random.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

#ifndef lint
static	char	*sccsid = "@(#)random.c	4.1	(ULTRIX)	7/17/90";
#endif lint

/************************************************************************
 *									*
 *			Copyright (c) 1988, 1989 by			*
 *		Digital Equipment Corporation, Maynard, MA		*
 *			All rights reserved.				*
 *									*
 *   This software is furnished under a license and may be used and	*
 *   copied  only  in accordance with the terms of such license and	*
 *   with the  inclusion  of  the  above  copyright  notice.   This	*
 *   software  or  any  other copies thereof may not be provided or	*
 *   otherwise made available to any other person.  No title to and	*
 *   ownership of the software is hereby transferred.			*
 *									*
 *   The information in this software is subject to change  without	*
 *   notice  and should not be construed as a commitment by Digital	*
 *   Equipment Corporation.						*
 *									*
 *   Digital assumes no responsibility for the use  or  reliability	*
 *   of its software on equipment which is not supplied by Digital.	*
 *									*
 ************************************************************************/
/*
 * Modification History:
 *
 * 22 June 1989 - D. Long
 *	Removed call to setkey() by putting most of crypt.c inline.
 *
 * Created:
 * 7 June, 1989 D. Long
 */
/*
 * This module uses the DES encryption algorithm to implement
 * a pseudo-random number generator.
 */

#ifdef CRYPT
/*
 * Initial permutation,
 */
#endif CRYPT
static	char	IP[] = {
	58,50,42,34,26,18,10, 2,
	60,52,44,36,28,20,12, 4,
	62,54,46,38,30,22,14, 6,
	64,56,48,40,32,24,16, 8,
	57,49,41,33,25,17, 9, 1,
	59,51,43,35,27,19,11, 3,
	61,53,45,37,29,21,13, 5,
	63,55,47,39,31,23,15, 7,
};

#ifdef CRYPT
/*
 * Final permutation, FP = IP^(-1)
 */
#endif CRYPT
static	char	FP[] = {
	40, 8,48,16,56,24,64,32,
	39, 7,47,15,55,23,63,31,
	38, 6,46,14,54,22,62,30,
	37, 5,45,13,53,21,61,29,
	36, 4,44,12,52,20,60,28,
	35, 3,43,11,51,19,59,27,
	34, 2,42,10,50,18,58,26,
	33, 1,41, 9,49,17,57,25,
};

#ifdef CRYPT
/*
 * Permuted-choice 1 from the key bits
 * to yield C and D.
 * Note that bits 8,16... are left out:
 * They are intended for a parity check.
 */
#endif CRYPT
static	char	PC1_C[] = {
	57,49,41,33,25,17, 9,
	 1,58,50,42,34,26,18,
	10, 2,59,51,43,35,27,
	19,11, 3,60,52,44,36,
};

static	char	PC1_D[] = {
	63,55,47,39,31,23,15,
	 7,62,54,46,38,30,22,
	14, 6,61,53,45,37,29,
	21,13, 5,28,20,12, 4,
};

#ifdef CRYPT
/*
 * Sequence of shifts used for the key schedule.
*/
#endif CRYPT
static	char	shifts[] = {
	1,1,2,2,2,2,2,2,1,2,2,2,2,2,2,1,
};

#ifdef CRYPT
/*
 * Permuted-choice 2, to pick out the bits from
 * the CD array that generate the key schedule.
 */
#endif CRYPT
static	char	PC2_C[] = {
	14,17,11,24, 1, 5,
	 3,28,15, 6,21,10,
	23,19,12, 4,26, 8,
	16, 7,27,20,13, 2,
};

static	char	PC2_D[] = {
	41,52,31,37,47,55,
	30,40,51,45,33,48,
	44,49,39,56,34,53,
	46,42,50,36,29,32,
};

#ifdef CRYPT
/*
 * The C and D arrays used to calculate the key schedule.
 */

#endif CRYPT
static	char	C[28];
static	char	D[28];
#ifdef CRYPT
/*
 * The key schedule.
 * Generated from the key.
 */
#endif CRYPT
static	char	KS[16][48];

