set_key.c

Netscape公司提供的安全套接字层

/* set_key.c */
/* Copyright (C) 1993 Eric Young - see README for more details */
/* set_key.c v 1.4 eay 24/9/91
 * 1.4 Speed up by 400% :-)
 * 1.3 added register declarations.
 * 1.2 unrolled make_key_sched a bit more
 * 1.1 added norm_expand_bits
 * 1.0 First working version
 */
#include "des_locl.h"
#include "podd.h"
#include "sk.h"

static int check_parity();

int des_check_key=0;

void des_set_odd_parity(key)
des_cblock *key;
    {
    int i;

    for (i=0; i<DES_KEY_SZ; i++)
        (*key)[i]=odd_parity[(*key)[i]];
    }

static int check_parity(key)
des_cblock *key;
    {
    int i;

    for (i=0; i<DES_KEY_SZ; i++)
        {
        if ((*key)[i] != odd_parity[(*key)[i]])
            return(0);
        }
    return(1);
    }

/* Weak and semi week keys as take from
 * %A D.W. Davies
 * %A W.L. Price
 * %T Security for Computer Networks
 * %I John Wiley & Sons
 * %D 1984
 * Many thanks to [e-mail] (Steven Bellovin) for the reference
 * (and actual cblock values).
 */
#define NUM_WEAK_KEY    16
static des_cblock weak_keys[NUM_WEAK_KEY]={
    /* weak keys */
    0x01,0x01,0x01,0x01,0x01,0x01,0x01,0x01,
    0xFE,0xFE,0xFE,0xFE,0xFE,0xFE,0xFE,0xFE,
    0x1F,0x1F,0x1F,0x1F,0x1F,0x1F,0x1F,0x1F,
    0xE0,0xE0,0xE0,0xE0,0xE0,0xE0,0xE0,0xE0,
    /* semi-weak keys */
    0x01,0xFE,0x01,0xFE,0x01,0xFE,0x01,0xFE,
    0xFE,0x01,0xFE,0x01,0xFE,0x01,0xFE,0x01,
    0x1F,0xE0,0x1F,0xE0,0x0E,0xF1,0x0E,0xF1,
    0xE0,0x1F,0xE0,0x1F,0xF1,0x0E,0xF1,0x0E,
    0x01,0xE0,0x01,0xE0,0x01,0xF1,0x01,0xF1,
    0xE0,0x01,0xE0,0x01,0xF1,0x01,0xF1,0x01,
    0x1F,0xFE,0x1F,0xFE,0x0E,0xFE,0x0E,0xFE,
    0xFE,0x1F,0xFE,0x1F,0xFE,0x0E,0xFE,0x0E,
    0x01,0x1F,0x01,0x1F,0x01,0x0E,0x01,0x0E,
    0x1F,0x01,0x1F,0x01,0x0E,0x01,0x0E,0x01,
    0xE0,0xFE,0xE0,0xFE,0xF1,0xFE,0xF1,0xFE,
    0xFE,0xE0,0xFE,0xE0,0xFE,0xF1,0xFE,0xF1};

int des_is_weak_key(key)
des_cblock *key;
    {
    int i;

    for (i=0; i<NUM_WEAK_KEY; i++)
        /* Added == 0 to comparision, I obviously don't run
         * this section very often :-(, thanks to
         * [e-mail] for the fix
         * eay 93/06/29 */
        if (memcmp(weak_keys[i],key,sizeof(key)) == 0) return(1);
    return(0);
    }

/* NOW DEFINED IN des_local.h
 * See ecb_encrypt.c for a pseudo description of these macros. 
 * #define PERM_OP(a,b,t,n,m) ((t)=((((a)>>(n))^(b))&(m)),\
 *  (b)^=(t),\
 *  (a)=((a)^((t)<<(n))))
 */

