360 lines
11 KiB
Python
Executable file
360 lines
11 KiB
Python
Executable file
#! /usr/bin/env python
|
||
|
||
"""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
|
||
|
||
import re
|
||
import struct
|
||
import binascii
|
||
|
||
|
||
__all__ = [
|
||
# Legacy interface exports traditional RFC 1521 Base64 encodings
|
||
'encode', 'decode', 'encodestring', 'decodestring',
|
||
# 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',
|
||
]
|
||
|
||
_translation = [chr(_x) for _x in range(256)]
|
||
EMPTYSTRING = ''
|
||
|
||
|
||
def _translate(s, altchars):
|
||
translation = _translation[:]
|
||
for k, v in altchars.items():
|
||
translation[ord(k)] = v
|
||
return s.translate(''.join(translation))
|
||
|
||
|
||
|
||
# Base64 encoding/decoding uses binascii
|
||
|
||
def b64encode(s, altchars=None):
|
||
"""Encode a string using Base64.
|
||
|
||
s is the string to encode. Optional altchars must be a string of at least
|
||
length 2 (additional characters are ignored) 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 string is returned.
|
||
"""
|
||
# Strip off the trailing newline
|
||
encoded = binascii.b2a_base64(s)[:-1]
|
||
if altchars is not None:
|
||
return _translate(encoded, {'+': altchars[0], '/': altchars[1]})
|
||
return encoded
|
||
|
||
|
||
def b64decode(s, altchars=None):
|
||
"""Decode a Base64 encoded string.
|
||
|
||
s is the string to decode. Optional altchars must be a string of at least
|
||
length 2 (additional characters are ignored) which specifies the
|
||
alternative alphabet used instead of the '+' and '/' characters.
|
||
|
||
The decoded string is returned. A TypeError is raised if s were
|
||
incorrectly padded or if there are non-alphabet characters present in the
|
||
string.
|
||
"""
|
||
if altchars is not None:
|
||
s = _translate(s, {altchars[0]: '+', altchars[1]: '/'})
|
||
try:
|
||
return binascii.a2b_base64(s)
|
||
except binascii.Error, msg:
|
||
# Transform this exception for consistency
|
||
raise TypeError(msg)
|
||
|
||
|
||
def standard_b64encode(s):
|
||
"""Encode a string using the standard Base64 alphabet.
|
||
|
||
s is the string to encode. The encoded string is returned.
|
||
"""
|
||
return b64encode(s)
|
||
|
||
def standard_b64decode(s):
|
||
"""Decode a string encoded with the standard Base64 alphabet.
|
||
|
||
s is the string to decode. The decoded string is returned. A TypeError
|
||
is raised if the string is incorrectly padded or if there are non-alphabet
|
||
characters present in the string.
|
||
"""
|
||
return b64decode(s)
|
||
|
||
def urlsafe_b64encode(s):
|
||
"""Encode a string using a url-safe Base64 alphabet.
|
||
|
||
s is the string to encode. The encoded string is returned. The alphabet
|
||
uses '-' instead of '+' and '_' instead of '/'.
|
||
"""
|
||
return b64encode(s, '-_')
|
||
|
||
def urlsafe_b64decode(s):
|
||
"""Decode a string encoded with the standard Base64 alphabet.
|
||
|
||
s is the string to decode. The decoded string is returned. A TypeError
|
||
is raised if the string is incorrectly padded or if there are non-alphabet
|
||
characters present in the string.
|
||
|
||
The alphabet uses '-' instead of '+' and '_' instead of '/'.
|
||
"""
|
||
return b64decode(s, '-_')
|
||
|
||
|
||
|
||
# Base32 encoding/decoding must be done in Python
|
||
_b32alphabet = {
|
||
0: 'A', 9: 'J', 18: 'S', 27: '3',
|
||
1: 'B', 10: 'K', 19: 'T', 28: '4',
|
||
2: 'C', 11: 'L', 20: 'U', 29: '5',
|
||
3: 'D', 12: 'M', 21: 'V', 30: '6',
|
||
4: 'E', 13: 'N', 22: 'W', 31: '7',
|
||
5: 'F', 14: 'O', 23: 'X',
|
||
6: 'G', 15: 'P', 24: 'Y',
|
||
7: 'H', 16: 'Q', 25: 'Z',
|
||
8: 'I', 17: 'R', 26: '2',
|
||
}
|
||
|
||
_b32tab = _b32alphabet.items()
|
||
_b32tab.sort()
|
||
_b32tab = [v for k, v in _b32tab]
|
||
_b32rev = dict([(v, long(k)) for k, v in _b32alphabet.items()])
|
||
|
||
|
||
def b32encode(s):
|
||
"""Encode a string using Base32.
