/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
/*	  All Rights Reserved  	*/


/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 *	A one-rotor machine designed along the lines of Enigma
 *	but considerably trivialized.
 */

#define	ECHO 010
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <crypt.h>
#include <errno.h>

#define	ROTORSZ 256
#define	MASK 0377
char	t1[ROTORSZ];
char	t2[ROTORSZ];
char	t3[ROTORSZ];

static void
setup(pw)
char *pw;
{
	int ic, i, k, temp;
	unsigned random;
	char buf[13];
	long seed;
	char *ret;
	int err;

	(void) strncpy(buf, pw, 8);
	buf[8] = buf[0];
	buf[9] = buf[1];
	errno = 0;
	ret = des_crypt(buf, &buf[8]);
	if (ret == NULL) {
		err = errno;
		(void) fprintf(stderr, "crypt: setup failed, unable to"
		    " initialize rotors: %s\n", strerror(err));
		exit(1);
	}
	(void) strncpy(buf, ret, 13);
	seed = 123;
	for (i = 0; i < 13; i++)
		seed = seed*buf[i] + i;
	for (i = 0; i < ROTORSZ; i++) {
		t1[i] = i;
		t3[i] = 0;
	}
	for (i = 0; i < ROTORSZ; i++) {
		seed = 5*seed + buf[i%13];
		random = seed % 65521;
		k = ROTORSZ-1 - i;
		ic = (random&MASK)%(k+1);
		random >>= 8;
		temp = t1[k];
		t1[k] = t1[ic];
		t1[ic] = temp;
		if (t3[k] != 0) continue;
		ic = (random&MASK) % k;
		while (t3[ic] != 0) ic = (ic+1) % k;
		t3[k] = ic;
		t3[ic] = k;
	}
	for (i = 0; i < ROTORSZ; i++)
		t2[t1[i]&MASK] = i;
}

int
main(int argc, char **argv)
{
	extern int optind;
	char *p1;
	int i, n1, n2, nchar;
	int c;
	struct {
		long offset;
		unsigned int count;
	} header;
	int pflag = 0;
	int kflag = 0;
	char *buf;
	char key[8];
	char keyvar[] = "CrYpTkEy=XXXXXXXX";
	char *s;

	if (argc < 2) {
		if ((buf = (char *)getpass("Enter key:")) == NULL) {
			(void) fprintf(stderr, "Cannot open /dev/tty\n");
			exit(1);
		}
		setup(buf);
	} else {
		while ((c = getopt(argc, argv, "pk")) != EOF)
			switch (c) {
			case 'p':
			/* notify editor that exec has succeeded */
				if (write(1, "y", 1) != 1)
					exit(1);
				if (read(0, key, 8) != 8)
					exit(1);
				setup(key);
				pflag = 1;
				break;
			case 'k':
				if ((s = getenv("CrYpTkEy")) == (char *)NULL) {
					(void) fprintf(stderr,
					    "CrYpTkEy not set.\n");
					exit(1);
				}
				(void) strncpy(key, s, 8);
				setup(key);
				kflag = 1;
				break;
			case '?':
				(void) fprintf(stderr,
				    "usage: crypt [ -k ] [ key]\n");
				exit(2);
			}
		if (pflag == 0 && kflag == 0) {
			(void) strncpy(keyvar+9, argv[optind], 8);
			(void) putenv(keyvar);
			(void) execlp("crypt", "crypt", "-k", 0);
		}
	}
	if (pflag)
		for (;;) {
			if ((nchar = read(0, (char *)&header, sizeof (header)))
			    != sizeof (header))
				exit(nchar);
			n1 = (int)(header.offset&MASK);
			n2 = (int)((header.offset >> 8) &MASK);
			nchar = header.count;
			buf = (char *)malloc(nchar);
			p1 = buf;
			if (read(0, buf, nchar) != nchar)
				exit(1);
			while (nchar--) {
				*p1 = t2[(t3[(t1[(*p1 + n1)&MASK]+
				    n2)&MASK] - n2)&MASK] - n1;
				n1++;
				if (n1 == ROTORSZ) {
					n1 = 0;
					n2++;
					if (n2 == ROTORSZ) n2 = 0;
				}
				p1++;
			}
			nchar = header.count;
			if (write(1, buf, nchar) != nchar)
				exit(1);
			free(buf);
		}

	n1 = 0;
	n2 = 0;

	while ((i = getchar()) >= 0) {
		i = t2[(t3[(t1[(i+n1)&MASK]+n2)&MASK]-n2)&MASK]-n1;
		(void) putchar(i);
		n1++;
		if (n1 == ROTORSZ) {
			n1 = 0;
			n2++;
			if (n2 == ROTORSZ) n2 = 0;
		}
	}
	return (0);
}