#! /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

import itertools

__all__ = [

# Legacy interface exports traditional RFC 1521 Base64 encodings

'encode', 'decode', 'encodebytes', 'decodebytes',

# Generalized interface for other encodings

'b64encode', 'b64decode', 'b32encode', 'b32decode',

'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 a byte string using Base64.

s is the byte string to encode. Optional altchars must 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.

The encoded byte string is returned.

"""

# Strip off the trailing newline

encoded = binascii.b2a_base64(s)[:-1]

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 a Base64 encoded byte string.

s is the byte string to decode. Optional altchars must be a

string of length 2 which specifies the alternative alphabet used

instead of the '+' and '/' characters.

The decoded string is returned. A binascii.Error is raised if s is

incorrectly padded.

If validate is False (the default), non-base64-alphabet characters are

discarded prior to the padding check. If validate is True,

non-base64-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.match(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 a byte string using the standard Base64 alphabet.

s is the byte string to encode. The encoded byte string is returned.

"""

return b64encode(s)

def standard_b64decode(s):

"""Decode a byte string encoded with the standard Base64 alphabet.

s is the byte string to decode. The decoded byte string is

returned. binascii.Error is raised if the input is incorrectly

padded or if there are non-alphabet characters present in the

input.

"""

return b64decode(s)

_urlsafe_encode_translation = bytes.maketrans(b'+/', b'-_')

_urlsafe_decode_translation = bytes.maketrans(b'-_', b'+/')

def urlsafe_b64encode(s):

"""Encode a byte string using a url-safe Base64 alphabet.

s is the byte string to encode. The encoded byte string is

returned. The alphabet uses '-' instead of '+' and '_' instead of

'/'.

"""

return b64encode(s).translate(_urlsafe_encode_translation)

def urlsafe_b64decode(s):

"""Decode a byte string encoded with the standard Base64 alphabet.

s is the byte string to decode. The decoded byte string is

returned. binascii.Error is raised if the input is incorrectly

padded or if there are non-alphabet characters present in the

input.

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

_b32alphabet = b'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567'

_b32tab = [bytes([i]) for i in _b32alphabet]

_b32tab2 = [a + b for a in _b32tab for b in _b32tab]

_b32rev = {v: k for k, v in enumerate(_b32alphabet)}

def b32encode(s):

"""Encode a byte string using Base32.

s is the byte string to encode. The encoded byte string is returned.

"""

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 + bytes(5 - leftover) # Don't use += !

encoded = bytearray()

from_bytes = int.from_bytes

b32tab2 = _b32tab2

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(s, casefold=False, map01=None):

"""Decode a Base32 encoded byte string.

s is the byte string to decode. Optional casefold is a flag

specifying whether a lowercase alphabet is acceptable as input.

For security purposes, the default is False.

RFC 3548 allows for optional mapping of the digit 0 (zero) to the

letter O (oh), and for optional mapping of the digit 1 (one) to

either the letter I (eye) or letter L (el). The optional argument

map01 when not None, specifies which letter the digit 1 should be

mapped to (when map01 is not None, the digit 0 is always mapped to

the letter O). For security purposes the default is None, so that

0 and 1 are not allowed in the input.

The decoded byte string is returned. binascii.Error is raised if

the input is incorrectly padded or if there are non-alphabet

characters present in the input.

"""

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

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 padchars:

acc <<= 5 * padchars

last = acc.to_bytes(5, 'big')

if padchars == 1:

decoded[-5:] = last[:-1]

elif padchars == 3:

decoded[-5:] = last[:-2]

elif padchars == 4:

decoded[-5:] = last[:-3]

elif padchars == 6:

decoded[-5:] = last[:-4]

else:

raise binascii.Error('Incorrect padding')

return bytes(decoded)

# RFC 3548, Base 16 Alphabet specifies uppercase, but hexlify() returns

# lowercase. The RFC also recommends against accepting input case

# insensitively.

def b16encode(s):

"""Encode a byte string using Base16.

s is the byte string to encode. The encoded byte string is returned.

"""

return binascii.hexlify(s).upper()

def b16decode(s, casefold=False):

"""Decode a Base16 encoded byte string.

s is the byte string to decode. Optional casefold is a flag

specifying whether a lowercase alphabet is acceptable as input.

For security purposes, the default is False.

The decoded byte string is returned. binascii.Error is raised if

s were incorrectly padded or if there are non-alphabet characters

present in the string.

"""

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

#

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)

a85chars2 = _a85chars2

a85chars = _a85chars

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)

_A85START = b"<~"

_A85END = b"~>"

_a85chars = [bytes([i]) for i in range(33, 118)]

_a85chars2 = [(a + b) for a in _a85chars for b in _a85chars]

def a85encode(b, *, foldspaces=False, wrapcol=0, pad=False, adobe=False):

"""Encode a byte string using Ascii85.

b is the byte string to encode. The encoded byte string is returned.

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 ('\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 string 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.

"""

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 an Ascii85 encoded byte string.

s is the byte string to decode.

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.

"""

b = _bytes_from_decode_data(b)

if adobe:

if not (b.startswith(_A85START) and b.endswith(_A85END)):

raise ValueError("Ascii85 encoded byte sequences must be bracketed "

"by {!r} and {!r}".format(_A85START, _A85END))

b = b[2:-2] # Strip off start/end markers

#

# 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

_b85chars = b"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ" \

b"abcdefghijklmnopqrstuvwxyz!#$%&()*+-;<=>?@^_`{|}~"

_b85chars = [bytes([i]) for i in _b85chars]

_b85chars2 = [(a + b) for a in _b85chars for b in _b85chars]

_b85dec = None

def b85encode(b, pad=False):

"""Encode an ASCII-encoded byte array in base85 format.

If pad is true, the input is padded with "\0" so its length is a multiple of

4 characters before encoding.

"""

return _85encode(b, _b85chars, _b85chars2, pad)

def b85decode(b):

"""Decode base85-encoded byte array"""

b = _bytes_from_decode_data(b)

global _b85dec

if _b85dec is None:

_b85dec = [None] * 256

for i, c in enumerate(_b85chars):

_b85dec[c[0]] = i

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 bytestring 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, use encodebytes()",

DeprecationWarning, 2)

return encodebytes(s)

def decodebytes(s):

"""Decode a bytestring of base-64 data into a bytestring."""

_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, 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()