[Python-checkins] python/dist/src/Lib base64.py,1.13,1.14
bwarsaw at users.sourceforge.net
bwarsaw at users.sourceforge.net
Sat Jan 3 20:12:28 EST 2004
Update of /cvsroot/python/python/dist/src/Lib
In directory sc8-pr-cvs1:/tmp/cvs-serv25840/Lib
Modified Files:
base64.py
Log Message:
Added more complete RFC 3548 support for Base64, Base32, and Base16
encoding and decoding, including optional case folding and optional
alternative alphabets.
Index: base64.py
===================================================================
RCS file: /cvsroot/python/python/dist/src/Lib/base64.py,v
retrieving revision 1.13
retrieving revision 1.14
diff -C2 -d -r1.13 -r1.14
*** base64.py 4 Sep 2001 19:14:13 -0000 1.13
--- base64.py 4 Jan 2004 01:12:26 -0000 1.14
***************
*** 1,11 ****
#! /usr/bin/env python
! """Conversions to/from base64 transport encoding as per RFC-1521."""
! # Modified 04-Oct-95 by Jack to use binascii module
import binascii
! __all__ = ["encode","decode","encodestring","decodestring"]
MAXLINESIZE = 76 # Excluding the CRLF
--- 1,279 ----
#! /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
! 'freenet_b64encode', 'freenet_b64decode',
! '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 = [v for v in _b32alphabet.values()]
! _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(hex(acc)[2:-1]))
! acc = 0
! shift = 35
! # Process the last, partial quanta
! last = binascii.unhexlify(hex(acc)[2:-1])
! if padchars == 1:
! last = last[:-1]
! elif padchars == 3:
! last = last[:-2]
! elif padchars == 4:
! last = last[:-3]
! elif padchars == 6:
! last = last[:-4]
! elif padchars <> 0:
! 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
***************
*** 14,35 ****
def encode(input, output):
"""Encode a file."""
! while 1:
s = input.read(MAXBINSIZE)
! if not s: break
while len(s) < MAXBINSIZE:
ns = input.read(MAXBINSIZE-len(s))
! if not ns: break
! s = s + ns
line = binascii.b2a_base64(s)
output.write(line)
def decode(input, output):
"""Decode a file."""
! while 1:
line = input.readline()
! if not line: break
s = binascii.a2b_base64(line)
output.write(s)
def encodestring(s):
"""Encode a string."""
--- 282,308 ----
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."""
***************
*** 40,47 ****
--- 313,324 ----
return "".join(pieces)
+
def decodestring(s):
"""Decode a string."""
return binascii.a2b_base64(s)
+
+
+ # Useable as a script...
def test():
"""Small test program"""
***************
*** 68,71 ****
--- 345,349 ----
func(sys.stdin, sys.stdout)
+
def test1():
s0 = "Aladdin:open sesame"
***************
*** 73,76 ****
--- 351,355 ----
s2 = decodestring(s1)
print s0, `s1`, s2
+
if __name__ == '__main__':
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