/* S/KEY v1.1b (skeysubr.c)
 *
 * Authors:
 *          Neil M. Haller <nmh@thumper.bellcore.com>
 *          Philip R. Karn <karn@chicago.qualcomm.com>
 *          John S. Walden <jsw@thumper.bellcore.com>
 *
 * Modifications: 
 *          Scott Chasin <chasin@crimelab.com>
 *
 * S/KEY misc routines.
 *
 * $Id: skeysubr.c,v 1.2 1994/05/24 06:25:27 deraadt Exp $
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <sys/termios.h>

#include "md4.h"
#include "skey.h"

struct termios newtty;
struct termios oldtty;

void trapped();

/* Crunch a key:
 * concatenate the seed and the password, run through MD4 and
 * collapse to 64 bits. This is defined as the user's starting key.
 */
int
keycrunch(result,seed,passwd)
char *result;	/* 8-byte result */
char *seed;	/* Seed, any length */
char *passwd;	/* Password, any length */
{
	char *buf;
	MDstruct md;
	unsigned int buflen;
	int i;
	register long tmp;
	
	buflen = strlen(seed) + strlen(passwd);
	if ((buf = (char *)malloc(buflen+1)) == NULL)
		return -1;
	strcpy(buf,seed);
	strcat(buf,passwd);

	/* Crunch the key through MD4 */
	sevenbit(buf);
	MDbegin(&md);
	MDupdate(&md,(unsigned char *)buf,8*buflen);

	free(buf);

	/* Fold result from 128 to 64 bits */
	md.buffer[0] ^= md.buffer[2];
	md.buffer[1] ^= md.buffer[3];

	/* Default (but slow) code that will convert to
	 * little-endian byte ordering on any machine
	 */
	for (i=0; i<2; i++) {
		tmp = md.buffer[i];
		*result++ = tmp;
		tmp >>= 8;
		*result++ = tmp;
		tmp >>= 8;
		*result++ = tmp;
		tmp >>= 8;
		*result++ = tmp;
	}

	return 0;
}

/* The one-way function f(). Takes 8 bytes and returns 8 bytes in place */
void f (x)
char *x;
{
	MDstruct md;
	register long tmp;

	MDbegin(&md);
	MDupdate(&md,(unsigned char *)x,64);

	/* Fold 128 to 64 bits */
	md.buffer[0] ^= md.buffer[2];
	md.buffer[1] ^= md.buffer[3];

	/* Default (but slow) code that will convert to
	 * little-endian byte ordering on any machine
	 */
	tmp = md.buffer[0];
	*x++ = tmp;
	tmp >>= 8;
	*x++ = tmp;
	tmp >>= 8;
	*x++ = tmp;
	tmp >>= 8;
	*x++ = tmp;

	tmp = md.buffer[1];
	*x++ = tmp;
	tmp >>= 8;
	*x++ = tmp;
	tmp >>= 8;
	*x++ = tmp;
	tmp >>= 8;
	*x = tmp;
}

/* Strip trailing cr/lf from a line of text */
void rip (buf)
char *buf;
{
	char *cp;

	if((cp = strchr(buf,'\r')) != NULL)
		*cp = '\0';

	if((cp = strchr(buf,'\n')) != NULL)
		*cp = '\0';
}

char *readpass (buf,n)
char *buf;
int n;
{
    set_term ();
    echo_off ();

    fgets (buf, n, stdin);

    rip (buf);
    printf ("\n");

    sevenbit (buf);

    unset_term ();
    return buf;
}

set_term () 
{
    fflush(stdout);
    tcgetattr(fileno(stdin), &newtty);
    tcgetattr(fileno(stdin), &oldtty);
 
    signal (SIGINT, trapped);
}

echo_off ()
{
    newtty.c_lflag &= ~(ICANON | ECHO | ECHONL);
    newtty.c_cc[VMIN] = 1;
    newtty.c_cc[VTIME] = 0;
    newtty.c_cc[VINTR] = 3;

    tcsetattr(fileno(stdin), TCSADRAIN, &newtty);
}

unset_term ()
{
    tcsetattr(fileno(stdin), TCSADRAIN, &oldtty);
}

void trapped()
 {
  signal (SIGINT, trapped);
  printf ("^C\n");
  unset_term ();
  exit (-1);
 }

/* removebackspaced over charaters from the string */
backspace(buf)
char *buf;
{
	char bs = 0x8;
	char *cp = buf;
	char *out = buf;

	while(*cp){
		if( *cp == bs ) {
			if(out == buf){
				cp++;
				continue;
			}
			else {
			  cp++;
			  out--;
			}
		}
		else {
			*out++ = *cp++;
		}

	}
	*out = '\0';
	
}

/* sevenbit ()
 *
 * Make sure line is all seven bits.
 */
 
sevenbit (s)
char *s;
{
   while (*s) {
     *s = 0x7f & ( *s);
     s++;
   }
}