symbian-qemu-0.9.1-12/python-win32-2.6.1/lib/base64.py
changeset 1 2fb8b9db1c86
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0:ffa851df0825 1:2fb8b9db1c86
       
     1 #! /usr/bin/env python
       
     2 
       
     3 """RFC 3548: Base16, Base32, Base64 Data Encodings"""
       
     4 
       
     5 # Modified 04-Oct-1995 by Jack Jansen to use binascii module
       
     6 # Modified 30-Dec-2003 by Barry Warsaw to add full RFC 3548 support
       
     7 
       
     8 import re
       
     9 import struct
       
    10 import binascii
       
    11 
       
    12 
       
    13 __all__ = [
       
    14     # Legacy interface exports traditional RFC 1521 Base64 encodings
       
    15     'encode', 'decode', 'encodestring', 'decodestring',
       
    16     # Generalized interface for other encodings
       
    17     'b64encode', 'b64decode', 'b32encode', 'b32decode',
       
    18     'b16encode', 'b16decode',
       
    19     # Standard Base64 encoding
       
    20     'standard_b64encode', 'standard_b64decode',
       
    21     # Some common Base64 alternatives.  As referenced by RFC 3458, see thread
       
    22     # starting at:
       
    23     #
       
    24     # http://zgp.org/pipermail/p2p-hackers/2001-September/000316.html
       
    25     'urlsafe_b64encode', 'urlsafe_b64decode',
       
    26     ]
       
    27 
       
    28 _translation = [chr(_x) for _x in range(256)]
       
    29 EMPTYSTRING = ''
       
    30 
       
    31 
       
    32 def _translate(s, altchars):
       
    33     translation = _translation[:]
       
    34     for k, v in altchars.items():
       
    35         translation[ord(k)] = v
       
    36     return s.translate(''.join(translation))
       
    37 
       
    38 
       
    39 
       
    40 # Base64 encoding/decoding uses binascii
       
    41 
       
    42 def b64encode(s, altchars=None):
       
    43     """Encode a string using Base64.
       
    44 
       
    45     s is the string to encode.  Optional altchars must be a string of at least
       
    46     length 2 (additional characters are ignored) which specifies an
       
    47     alternative alphabet for the '+' and '/' characters.  This allows an
       
    48     application to e.g. generate url or filesystem safe Base64 strings.
       
    49 
       
    50     The encoded string is returned.
       
    51     """
       
    52     # Strip off the trailing newline
       
    53     encoded = binascii.b2a_base64(s)[:-1]
       
    54     if altchars is not None:
       
    55         return _translate(encoded, {'+': altchars[0], '/': altchars[1]})
       
    56     return encoded
       
    57 
       
    58 
       
    59 def b64decode(s, altchars=None):
       
    60     """Decode a Base64 encoded string.
       
    61 
       
    62     s is the string to decode.  Optional altchars must be a string of at least
       
    63     length 2 (additional characters are ignored) which specifies the
       
    64     alternative alphabet used instead of the '+' and '/' characters.
       
    65 
       
    66     The decoded string is returned.  A TypeError is raised if s were
       
    67     incorrectly padded or if there are non-alphabet characters present in the
       
    68     string.
       
    69     """
       
    70     if altchars is not None:
       
    71         s = _translate(s, {altchars[0]: '+', altchars[1]: '/'})
       
    72     try:
       
    73         return binascii.a2b_base64(s)
       
    74     except binascii.Error, msg:
       
    75         # Transform this exception for consistency
       
    76         raise TypeError(msg)
       
    77 
       
    78 
       
    79 def standard_b64encode(s):
       
    80     """Encode a string using the standard Base64 alphabet.
       
    81 
       
    82     s is the string to encode.  The encoded string is returned.
       
    83     """
       
    84     return b64encode(s)
       
    85 
       
    86 def standard_b64decode(s):
       
    87     """Decode a string encoded with the standard Base64 alphabet.
       
    88 
       
    89     s is the string to decode.  The decoded string is returned.  A TypeError
       
    90     is raised if the string is incorrectly padded or if there are non-alphabet
       
    91     characters present in the string.
       