#ifdef CRYPT
/*
 * The E bit-selection table.
 */
#endif CRYPT
static	char	E[48];
static	char	e[] = {
	32, 1, 2, 3, 4, 5,
	 4, 5, 6, 7, 8, 9,
	 8, 9,10,11,12,13,
	12,13,14,15,16,17,
	16,17,18,19,20,21,
	20,21,22,23,24,25,
	24,25,26,27,28,29,
	28,29,30,31,32, 1,
};

#ifdef CRYPT
/*
 * The 8 selection functions.
 * For some reason, they give a 0-origin
 * index, unlike everything else.
 */
#endif CRYPT
static	char	S[8][64] = {
	14, 4,13, 1, 2,15,11, 8, 3,10, 6,12, 5, 9, 0, 7,
	 0,15, 7, 4,14, 2,13, 1,10, 6,12,11, 9, 5, 3, 8,
	 4, 1,14, 8,13, 6, 2,11,15,12, 9, 7, 3,10, 5, 0,
	15,12, 8, 2, 4, 9, 1, 7, 5,11, 3,14,10, 0, 6,13,

	15, 1, 8,14, 6,11, 3, 4, 9, 7, 2,13,12, 0, 5,10,
	 3,13, 4, 7,15, 2, 8,14,12, 0, 1,10, 6, 9,11, 5,
	 0,14, 7,11,10, 4,13, 1, 5, 8,12, 6, 9, 3, 2,15,
	13, 8,10, 1, 3,15, 4, 2,11, 6, 7,12, 0, 5,14, 9,

	10, 0, 9,14, 6, 3,15, 5, 1,13,12, 7,11, 4, 2, 8,
	13, 7, 0, 9, 3, 4, 6,10, 2, 8, 5,14,12,11,15, 1,
	13, 6, 4, 9, 8,15, 3, 0,11, 1, 2,12, 5,10,14, 7,
	 1,10,13, 0, 6, 9, 8, 7, 4,15,14, 3,11, 5, 2,12,

	 7,13,14, 3, 0, 6, 9,10, 1, 2, 8, 5,11,12, 4,15,
	13, 8,11, 5, 6,15, 0, 3, 4, 7, 2,12, 1,10,14, 9,
	10, 6, 9, 0,12,11, 7,13,15, 1, 3,14, 5, 2, 8, 4,
	 3,15, 0, 6,10, 1,13, 8, 9, 4, 5,11,12, 7, 2,14,

	 2,12, 4, 1, 7,10,11, 6, 8, 5, 3,15,13, 0,14, 9,
	14,11, 2,12, 4, 7,13, 1, 5, 0,15,10, 3, 9, 8, 6,
	 4, 2, 1,11,10,13, 7, 8,15, 9,12, 5, 6, 3, 0,14,
	11, 8,12, 7, 1,14, 2,13, 6,15, 0, 9,10, 4, 5, 3,

	12, 1,10,15, 9, 2, 6, 8, 0,13, 3, 4,14, 7, 5,11,
	10,15, 4, 2, 7,12, 9, 5, 6, 1,13,14, 0,11, 3, 8,
	 9,14,15, 5, 2, 8,12, 3, 7, 0, 4,10, 1,13,11, 6,
	 4, 3, 2,12, 9, 5,15,10,11,14, 1, 7, 6, 0, 8,13,

	 4,11, 2,14,15, 0, 8,13, 3,12, 9, 7, 5,10, 6, 1,
	13, 0,11, 7, 4, 9, 1,10,14, 3, 5,12, 2,15, 8, 6,
	 1, 4,11,13,12, 3, 7,14,10,15, 6, 8, 0, 5, 9, 2,
	 6,11,13, 8, 1, 4,10, 7, 9, 5, 0,15,14, 2, 3,12,

