gpgparticipants/gpgparticipants-prefill

   1 #!/usr/bin/env python2
   2 """Fill in the first digits of the hash in a form created by gpgparticipants."""
   3
   4 __version__ = "1.0"
   5
   6 __author__ = "Stefan Huber"
   7 __email__ = "shuber@sthu.org"
   8 __copyright__ = "Copyright 2013, Stefan Huber"
   9
  10 __license__ = "MIT"
  11
  12 # Permission is hereby granted, free of charge, to any person
  13 # obtaining a copy of this software and associated documentation
  14 # files (the "Software"), to deal in the Software without
  15 # restriction, including without limitation the rights to use,
  16 # copy, modify, merge, publish, distribute, sublicense, and/or sell
  17 # copies of the Software, and to permit persons to whom the
  18 # Software is furnished to do so, subject to the following
  19 # conditions:
  20 #
  21 # The above copyright notice and this permission notice shall be
  22 # included in all copies or substantial portions of the Software.
  23 #
  24 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  25 # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  26 # OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  27 # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  28 # HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  29 # WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  30 # FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  31 # OTHER DEALINGS IN THE SOFTWARE.
  32
  33
  34 import sys
  35 import hashlib
  36 import getopt
  37
  38
  39 def insertspaces(s):
  40     """Inserts a space after every 4-th character, and three spaces after every
  41     8-th character of string s."""
  42
  43     def inpacks(s, n):
  44         while len(s) > 0:
  45             yield s[0:n]
  46             s = s[n:]
  47
  48     out = "   ".join([ " ".join(inpacks(octp, 4)) for octp in inpacks(s, 8)])
  49     return out
  50
  51
  52 def range_hex(length):
  53     """Give all hex-strings from 00...0 until ff...f of given length."""
  54
  55     if length == 0:
  56         yield ""
  57
  58     elif length == 1:
  59         for c in "0123456789abcdef":
  60             yield c
  61     elif length > 1:
  62         for prefix in range_hex(length-1):
  63             for postfix in range_hex(1):
  64                 yield prefix + postfix
  65
  66
  67 def usage():
  68     """Print --help text"""
  69
  70     print("""Usage:
  71   {0} <emptylist> <filledlist>
  72   {0} --help
  73   {0} -h
  74
  75 Takes a file produced by gpgparticipants as <emptylist> and trys to fill in
  76 some digits into the SHA256 field such that the resulting list actually has
  77 a SHA256 checksum that starts with those digits. Whenever a match is found a
  78 file with the digits filled in is written to `<filledlist>.DIGITS`.
  79
  80 OPTIONS:
  81
  82   --fastforward        If a match is found of given length and --fastforward
  83                        is given then the program immediately jumps to the next
  84                        length.
  85   --min-length NUM     Start search with given length
  86
  87 """.format(sys.argv[0]))
  88
  89
  90 if __name__ == "__main__":
  91
  92     fastforward = False
  93     minlength = 1
  94
  95     optlist, args = getopt.getopt(sys.argv[1:], 'h', ['fastforward', 'min-length='])
  96     for o, a in optlist:
  97
  98         if o in ("-h", "--help"):
  99             usage()
 100             exit(0)
 101
 102         if o in ("--fastforward"):
 103             fastforward = True
 104
 105         if o in ("--min-length"):
 106             minlength = int(a)
 107
 108     if len(args) < 2:
 109         print >>sys.stderr, "You need to give two filenames."""
 110         exit(1)
 111
 112     emptyfile = open(args[0]).read()
 113
 114     idx = emptyfile.find("SHA256 Checksum:")
 115     idx = emptyfile.find("_", idx)
 116
 117     for l in range(minlength, 32):
 118         print "Looking at length", l
 119
 120         for h in range_hex(l):
 121
 122             H = insertspaces(h.upper())
 123             filledfile = emptyfile[:idx] + H + emptyfile[idx+len(H):]
 124             actual = hashlib.sha256(filledfile).hexdigest()
 125
 126             if actual[:len(h)] == h:
 127                 print "Found: ", H
 128                 open(args[1] + "." + h, "w").write(filledfile)
 129
 130                 if fastforward:
 131                     break