On Feb 11, 2008 4:11 PM, jam <[EMAIL PROTECTED]> wrote:
> The whole concept is an utter myth.
> I zip my data
> or bzip it
> or bzip2 it
> or steg it into a harmless picture
> or encrupt it
>
> As I said, an utter myth
Agreed :-)
[EMAIL PROTECTED]:~/code/cerulif$ cat cerulif.py
#!/usr/bin/env python
"""
Author: Kristian Erik Hermansen
CeRuLiF is a steganography tool useful for hiding messages in textual data
by exploiting the relationship of CR/LF character pairs.
"""
import sys, zlib
from optparse import OptionParser
parser = OptionParser('usage: %prog [options]', version='%prog 20070107')
parser.add_option('-i', '--input-file', action='store', type='string',
dest='ifile',
help='input file')
parser.add_option('-m', '--message-file', action='store', type='string',
dest='mfile',
help='message file containing secret')
parser.add_option('-o', '--output-file', action='store', type='string',
dest='ofile',
help='output file')
parser.add_option('-z', '--zip-message', action='store_true',
dest='zipit', default=False,
help='zlib the hidden message')
parser.add_option('-H', '--hide', action='store_true',
dest='hide', default=False,
help='embed a hidden message')
parser.add_option('-U', '--unhide', action='store_true',
dest='unhide', default=False,
help='unembed a hidden message')
parser.add_option('-p', '--parachute', action='store_false',
dest='parachute', default=True,
help='simple checks for non-cerulified input files')
# TODO: aes encryption support
(options, args) = parser.parse_args()
# required options, oxymoron
if options.ifile == None:
parser.error('You must specify an input file!')
# other bad things
if options.hide == True and options.unhide == True:
parser.error('You have to choose hide/unhide, but not both man!')
if options.hide == False and options.unhide == False:
parser.error('You have to choose whether to hide or unhide a message!')
if options.unhide == True and options.mfile == True:
parser.error('Dont specify a hidden input message when unhiding!')
# heh, yes we assume you only use reasonably sized files ;-P
fin = open(options.ifile)
bmes ='' # message buf
fout = '' # output handle
# configure output
if options.ofile == None:
fout = sys.stdout
else:
fout = open(options.ofile, 'w')
if options.hide == True:
# our secret message
if options.mfile == None:
# get from stdin until EOF
bmes = sys.stdin.read()
else:
# read from message file
bmes = open(options.mfile).read()
# compression support
if options.zipit == True:
bmes = zlib.compress(bmes)
# get CRLF/LFCR lines -- can't merely use readline() here dude
# ~spaghetti (+ dont want to hog mem with read())
def get_cerulif_chunk(f):
cr = lf = eof = 0
byte = ''
buf = ''
while cr == 0 or lf == 0:
byte = f.read(1)
if byte == '\n':
lf = 1
if f.read(1) != '\r':
f.seek(-1,1)
lf = 0
else:
cr = 1
if byte == '\r':
cr = 1
if f.read(1) != '\n':
f.seek(-1,1)
cr = 0
else:
lf = 1
if byte == '':
eof = 1
break
buf += byte
if eof != 1:
f.seek(-1,1)
buf += f.read(1)
return buf
# thx python-list
def bstr(n): # n in range 0-255
return ''.join([str(n >> x & 1) for x in (7,6,5,4,3,2,1,0)])
# take message chunk, embed bit, return string
def embed_bit_in_chunk(s, b):
t = s[0:-2]
if b == 1:
t += '\r'
t += '\n'
elif b == 0:
t += '\n'
t += '\r'
else:
print 'Bit should be 0 or 1!'
sys.exit(2)
return t
# take message chunk, unembed bit, return bit
def unembed_bit_from_chunk(s):
if s[-2] == '\r' and s[-1] == '\n':
return 1
elif s[-2] == '\n' and s[-1] == '\r':
return 0
else:
print 'We did not find a bit in this chunk!'
sys.exit(3)
if options.hide == True:
# magic goes here ... ohhh the hacks!
for c in bmes:
c_bstr = bstr(ord(c))
# iterate over the bits
for b in c_bstr:
chunk = get_cerulif_chunk(fin)
if chunk == '':
print '**********'
print 'We ran out of slack space necessary to steganize input!'
print '**********'
sys.exit(1)
else:
fout.write(embed_bit_in_chunk(chunk, int(b)))
# exhaust the remaining input file
while True:
chunk = get_cerulif_chunk(fin)
if chunk == '':
break
else:
fout.write(chunk)
if options.unhide == True:
while True:
chunk = get_cerulif_chunk(fin)
if chunk == '':
break
else:
bmes += str(unembed_bit_from_chunk(chunk))
# compression support
if options.zipit == True:
bmes = zlib.decompress(bmes)
if bmes[0:8] == '11111111':
if options.parachute == True:
print '**********'
print 'Looks like this file might not be CeRuLiFied!'
print '**********'
sys.exit(4)
else:
t = ''
for c in bmes:
t += c
if len(t) == 8 and t != '11111111':
fout.write(chr(int(t, 2)))
t = ''
--
Kristian Erik Hermansen
"Know something about everything and everything about something."
--
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