string_to_key.c

早期freebsd实现

/*
 * $Source: /afs/athena.mit.edu/astaff/project/kerberos/src/lib/des/RCS/string_to_key.c,v $
 * $Author: jtkohl $
 *
 * Copyright 1985, 1986, 1987, 1988, 1989 by the Massachusetts Institute
 * of Technology.
 *
 * For copying and distribution information, please see the file
 * <mit-copyright.h>.
 *
 * These routines perform encryption and decryption using the DES
 * private key algorithm, or else a subset of it-- fewer inner loops.
 * (AUTH_DES_ITER defaults to 16, may be less.)
 *
 * Under U.S. law, this software may not be exported outside the US
 * without license from the U.S. Commerce department.
 *
 * The key schedule is passed as an arg, as well as the cleartext or
 * ciphertext.  The cleartext and ciphertext should be in host order.
 *
 * These routines form the library interface to the DES facilities.
 *
 *	spm	8/85	MIT project athena
 */

#ifndef	lint
static char rcsid_string_to_key_c[] =
"$Id: string_to_key.c,v 4.11 90/01/02 13:46:38 jtkohl Exp $";
#endif	lint

#include <mit-copyright.h>
#include <stdio.h>
#include <des.h>
#include "des_internal.h"

extern int des_debug;
extern int des_debug_print();
extern void des_fixup_key_parity();

/*
 * convert an arbitrary length string to a DES key
 */
int
des_string_to_key(str,key)
    char *str;
    register des_cblock *key;
{
    register char *in_str;
    register unsigned temp,i;
    register int j;
    register long length;
    static unsigned char *k_p;
    static int forward;
    register char *p_char;
    static char k_char[64];
    static des_key_schedule key_sked;
    extern unsigned long des_cbc_cksum();

    in_str = str;
    forward = 1;
    p_char = k_char;
    length = strlen(str);

    /* init key array for bits */
    bzero(k_char,sizeof(k_char));

#ifdef DEBUG
    if (des_debug)
	fprintf(stdout,
		"\n\ninput str length = %d  string = %s\nstring = 0x ",
		length,str);
#endif

    /* get next 8 bytes, strip parity, xor */
    for (i = 1; i <= length; i++) {
	/* get next input key byte */
	temp = (unsigned int) *str++;
#ifdef DEBUG
	if (des_debug)
	    fprintf(stdout,"%02x ",temp & 0xff);
#endif
	/* loop through bits within byte, ignore parity */
	for (j = 0; j <= 6; j++) {
	    if (forward)
		*p_char++ ^= (int) temp & 01;
	    else
		*--p_char ^= (int) temp & 01;
	    temp = temp >> 1;
	} while (--j > 0);

	/* check and flip direction */
	if ((i%8) == 0)
	    forward = !forward;
    }

    /* now stuff into the key des_cblock, and force odd parity */
    p_char = k_char;
    k_p = (unsigned char *) key;

    for (i = 0; i <= 7; i++) {
	temp = 0;
	for (j = 0; j <= 6; j++)
	    temp |= *p_char++ << (1+j);
	*k_p++ = (unsigned char) temp;
    }

    /* fix key parity */
    des_fixup_key_parity(key);

    /* Now one-way encrypt it with the folded key */
    (void) des_key_sched(key,key_sked);
    (void) des_cbc_cksum((des_cblock *)in_str,key,length,key_sked,key);
    /* erase key_sked */
    bzero((char *)key_sked,sizeof(key_sked));

    /* now fix up key parity again */
    des_fixup_key_parity(key);

    if (des_debug)
	fprintf(stdout,
		"\nResulting string_to_key = 0x%x 0x%x\n",
		*((unsigned long *) key),
		*((unsigned long *) key+1));
}