	13, 2, 8, 4, 6,15,11, 1,10, 9, 3,14, 5, 0,12, 7,
	 1,15,13, 8,10, 3, 7, 4,12, 5, 6,11, 0,14, 9, 2,
	 7,11, 4, 1, 9,12,14, 2, 0, 6,10,13,15, 3, 5, 8,
	 2, 1,14, 7, 4,10, 8,13,15,12, 9, 0, 3, 5, 6,11,
};

#ifdef CRYPT
/*
 * P is a permutation on the selected combination
 * of the current L and key.
 */
#endif CRYPT
static	char	P[] = {
	16, 7,20,21,
	29,12,28,17,
	 1,15,23,26,
	 5,18,31,10,
	 2, 8,24,14,
	32,27, 3, 9,
	19,13,30, 6,
	22,11, 4,25,
};

#ifdef CRYPT
/*
 * The current block, divided into 2 halves.
 */
#endif CRYPT
static	char	L[32], R[32];
static	char	tempL[32];
static	char	f[32];

#ifdef CRYPT
/*
 * The combination of the key and the input, before selection.
 */
#endif CRYPT
static	char	preS[48];

static encrypt(block)
char *block;
{
	int i;
	register t, j, k;

#ifdef CRYPT
	/*
	 * First, permute the bits in the input
	 */
#endif CRYPT
	for (j=0; j<64; j++)
		L[j] = block[IP[j]-1];
	for(i=0; i < 16; i++) {
		for (j=0; j<32; j++)
			tempL[j] = R[j];
#ifdef CRYPT
		/*
		 * Expand R to 48 bits using the E selector;
		 * exclusive-or with the current key bits.
		 */
#endif CRYPT
		for (j=0; j<48; j++)
			preS[j] = R[E[j]-1] ^ KS[i][j];
#ifdef CRYPT
		/*
		 * The pre-select bits are now considered
		 * in 8 groups of 6 bits each.
		 * The 8 selection functions map these
		 * 6-bit quantities into 4-bit quantities
		 * and the results permuted
		 * to make an f(R, K).
		 * The indexing into the selection functions
		 * is peculiar; it could be simplified by
		 * rewriting the tables.
		 */
#endif CRYPT
		for (j=0; j<8; j++) {
			t = 6*j;
			k = S[j][(preS[t+0]<<5)+
				(preS[t+1]<<3)+
				(preS[t+2]<<2)+
				(preS[t+3]<<1)+
				(preS[t+4]<<0)+
				(preS[t+5]<<4)];
			t = 4*j;
			f[t+0] = (k>>3)&01;
			f[t+1] = (k>>2)&01;
			f[t+2] = (k>>1)&01;
			f[t+3] = (k>>0)&01;
		}
#ifdef CRYPT
		/*
		 * The new R is L ^ f(R, K).
		 * The f here has to be permuted first, though.
		 */
#endif CRYPT
		for (j=0; j<32; j++)
			R[j] = L[j] ^ f[P[j]-1];
#ifdef CRYPT
		/*
		 * Finally, the new L (the original R)
		 * is copied back.
		 */
#endif CRYPT
		for (j=0; j<32; j++)
			L[j] = tempL[j];
	}
#ifdef CRYPT
	/*
	 * The output L and R are reversed.
	 */
#endif CRYPT
	for (j=0; j<32; j++) {
		t = L[j];
		L[j] = R[j];
		R[j] = t;
	}
#ifdef CRYPT
	/*
	 * The final output
	 * gets the inverse permutation of the very original.
	 */
#endif CRYPT
	for (j=0; j<64; j++)
		block[j] = L[FP[j]-1];
}

static expand(in, out)
register char *in, *out;
{
	register int j, c;
	int i;

	for(i=0; (c = *in) && i<64; in++){
		for(j=6; j >= 0; j--)
			*out++ = (c>>j) & 01;
		*out++ = 0;
		i += 8;
	}
	for(j=i; j < 64; j++)
		*out++ = 0;
}

static perturb(pw,salt)
char *pw;
char *salt;
{
	register i, j, c, k;
	int	t, temp;
	static char block[66], iobuf[16];