|
||
|
||
s is the string to encode. The encoded string is returned.
|
||
"""
|
||
parts = []
|
||
quanta, leftover = divmod(len(s), 5)
|
||
# Pad the last quantum with zero bits if necessary
|
||
if leftover:
|
||
s += ('\0' * (5 - leftover))
|
||
quanta += 1
|
||
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
|
||
parts.extend([_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)
|
||
])
|
||
encoded = EMPTYSTRING.join(parts)
|
||
# Adjust for any leftover partial quanta
|
||
if leftover == 1:
|
||
return encoded[:-6] + '======'
|
||
elif leftover == 2:
|
||
return encoded[:-4] + '===='
|
||
elif leftover == 3:
|
||
return encoded[:-3] + '==='
|
||
elif leftover == 4:
|
||
return encoded[:-1] + '='
|
||
return encoded
|
||
|
||
|
||
def b32decode(s, casefold=False, map01=None):
|
||
"""Decode a Base32 encoded string.
|
||
|
||
s is the 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 string is returned. A TypeError is raised if s were
|
||
incorrectly padded or if there are non-alphabet characters present in the
|
||
string.
|
||
"""
|
||
quanta, leftover = divmod(len(s), 8)
|
||
if leftover:
|
||
raise TypeError('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:
|
||
s = _translate(s, {'0': 'O', '1': 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('(?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('%010x' % acc))
|
||
acc = 0
|
||
shift = 35
|
||
# Process the last, partial quanta
|
||
last = binascii.unhexlify('%010x' % acc)
|
||
if padchars == 0:
|
||
last = '' # 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 TypeError('Incorrect padding')
|
||
parts.append(last)
|
||
return EMPTYSTRING.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 string using Base16.
|
||
|
||
s is the string to encode. The encoded string is returned.
|
||
"""
|
||
return binascii.hexlify(s).upper()
|
||
|
||
|
||
def b16decode(s, casefold=False):
|
||
"""Decode a Base16 encoded string.
|
||
|
||
s is the 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 string is returned. A TypeError is raised if s were
|
||
incorrectly padded or if there are non-alphabet characters present in the
|
||
string.
|
||
"""
|
||
if casefold:
|
||
s = s.upper()
|
||
if re.search('[^0-9A-F]', s):
|
||
raise TypeError('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.
|
||
|
||
MAXLINESIZE = 76 # Excluding the CRLF
|
||
MAXBINSIZE = (MAXLINESIZE//4)*3
|
||
|
||
def encode(input, output):
|
||
"""Encode a file."""
|
||
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."""
|
||
while True:
|
||
line = input.readline()
|
||
if not line:
|
||
break
|
||
s = binascii.a2b_base64(line)
|
||
output.write(s)
|
||
|
||
|
||
def encodestring(s):
|
||
"""Encode a string into multiple lines of base-64 data."""
|
||
pieces = []
|
||
for i in range(0, len(s), MAXBINSIZE):
|
||
chunk = s[i : i + MAXBINSIZE]
|
||
pieces.append(binascii.b2a_base64(chunk))
|
||
return "".join(pieces)
|
||
|
||
|
||
def decodestring(s):
|
||
"""Decode a string."""
|
||
return binascii.a2b_base64(s)
|
||
|
||
|
||
|
||
# Useable as a script...
|
||
def test():
|
||
"""Small test program"""
|
||
import sys, getopt
|
||
try:
|
||
opts, args = getopt.getopt(sys.argv[1:], 'deut')
|
||
except getopt.error, 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': test1(); return
|
||
if args and args[0] != '-':
|
||
with open(args[0], 'rb') as f:
|
||
func(f, sys.stdout)
|
||
else:
|
||
func(sys.stdin, sys.stdout)
|
||
|
||
|
||
def test1():
|
||
s0 = "Aladdin:open sesame"
|
||
s1 = encodestring(s0)
|
||
s2 = decodestring(s1)
|
||
print s0, repr(s1), s2
|
||
|
||
|
||
if __name__ == '__main__':
|
||
test()
|