93 lines
2.0 KiB
C
93 lines
2.0 KiB
C
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/* Generic xor handler.
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With no args, xors stdin against 0xFF to stdout. A single argument is a
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file to read xor-bytes out of. Any zero in the xor-bytes array is treated
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as the end; if you need to xor against a string that *includes* zeros,
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you're on your own.
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The indirect file can be generated easily with data.c.
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Written because there are so many lame schemes for "masking" plaintext
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passwords and the like floating around, and it's handy to just run an
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obscure binary-format configuration file through this and look for strings.
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*Hobbit*, 960208 */
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#include <stdio.h>
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#include <fcntl.h>
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char buf[8192];
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char bytes[256];
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char * py;
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/* do the xor, in place. Uses global ptr "py" to maintain "bytes" state */
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xorb (buf, len)
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char * buf;
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int len;
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{
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register int x;
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register char * pb;
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pb = buf;
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x = len;
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while (x > 0) {
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*pb = (*pb ^ *py);
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pb++;
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py++;
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if (! *py)
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py = bytes;
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x--;
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}
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} /* xorb */
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/* blah */
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main (argc, argv)
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int argc;
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char ** argv;
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{
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register int x = 0;
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register int y;
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/* manually preload; xor-with-0xFF is all too common */
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memset (bytes, 0, sizeof (bytes));
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bytes[0] = 0xff;
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/* if file named in any arg, reload from that */
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#ifdef O_BINARY /* DOS shit... */
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x = setmode (0, O_BINARY); /* make stdin raw */
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if (x < 0) {
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fprintf (stderr, "stdin binary setmode oops: %d\n", x);
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exit (1);
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}
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x = setmode (1, O_BINARY); /* make stdout raw */
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if (x < 0) {
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fprintf (stderr, "stdout binary setmode oops: %d\n", x);
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exit (1);
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}
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#endif /* O_BINARY */
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if (argv[1])
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#ifdef O_BINARY
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x = open (argv[1], O_RDONLY | O_BINARY);
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#else
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x = open (argv[1], O_RDONLY);
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#endif
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if (x > 0) {
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read (x, bytes, 250); /* nothin' fancy here */
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close (x);
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}
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py = bytes;
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x = 1;
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while (x > 0) {
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x = read (0, buf, sizeof (buf));
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if (x <= 0)
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break;
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xorb (buf, x);
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y = write (1, buf, x);
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if (y <= 0)
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exit (1);
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}
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exit (0);
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}
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