    92     """
       
    93     return b64decode(s)
       
    94 
       
    95 def urlsafe_b64encode(s):
       
    96     """Encode a string using a url-safe Base64 alphabet.
       
    97 
       
    98     s is the string to encode.  The encoded string is returned.  The alphabet
       
    99     uses '-' instead of '+' and '_' instead of '/'.
       
   100     """
       
   101     return b64encode(s, '-_')
       
   102 
       
   103 def urlsafe_b64decode(s):
       
   104     """Decode a string encoded with the standard Base64 alphabet.
       
   105 
       
   106     s is the string to decode.  The decoded string is returned.  A TypeError
       
   107     is raised if the string is incorrectly padded or if there are non-alphabet
       
   108     characters present in the string.
       
   109 
       
   110     The alphabet uses '-' instead of '+' and '_' instead of '/'.
       
   111     """
       
   112     return b64decode(s, '-_')
       
   113 
       
   114 
       
   115 
       
   116 # Base32 encoding/decoding must be done in Python
       
   117 _b32alphabet = {
       
   118     0: 'A',  9: 'J', 18: 'S', 27: '3',
       
   119     1: 'B', 10: 'K', 19: 'T', 28: '4',
       
   120     2: 'C', 11: 'L', 20: 'U', 29: '5',
       
   121     3: 'D', 12: 'M', 21: 'V', 30: '6',
       
   122     4: 'E', 13: 'N', 22: 'W', 31: '7',
       
   123     5: 'F', 14: 'O', 23: 'X',
       
   124     6: 'G', 15: 'P', 24: 'Y',
       
   125     7: 'H', 16: 'Q', 25: 'Z',
       
   126     8: 'I', 17: 'R', 26: '2',
       
   127     }
       
   128 
       
   129 _b32tab = _b32alphabet.items()
       
   130 _b32tab.sort()
       
   131 _b32tab = [v for k, v in _b32tab]
       
   132 _b32rev = dict([(v, long(k)) for k, v in _b32alphabet.items()])
       
   133 
       
   134 
       
   135 def b32encode(s):
       
   136     """Encode a string using Base32.
       
   137 
       
   138     s is the string to encode.  The encoded string is returned.
       
   139     """
       
   140     parts = []
       
   141     quanta, leftover = divmod(len(s), 5)
       
   142     # Pad the last quantum with zero bits if necessary
       
   143     if leftover:
       
   144         s += ('\0' * (5 - leftover))
       
   145         quanta += 1
       
   146     for i in range(quanta):
       
   147         # c1 and c2 are 16 bits wide, c3 is 8 bits wide.  The intent of this
       
   148         # code is to process the 40 bits in units of 5 bits.  So we take the 1
       
   149         # leftover bit of c1 and tack it onto c2.  Then we take the 2 leftover
       
   150         # bits of c2 and tack them onto c3.  The shifts and masks are intended
       
   151         # to give us values of exactly 5 bits in width.
       
   152         c1, c2, c3 = struct.unpack('!HHB', s[i*5:(i+1)*5])
       
   153         c2 += (c1 & 1) << 16 # 17 bits wide
       
   154         c3 += (c2 & 3) << 8  # 10 bits wide
       
   155         parts.extend([_b32tab[c1 >> 11],         # bits 1 - 5
       
   156                       _b32tab[(c1 >> 6) & 0x1f], # bits 6 - 10
       
   157                       _b32tab[(c1 >> 1) & 0x1f], # bits 11 - 15
       
   158                       _b32tab[c2 >> 12],         # bits 16 - 20 (1 - 5)
       
   159                       _b32tab[(c2 >> 7) & 0x1f], # bits 21 - 25 (6 - 10)
       
   160                       _b32tab[(c2 >> 2) & 0x1f], # bits 26 - 30 (11 - 15)
       
   161                       _b32tab[c3 >> 5],          # bits 31 - 35 (1 - 5)
       