#define HPERM_OP(a,t,n,m) ((t)=((((a)<<(16-(n)))^(a))&(m)),\
    (a)=(a)^(t)^(t>>(16-(n))))

static char shifts2[16]={0,0,1,1,1,1,1,1,0,1,1,1,1,1,1,0};

/* return 0 if key parity is odd (correct),
 * return -1 if key parity error,
 * return -2 if illegal weak key.
 */
int des_set_key(key,schedule)
des_cblock *key;
des_key_schedule schedule;
    {
    register unsigned long c,d,t,s;
    register unsigned char *in;
    register unsigned long *k;
    register int i;

    if (des_check_key)
        {
        if (!check_parity(key))
            return(-1);

        if (des_is_weak_key(key))
            return(-2);
        }

    k=(unsigned long *)schedule;
    in=(unsigned char *)key;

    c2l(in,c);
    c2l(in,d);

    /* do PC1 in 60 simple operations */ 
/*  PERM_OP(d,c,t,4,0x0f0f0f0f);
    HPERM_OP(c,t,-2, 0xcccc0000);
    HPERM_OP(c,t,-1, 0xaaaa0000);
    HPERM_OP(c,t, 8, 0x00ff0000);
    HPERM_OP(c,t,-1, 0xaaaa0000);
    HPERM_OP(d,t,-8, 0xff000000);
    HPERM_OP(d,t, 8, 0x00ff0000);
    HPERM_OP(d,t, 2, 0x33330000);
    d=((d&0x00aa00aa)<<7)|((d&0x55005500)>>7)|(d&0xaa55aa55);
    d=(d>>8)|((c&0xf0000000)>>4);
    c&=0x0fffffff; */

    /* I now do it in 47 simple operations :-)
     * Thanks to John Fletcher ([e-mail])
     * for the inspiration. :-) */
    PERM_OP (d,c,t,4,0x0f0f0f0f);
    HPERM_OP(c,t,-2,0xcccc0000);
    HPERM_OP(d,t,-2,0xcccc0000);
    PERM_OP (d,c,t,1,0x55555555);
    PERM_OP (c,d,t,8,0x00ff00ff);
    PERM_OP (d,c,t,1,0x55555555);
    d=  (((d&0x000000ff)<<16)| (d&0x0000ff00)     |
         ((d&0x00ff0000)>>16)|((c&0xf0000000)>>4));
    c&=0x0fffffff;

    for (i=0; i<ITERATIONS; i++)
        {
        if (shifts2[i])
            { c=((c>>2)|(c<<26)); d=((d>>2)|(d<<26)); }
        else
            { c=((c>>1)|(c<<27)); d=((d>>1)|(d<<27)); }
        c&=0x0fffffff;
        d&=0x0fffffff;
        /* could be a few less shifts but I am to lazy at this
         * point in time to investigate */
        s=  des_skb[0][ (c    )&0x3f                ]|
            des_skb[1][((c>> 6)&0x03)|((c>> 7)&0x3c)]|
            des_skb[2][((c>>13)&0x0f)|((c>>14)&0x30)]|
            des_skb[3][((c>>20)&0x01)|((c>>21)&0x06) |
                          ((c>>22)&0x38)];
        t=  des_skb[4][ (d    )&0x3f                ]|
            des_skb[5][((d>> 7)&0x03)|((d>> 8)&0x3c)]|
            des_skb[6][ (d>>15)&0x3f                ]|
            des_skb[7][((d>>21)&0x0f)|((d>>22)&0x30)];

        /* table contained 0213 4657 */
        *(k++)=((t<<16)|(s&0x0000ffff))&0xffffffff;
        s=     ((s>>16)|(t&0xffff0000));
        
        s=(s<<4)|(s>>28);
        *(k++)=s&0xffffffff;
        }
    return(0);
    }

int des_key_sched(key,schedule)
des_cblock *key;
des_key_schedule schedule;
    {
    return(des_set_key(key,schedule));
    }