411 lines
14 KiB
Python
411 lines
14 KiB
Python
#! /usr/bin/env python3
|
|
|
|
"""RFC 3548: Base16, Base32, Base64 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 1521 Base64 encodings
|
|
'encode', 'decode', 'encodebytes', 'decodebytes',
|
|
# Generalized interface for other encodings
|
|
'b64encode', 'b64decode', 'b32encode', 'b32decode',
|
|
'b16encode', 'b16decode',
|
|
# 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')
|
|
elif isinstance(s, bytes_types):
|
|
return s
|
|
else:
|
|
raise TypeError("argument should be bytes or ASCII string, not %s" % s.__class__.__name__)
|
|
|
|
|
|
|
|
# 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.
|
|
"""
|
|
if not isinstance(s, bytes_types):
|
|
raise TypeError("expected bytes, not %s" % s.__class__.__name__)
|
|
# Strip off the trailing newline
|
|
encoded = binascii.b2a_base64(s)[:-1]
|
|
if altchars is not None:
|
|
if not isinstance(altchars, bytes_types):
|
|
raise TypeError("expected bytes, not %s"
|
|
% altchars.__class__.__name__)
|
|
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 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 = {
|
|
0: b'A', 9: b'J', 18: b'S', 27: b'3',
|
|
1: b'B', 10: b'K', 19: b'T', 28: b'4',
|
|
2: b'C', 11: b'L', 20: b'U', 29: b'5',
|
|
3: b'D', 12: b'M', 21: b'V', 30: b'6',
|
|
4: b'E', 13: b'N', 22: b'W', 31: b'7',
|
|
5: b'F', 14: b'O', 23: b'X',
|
|
6: b'G', 15: b'P', 24: b'Y',
|
|
7: b'H', 16: b'Q', 25: b'Z',
|
|
8: b'I', 17: b'R', 26: b'2',
|
|
}
|
|
|
|
_b32tab = [v[0] for k, v in sorted(_b32alphabet.items())]
|
|
_b32rev = dict([(v[0], k) for k, v in _b32alphabet.items()])
|
|
|
|
|
|
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):
|
|
raise TypeError("expected bytes, not %s" % s.__class__.__name__)
|
|
quanta, leftover = divmod(len(s), 5)
|
|
# Pad the last quantum with zero bits if necessary
|
|
if leftover:
|
|
s = s + bytes(5 - leftover) # Don't use += !
|
|
quanta += 1
|
|
encoded = bytes()
|
|
for i in range(quanta):
|
|
# c1 and c2 are 16 bits wide, c3 is 8 bits wide. The intent of this
|
|
# code is to process the 40 bits in units of 5 bits. So we take the 1
|
|
# leftover bit of c1 and tack it onto c2. Then we take the 2 leftover
|
|
# bits of c2 and tack them onto c3. The shifts and masks are intended
|
|
# to give us values of exactly 5 bits in width.
|
|
c1, c2, c3 = struct.unpack('!HHB', s[i*5:(i+1)*5])
|
|
c2 += (c1 & 1) << 16 # 17 bits wide
|
|
c3 += (c2 & 3) << 8 # 10 bits wide
|
|
encoded += bytes([_b32tab[c1 >> 11], # bits 1 - 5
|
|
_b32tab[(c1 >> 6) & 0x1f], # bits 6 - 10
|
|
_b32tab[(c1 >> 1) & 0x1f], # bits 11 - 15
|
|
_b32tab[c2 >> 12], # bits 16 - 20 (1 - 5)
|
|
_b32tab[(c2 >> 7) & 0x1f], # bits 21 - 25 (6 - 10)
|
|
_b32tab[(c2 >> 2) & 0x1f], # bits 26 - 30 (11 - 15)
|
|
_b32tab[c3 >> 5], # bits 31 - 35 (1 - 5)
|
|
_b32tab[c3 & 0x1f], # bits 36 - 40 (1 - 5)
|
|
])
|
|
# Adjust for any leftover partial quanta
|
|
if leftover == 1:
|
|
return encoded[:-6] + b'======'
|
|
elif leftover == 2:
|
|
return encoded[:-4] + b'===='
|
|
elif leftover == 3:
|
|
return encoded[:-3] + b'==='
|
|
elif leftover == 4:
|
|
return encoded[:-1] + b'='
|
|
return 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)
|
|
quanta, leftover = divmod(len(s), 8)
|
|
if leftover:
|
|
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.
|
|
padchars = 0
|
|
mo = re.search(b'(?P<pad>[=]*)$', s)
|
|
if mo:
|
|
padchars = len(mo.group('pad'))
|
|
if padchars > 0:
|
|
s = s[:-padchars]
|
|
# Now decode the full quanta
|
|
parts = []
|
|
acc = 0
|
|
shift = 35
|
|
for c in s:
|
|
val = _b32rev.get(c)
|
|
if val is None:
|
|
raise TypeError('Non-base32 digit found')
|
|
acc += _b32rev[c] << shift
|
|
shift -= 5
|
|
if shift < 0:
|
|
parts.append(binascii.unhexlify(bytes('%010x' % acc, "ascii")))
|
|
acc = 0
|
|
shift = 35
|
|
# Process the last, partial quanta
|
|
last = binascii.unhexlify(bytes('%010x' % acc, "ascii"))
|
|
if padchars == 0:
|
|
last = b'' # No characters
|
|
elif padchars == 1:
|
|
last = last[:-1]
|
|
elif padchars == 3:
|
|
last = last[:-2]
|
|
elif padchars == 4:
|
|
last = last[:-3]
|
|
elif padchars == 6:
|
|
last = last[:-4]
|
|
else:
|
|
raise binascii.Error('Incorrect padding')
|
|
parts.append(last)
|
|
return b''.join(parts)
|
|
|
|
|
|
|
|
# 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.
|
|
"""
|
|
if not isinstance(s, bytes_types):
|
|
raise TypeError("expected bytes, not %s" % s.__class__.__name__)
|
|
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)
|
|
|
|
|
|
|
|
# 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 encodebytes(s):
|
|
"""Encode a bytestring into a bytestring containing multiple lines
|
|
of base-64 data."""
|
|
if not isinstance(s, bytes_types):
|
|
raise TypeError("expected bytes, not %s" % s.__class__.__name__)
|
|
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."""
|
|
if not isinstance(s, bytes_types):
|
|
raise TypeError("expected bytes, not %s" % s.__class__.__name__)
|
|
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()
|