   162                       _b32tab[c3 & 0x1f],        # bits 36 - 40 (1 - 5)
       
   163                       ])
       
   164     encoded = EMPTYSTRING.join(parts)
       
   165     # Adjust for any leftover partial quanta
       
   166     if leftover == 1:
       
   167         return encoded[:-6] + '======'
       
   168     elif leftover == 2:
       
   169         return encoded[:-4] + '===='
       
   170     elif leftover == 3:
       
   171         return encoded[:-3] + '==='
       
   172     elif leftover == 4:
       
   173         return encoded[:-1] + '='
       
   174     return encoded
       
   175 
       
   176 
       
   177 def b32decode(s, casefold=False, map01=None):
       
   178     """Decode a Base32 encoded string.
       
   179 
       
   180     s is the string to decode.  Optional casefold is a flag specifying whether
       
   181     a lowercase alphabet is acceptable as input.  For security purposes, the
       
   182     default is False.
       
   183 
       
   184     RFC 3548 allows for optional mapping of the digit 0 (zero) to the letter O
       
   185     (oh), and for optional mapping of the digit 1 (one) to either the letter I
       
   186     (eye) or letter L (el).  The optional argument map01 when not None,
       
   187     specifies which letter the digit 1 should be mapped to (when map01 is not
       
   188     None, the digit 0 is always mapped to the letter O).  For security
       
   189     purposes the default is None, so that 0 and 1 are not allowed in the
       
   190     input.
       
   191 
       
   192     The decoded string is returned.  A TypeError is raised if s were
       
   193     incorrectly padded or if there are non-alphabet characters present in the
       
   194     string.
       
   195     """
       
   196     quanta, leftover = divmod(len(s), 8)
       
   197     if leftover:
       
   198         raise TypeError('Incorrect padding')
       
   199     # Handle section 2.4 zero and one mapping.  The flag map01 will be either
       
   200     # False, or the character to map the digit 1 (one) to.  It should be
       
   201     # either L (el) or I (eye).
       
   202     if map01:
       
   203         s = _translate(s, {'0': 'O', '1': map01})
       
   204     if casefold:
       
   205         s = s.upper()
       
   206     # Strip off pad characters from the right.  We need to count the pad
       
   207     # characters because this will tell us how many null bytes to remove from
       
   208     # the end of the decoded string.
       
   209     padchars = 0
       
   210     mo = re.search('(?P<pad>[=]*)$', s)
       
   211     if mo:
       
   212         padchars = len(mo.group('pad'))
       
   213         if padchars > 0:
       
   214             s = s[:-padchars]
       
   215     # Now decode the full quanta
       
   216     parts = []
       
   217     acc = 0
       
   218     shift = 35
       
   219     for c in s:
       
   220         val = _b32rev.get(c)
       
   221         if val is None:
       
   222             raise TypeError('Non-base32 digit found')
       
   223         acc += _b32rev[c] << shift
       
   224         shift -= 5
       
   225         if shift < 0:
       
   226             parts.append(binascii.unhexlify('%010x' % acc))
       
   227             acc = 0
       
   228             shift = 35
       
   229     # Process the last, partial quanta
       
   230     last = binascii.unhexlify('%010x' % acc)
       
   231     if padchars == 0:
       
   232         last = ''                       # No characters
       
   233     elif padchars == 1:
       
   234         last = last[:-1]
       
   235     elif padchars == 3:
       
   236         last = last[:-2]
       
   237     elif padchars == 4:
       
   238         last = last[:-3]
       
   239     elif padchars == 6:
       
   240         last = last[:-4]
       
   241     else:
       
   242         raise TypeError('Incorrect padding')
       
   243     parts.append(last)
       
   244     return EMPTYSTRING.join(parts)
       
   245 
       
   246 
       
   247 
       
   248 # RFC 3548, Base 16 Alphabet specifies uppercase, but hexlify() returns
       
   249 # lowercase.  The RFC also recommends against accepting input case
       
   250 # insensitively.
       
   251 def b16encode(s):
       
   252     """Encode a string using Base16.
       
