| #! /usr/bin/env python3 |
| |
| """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 re |
| 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', |
| # 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. |
| """ |
| 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'+/')) |
| if validate and not re.fullmatch(b'[A-Za-z0-9+/]*={0,2}', s): |
| raise binascii.Error('Non-base64 digit found') |
| return binascii.a2b_base64(s) |
| |
| |
| 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): |
| global _b32tab2 |
| # 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') |
| 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): |
| global _b32rev |
| # 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') |
| # 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') |
| 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 re.search(b'[^0-9A-F]', s): |
| 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" Adobe encoding. |
| |
| wrapcol controls whether the output should have newline (b'\\n') characters |
| added to it. If this is non-zero, each output line will be at most this |
| many characters long. |
| |
| pad controls whether the input is padded to a multiple of 4 before |
| encoding. Note that the btoa implementation always pads. |
| |
| adobe controls whether the encoded byte sequence is framed with <~ and ~>, |
| which is used by the Adobe implementation. |
| """ |
| global _a85chars, _a85chars2 |
| # Delay the initialization of tables to not waste memory |
| # if the function is never called |
| if _a85chars 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" Adobe encoding. |
| |
| adobe controls whether the input sequence is in Adobe Ascii85 format (i.e. |
| is framed with <~ and ~>). |
| |
| 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. |
| |
| If pad is true, the input is padded with b'\\0' so its length is a multiple of |
| 4 bytes before encoding. |
| """ |
| global _b85chars, _b85chars2 |
| # Delay the initialization of tables to not waste memory |
| # if the function is never called |
| if _b85chars 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: |
| _b85dec = [None] * 256 |
| for i, c in enumerate(_b85alphabet): |
| _b85dec[c] = i |
| |
| 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 |
| |
| # 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 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 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 |
| 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() |