path: root/src/desCalculator/des.c

/* Sofware DES functions
 * written 12 Dec 1986 by Phil Karn, KA9Q; large sections adapted from
 * the 1977 public-domain program by Jim Gillogly
 * Modified for additional speed - 6 December 1988 Phil Karn
 * Modified for parameterized key schedules - Jan 1991 Phil Karn
 * Callers now allocate a key schedule as follows:
 *	kn = (char (*)[8])malloc(sizeof(char) * 8 * 16);
 *	or
 *	char kn[16][8];
 */

/* modified in order to use the libmcrypt API by Nikos Mavroyanopoulos 
 * All modifications are placed under the license of libmcrypt.
 */

/* $Id: des.c,v 1.13 2003/01/19 17:48:27 nmav Exp $ */

#include "des.h"

/* #define	NULL	0 */

static void permute_ip(), permute_fp(), perminit_ip(), spinit(),
perminit_fp();
static uint32_t f();


/* Tables defined in the Data Encryption Standard documents */

/* initial permutation IP */
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
};

/* final permutation IP^-1 */
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
};

/* expansion operation matrix
 * This is for reference only; it is unused in the code
 * as the f() function performs it implicitly for speed
 */
#ifdef notdef
static char ei[] = {
	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
};
#endif

/* permuted choice table (key) */
static char pc1[] = {
	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,

	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
};

/* number left rotations of pc1 */
static char totrot[] = {
	1, 2, 4, 6, 8, 10, 12, 14, 15, 17, 19, 21, 23, 25, 27, 28
};

/* permuted choice key (table) */
static char pc2[] = {
	14, 17, 11, 24, 1, 5,
	3, 28, 15, 6, 21, 10,
	23, 19, 12, 4, 26, 8,
	16, 7, 27, 20, 13, 2,
	41, 52, 31, 37, 47, 55,
	30, 40, 51, 45, 33, 48,
	44, 49, 39, 56, 34, 53,
	46, 42, 50, 36, 29, 32
};

/* The (in)famous S-boxes */
static char si[8][64] = {
	/* S1 */
	{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},

	/* S2 */
	{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},

	/* S3 */
	{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},

	/* S4 */
	{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},

	/* S5 */
	{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},

	/* S6 */
	{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},

	/* S7 */
	{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},

	/* S8 */
	{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},

};

/* 32-bit permutation function P used on the output of the S-boxes */
static char p32i[] = {
	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
};

/* End of DES-defined tables */

/* Lookup tables initialized once only at startup by desinit() */

/* bit 0 is left-most in byte */
static int bytebit[] = {
	0200, 0100, 040, 020, 010, 04, 02, 01
};

static int nibblebit[] = {
	010, 04, 02, 01
};

/* Allocate space and initialize DES lookup arrays
 * mode == 0: standard Data Encryption Algorithm
 */
static int _mcrypt_desinit(DES_KEY * key)
{

	spinit(key);
	perminit_ip(key);
	perminit_fp(key);

	return 0;
}


/* Set key (initialize key schedule array) */
int _mcrypt_set_key(DES_KEY * dkey, char *user_key, int len)
{
	char pc1m[56];		/* place to modify pc1 into */
	char pcr[56];		/* place to rotate pc1 into */
	register int i, j, l;
	int m;

	Bzero(dkey, sizeof(DES_KEY));
	_mcrypt_desinit(dkey);

	/* Clear key schedule */


	for (j = 0; j < 56; j++) {	/* convert pc1 to bits of key */
		l = pc1[j] - 1;	/* integer bit location  */
		m = l & 07;	/* find bit              */
		pc1m[j] = (user_key[l >> 3] &	/* find which key byte l is in */
			   bytebit[m])	/* and which bit of that byte */
		    ? 1 : 0;	/* and store 1-bit result */

	}
	for (i = 0; i < 16; i++) {	/* key chunk for each iteration */
		for (j = 0; j < 56; j++)	/* rotate pc1 the right amount */
			pcr[j] =
			    pc1m[(l = j + totrot[i]) <
				 (j < 28 ? 28 : 56) ? l : l - 28];
		/* rotate left and right halves independently */
		for (j = 0; j < 48; j++) {	/* select bits individually */
			/* check bit that goes to kn[j] */
			if (pcr[pc2[j] - 1]) {
				/* mask it in if it's there */
				l = j % 6;
				dkey->kn[i][j / 6] |= bytebit[l] >> 2;
			}
		}
	}
	return 0;
}