   253 
       
   254     s is the string to encode.  The encoded string is returned.
       
   255     """
       
   256     return binascii.hexlify(s).upper()
       
   257 
       
   258 
       
   259 def b16decode(s, casefold=False):
       
   260     """Decode a Base16 encoded string.
       
   261 
       
   262     s is the string to decode.  Optional casefold is a flag specifying whether
       
   263     a lowercase alphabet is acceptable as input.  For security purposes, the
       
   264     default is False.
       
   265 
       
   266     The decoded string is returned.  A TypeError is raised if s were
       
   267     incorrectly padded or if there are non-alphabet characters present in the
       
   268     string.
       
   269     """
       
   270     if casefold:
       
   271         s = s.upper()
       
   272     if re.search('[^0-9A-F]', s):
       
   273         raise TypeError('Non-base16 digit found')
       
   274     return binascii.unhexlify(s)
       
   275 
       
   276 
       
   277 
       
   278 # Legacy interface.  This code could be cleaned up since I don't believe
       
   279 # binascii has any line length limitations.  It just doesn't seem worth it
       
   280 # though.
       
   281 
       
   282 MAXLINESIZE = 76 # Excluding the CRLF
       
   283 MAXBINSIZE = (MAXLINESIZE//4)*3
       
   284 
       
   285 def encode(input, output):
       
   286     """Encode a file."""
       
   287     while True:
       
   288         s = input.read(MAXBINSIZE)
       
   289         if not s:
       
   290             break
       
   291         while len(s) < MAXBINSIZE:
       
   292             ns = input.read(MAXBINSIZE-len(s))
       
   293             if not ns:
       
   294                 break
       
   295             s += ns
       
   296         line = binascii.b2a_base64(s)
       
   297         output.write(line)
       
   298 
       
   299 
       
   300 def decode(input, output):
       
   301     """Decode a file."""
       
   302     while True:
       
   303         line = input.readline()
       
   304         if not line:
       
   305             break
       
   306         s = binascii.a2b_base64(line)
       
   307         output.write(s)
       
   308 
       
   309 
       
   310 def encodestring(s):
       
   311     """Encode a string into multiple lines of base-64 data."""
       
   312     pieces = []
       
   313     for i in range(0, len(s), MAXBINSIZE):
       
   314         chunk = s[i : i + MAXBINSIZE]
       
   315         pieces.append(binascii.b2a_base64(chunk))
       
   316     return "".join(pieces)
       
   317 
       
   318 
       
   319 def decodestring(s):
       
   320     """Decode a string."""
       
   321     return binascii.a2b_base64(s)
       
   322 
       
   323 
       
   324 
       
   325 # Useable as a script...
       
   326 def test():
       
   327     """Small test program"""
       
   328     import sys, getopt
       
   329     try:
       
   330         opts, args = getopt.getopt(sys.argv[1:], 'deut')
       
   331     except getopt.error, msg:
       
   332         sys.stdout = sys.stderr
       
   333         print msg
       
   334         print """usage: %s [-d|-e|-u|-t] [file|-]
       
   335         -d, -u: decode
       
   336         -e: encode (default)
       
   337         -t: encode and decode string 'Aladdin:open sesame'"""%sys.argv[0]
       
   338         sys.exit(2)
       
   339     func = encode
       
   340     for o, a in opts:
       
   341         if o == '-e': func = encode
       
   342         if o == '-d': func = decode
       
   343         if o == '-u': func = decode
       
   344         if o == '-t': test1(); return
       
   345     if args and args[0] != '-':
       
   346         func(open(args[0], 'rb'), sys.stdout)
       
   347     else:
       
   348         func(sys.stdin, sys.stdout)
       
   349 
       
   350 
       
   351 def test1():
       
   352     s0 = "Aladdin:open sesame"
       
   353     s1 = encodestring(s0)
       
   354     s2 = decodestring(s1)
       
   355     print s0, repr(s1), s2
       
   356 
       
   357 
       
   358 if __name__ == '__main__':
       
   359     test()