/*
	expand(pw, block);

	for (i=0; i<28; i++) {
		C[i] = block[PC1_C[i]-1];
		D[i] = block[PC1_D[i]-1];
	}
	for (i=0; i<16; i++) {
		for (k=0; k<shifts[i]; k++) {
			t = C[0];
			for (j=0; j<28-1; j++)
				C[j] = C[j+1];
			C[27] = t;
			t = D[0];
			for (j=0; j<28-1; j++)
				D[j] = D[j+1];
			D[27] = t;
		}
		for (j=0; j<24; j++) {
			KS[i][j] = C[PC2_C[j]-1];
			KS[i][j+24] = D[PC2_D[j]-28-1];
		}
	}

*/
	for(i=0;i<48;i++)
		E[i] = e[i];

	for(i=0;i<2;i++){
		c = *salt++;
		iobuf[i] = c;
		if(c>'Z') c -= 6;
		if(c>'9') c -= 7;
		c -= '.';
		for(j=0;j<6;j++){
			if((c>>j) & 01){
				temp = E[6*i+j];
				E[6*i+j] = E[6*i+j+24];
				E[6*i+j+24] = temp;
				}
			}
		}
}

static unsigned char seed[64], block[64];
randseed(s)
char *s;
{
	int i, j, bit=0, x, c;
	char salt[3];
	static char salt_table[] =
	    "abcdefghijklmnopqrstuvwxyz9876543210ABCDEFGHIJKLMNOPQRSTUVWXYZ./";

	salt[0] = salt_table[s[0]&077];
	salt[1] = salt_table[s[1]&077];
	salt[2] = '\0';
	perturb("12345678", salt);
	for(j=2; j < 10; j++) {
		c = s[j];
		for(i=0; i < 8; i++) {
			seed[bit++] = c & 1;
			c >>= 1;
		}
	}
/*
	setkey(seed);
*/
#ifdef CRYPT
/*
 * Set up the key schedule from the key.
 */
#endif
	{
	register i, j, k;
	int t;

#ifdef	CRYPT
	/*
	 * First, generate C and D by permuting
	 * the key.  The low order bit of each
	 * 8-bit char is not used, so C and D are only 28
	 * bits apiece.
	 */
#endif
	for (i=0; i<28; i++) {
		C[i] = seed[PC1_C[i]-1];
		D[i] = seed[PC1_D[i]-1];
	}
#ifdef	CRYPT
	/*
	 * To generate Ki, rotate C and D according
	 * to schedule and pick up a permutation
	 * using PC2.
	 */
#endif
	for (i=0; i<16; i++) {
#ifdef	CRYPT
		/*
		 * rotate.
		 */
#endif
		for (k=0; k<shifts[i]; k++) {
			t = C[0];
			for (j=0; j<28-1; j++)
				C[j] = C[j+1];
			C[27] = t;
			t = D[0];
			for (j=0; j<28-1; j++)
				D[j] = D[j+1];
			D[27] = t;
		}
#ifdef	CRYPT
		/*
		 * get Ki. Note C and D are concatenated.
		 */
#endif
		for (j=0; j<24; j++) {
			KS[i][j] = C[PC2_C[j]-1];
			KS[i][j+24] = D[PC2_D[j]-28-1];
		}
	}
	}
	for(j=10; j < 18; j++) {
		c = s[j];
		for(i=0; i < 8 ; i++) {
			block[bit++] = c & 1;
			c >>= 1;
		}
	}
}

int  get_random (min, max)
register int  min, max;
{
/*
    return (min + (unsigned short int) randint ((int) (max - min + 1)));
	return (unsigned short)(min+(random()/(((unsigned) 2147483648)/((unsigned)(max-min+1)))));
*/
	int i;
	unsigned long x=0;

	encrypt(block);
	for(i=0; i < 31; i++)
		x = (x<<1) | block[i];
	x = (min+(x/(((unsigned long) 0x80000000)/((unsigned)(max-min+1)))));
	return x;
}