padding = (-len(b)) % 5 b = b + b'~' * padding out = [] packI = struct.Struct('!I').pack for i in range(0, len(b), 5): chunk = b[i:i + 5] acc = 0 try: for c in chunk: acc = acc * 85 + _b85dec[c] except TypeError: for j, c in enumerate(chunk): if _b85dec[c] is None: raise ValueError('bad base85 character at position %d' % (i + j)) from None raise try: out.append(packI(acc)) except struct.error: raise ValueError('base85 overflow in hunk starting at byte %d' % i) from None result = b''.join(out) if padding: result = result[:-padding] return result _z85alphabet = (b'0123456789abcdefghijklmnopqrstuvwxyz' b'ABCDEFGHIJKLMNOPQRSTUVWXYZ.-:+=^!/*?&<>()[]{}@%$#') # Translating b85 valid but z85 invalid chars to b'\x00' is required # to prevent them from being decoded as b85 valid chars. _z85_b85_decode_diff = b';_`|~' _z85_decode_translation = bytes.maketrans( _z85alphabet + _z85_b85_decode_diff, _b85alphabet + b'\x00' * len(_z85_b85_decode_diff) ) _z85_encode_translation = bytes.maketrans(_b85alphabet, _z85alphabet) def z85encode(s): """Encode bytes-like object b in z85 format and return a bytes object.""" return b85encode(s).translate(_z85_encode_translation) def z85decode(s): """Decode the z85-encoded bytes-like object or ASCII string b The result is returned as a bytes object. """ s = _bytes_from_decode_data(s) s = s.translate(_z85_decode_translation) try: return b85decode(s) except ValueError as e: raise ValueError(e.args[0].replace('base85', 'z85')) from None # Legacy interface. This code could be cleaned up since I don't believe # binascii has any line length limitations. It just doesn't seem worth it # though. The files should be opened in binary mode. MAXLINESIZE = 76 # Excluding the CRLF MAXBINSIZE = (MAXLINESIZE//4)*3 def encode(input, output): """Encode a file; input and output are binary files.""" while s := input.read(MAXBINSIZE): while len(s) < MAXBINSIZE and (ns := input.read(MAXBINSIZE-len(s))): s += ns line = binascii.b2a_base64(s) output.write(line) def decode(input, output): """Decode a file; input and output are binary files.""" while line := input.readline(): 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 decodebytes(s): """Decode a bytestring of base-64 data into a bytes object.""" _input_type_check(s) return binascii.a2b_base64(s) # Usable as a script... def main(): """Small main program""" import sys, getopt usage = f"""usage: {sys.argv[0]} [-h|-d|-e|-u] [file|-] -h: print this help message and exit -d, -u: decode -e: encode (default)""" try: opts, args = getopt.getopt(sys.argv[1:], 'hdeu') except getopt.error as msg: sys.stdout = sys.stderr print(msg) print(usage) 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 == '-h': print(usage); return if args and args[0] != '-': with open(args[0], 'rb') as f: func(f, sys.stdout.buffer) else: if sys.stdin.isatty(): # gh-138775: read terminal input data all at once to detect EOF import io data = sys.stdin.buffer.read() buffer = io.BytesIO(data) else: buffer = sys.stdin.buffer func(buffer, sys.stdout.buffer) if __name__ == '__main__': main()