#!/usr/bin/env python
'''zcrypt - File encryption compression / decryption decompression

SYNOPSIS
    zcrypt [-d] key [source [dest]]

DESCRIPTION
    key is the encryption key which is used for encryption and corresponding
    decryption.

    source and dest are source and destination file names. If source is - then
    stdin is used, if dest is - the stdout is used. If dest is omitted then
    stdout is used. If both source and dest are omitted the stdin and stdout
    are used.

OPTIONS
    --help
        Print this documentation.

    -d
        Decrypt the source.
    
AUTHOR
    Written by Stuart Rackham, <srackham@methods.co.nz>

COPYING
    Copyright (C) 2000 Stuart Rackham. Free use of this software is granted
    under the terms of the GNU General Public License (GPL).
'''

import sys, os, zlib, rotor

'''Version History:
1.0     20 July 2000    Initial release.
1.0.1   22 July 2000    Added --help option.
'''
VERSION = "1.0.1"
BLK_SIZE = 8*1024

def zcrypt(key, src, dst):
    '''Compress and encrypt src file object to dst file object.
    key is the encryption key string.'''
    r = rotor.newrotor(key)
    z = zlib.compressobj()
    while 1:
        # Compress then encrypt else the randomising effect of encryption will
        # result in poor compression ratios.
        s = src.read(BLK_SIZE)
        if not s: break
        s = z.compress(s)
        dst.write(r.encryptmore(s))
    dst.write(r.encryptmore(z.flush()))

def zdecrypt(key, src, dst):
    '''Decrypt and decompress src file object to dst file object.
    key is the encryption key string.'''
    r = rotor.newrotor(key)
    z = zlib.decompressobj()
    while 1:
        s = src.read(BLK_SIZE)
        if not s: break
        s = r.decryptmore(s)
        dst.write(z.decompress(s))
    dst.write(z.flush())

def usage():
    cmd = os.path.basename(sys.argv[0])
    sys.stderr.write("Usage: %s [-d] [--help] key [srcfile [dstfile]]\n" % cmd)

def main():
    # Process command line options.
    import getopt
    opts,args = getopt.getopt(sys.argv[1:],"d",["help"])
    decrypt = 0
    for o,v in opts:
        if o == '--help':
            print __doc__
            sys.exit(0)
        if o == '-d':
            decrypt = 1
    if len(args) < 1 or len(args) > 3:
        usage()
        sys.exit(1)
    if len(args) == 1 or args[1] == '-':
        src = sys.stdin
    else:
        src = open(args[1],"rb")
    if len(args) == 2 or args[2] == '-':
        dst = sys.stdout
    else:
        dst = open(args[2],"wb+")
    if decrypt:
        zdecrypt(args[0], src, dst)
    else:
        zcrypt(args[0], src, dst)
    src.close()
    dst.close()

if __name__ == "__main__":
    try:
        main()
    except (KeyboardInterrupt, SystemExit):
        pass
    except:
        sys.stderr.write("%s: %s\n" %
            (os.path.basename(sys.argv[0]), sys.exc_info()[1]))