/* In-place encryption of 64-bit block */
void _mcrypt_encrypt(DES_KEY * key, char *block)
{
	uint32_t strings[20];

	register uint32_t left, right;
	register char *knp;
	uint32_t work[2];		/* Working data storage */

	strings[0] = 0x8080CAA3;
	permute_ip(block, key, (char *) work);	/* Initial Permutation */
#ifndef	WORDS_BIGENDIAN
	left = byteswap32(work[0]);
	right = byteswap32(work[1]);
#else
	left = work[0];
	right = work[1];
#endif

	strings[1] = 0x83F5EF93;
	/* Do the 16 rounds.
	 * The rounds are numbered from 0 to 15. On even rounds
	 * the right half is fed to f() and the result exclusive-ORs
	 * the left half; on odd rounds the reverse is done.
	 */
	knp = &key->kn[0][0];
	strings[3] = 0xF5C58BFF;
	left ^= f(key, right, knp);
	knp += 8;
	strings[2] = 0xE5EF9A9C;
	right ^= f(key, left, knp);
	printf("des_intermediate_value = [0x%X, 0x%X]\n", left, right);
	knp += 8;
	left ^= f(key, right, knp);
	knp += 8;
	right ^= f(key, left, knp);
	knp += 8;
	left ^= f(key, right, knp);
	knp += 8;
	right ^= f(key, left, knp);
	knp += 8;
	left ^= f(key, right, knp);
	knp += 8;
	right ^= f(key, left, knp);
	knp += 8;
	left ^= f(key, right, knp);
	knp += 8;
	right ^= f(key, left, knp);
	knp += 8;
	left ^= f(key, right, knp);
	knp += 8;
	right ^= f(key, left, knp);
	knp += 8;
	left ^= f(key, right, knp);
	knp += 8;
	right ^= f(key, left, knp);
	knp += 8;
	left ^= f(key, right, knp);
	knp += 8;
	right ^= f(key, left, knp);

	/* Left/right half swap, plus byte swap if little-endian */
#ifndef	WORDS_BIGENDIAN
	work[1] = byteswap32(left);
	work[0] = byteswap32(right);
#else
	work[0] = right;
	work[1] = left;
#endif
	permute_fp((char *) work, key, block);	/* Inverse initial permutation */
}

/* Permute inblock with perm */
static void permute_ip(char *inblock, DES_KEY * key, char *outblock)
{
	register char *ib, *ob;	/* ptr to input or output block */
	register char *p, *q;
	register int j;

	/* Clear output block */
	Bzero(outblock, 8);

	ib = inblock;
	for (j = 0; j < 16; j += 2, ib++) {	/* for each input nibble */
		ob = outblock;
		p = key->iperm[j][(*ib >> 4) & 0xf];
		q = key->iperm[j + 1][*ib & 0xf];
		/* and each output byte, OR the masks together */
		*ob++ |= *p++ | *q++;
		*ob++ |= *p++ | *q++;
		*ob++ |= *p++ | *q++;
		*ob++ |= *p++ | *q++;
		*ob++ |= *p++ | *q++;
		*ob++ |= *p++ | *q++;
		*ob++ |= *p++ | *q++;
		*ob++ |= *p++ | *q++;
	}
}

/* Permute inblock with perm */
static void permute_fp(char *inblock, DES_KEY * key, char *outblock)
{
	register char *ib, *ob;	/* ptr to input or output block */
	register char *p, *q;
	register int j;

	/* Clear output block */
	Bzero(outblock, 8);

	ib = inblock;
	for (j = 0; j < 16; j += 2, ib++) {	/* for each input nibble */
		ob = outblock;
		p = key->fperm[j][(*ib >> 4) & 0xf];
		q = key->fperm[j + 1][*ib & 0xf];
		/* and each output byte, OR the masks together */
		*ob++ |= *p++ | *q++;
		*ob++ |= *p++ | *q++;
		*ob++ |= *p++ | *q++;
		*ob++ |= *p++ | *q++;
		*ob++ |= *p++ | *q++;
		*ob++ |= *p++ | *q++;
		*ob++ |= *p++ | *q++;
		*ob++ |= *p++ | *q++;
	}
}

/* The nonlinear function f(r,k), the heart of DES */
static uint32_t f(DES_KEY * key, register uint32_t r, register char *subkey)
{
	register uint32_t *spp;
	register uint32_t rval, rt;
	register int er;

#ifdef	TRACE
	printf("f(%08lx, %02x %02x %02x %02x %02x %02x %02x %02x) = ",
	       r,
	       subkey[0], subkey[1], subkey[2],
	       subkey[3], subkey[4], subkey[5], subkey[6], subkey[7]);
#endif
	/* Run E(R) ^ K through the combined S & P boxes.
	 * This code takes advantage of a convenient regularity in
	 * E, namely that each group of 6 bits in E(R) feeding
	 * a single S-box is a contiguous segment of R.
	 */
	subkey += 7;

	/* Compute E(R) for each block of 6 bits, and run thru boxes */
	er = ((int) r << 1) | ((r & 0x80000000) ? 1 : 0);
	spp = &key->sp[7][0];
	rval = spp[(er ^ *subkey--) & 0x3f];
	spp -= 64;
	rt = (uint32_t) r >> 3;
	rval |= spp[((int) rt ^ *subkey--) & 0x3f];
	spp -= 64;
	rt >>= 4;
	rval |= spp[((int) rt ^ *subkey--) & 0x3f];
	spp -= 64;
	rt >>= 4;
	rval |= spp[((int) rt ^ *subkey--) & 0x3f];
	spp -= 64;
	rt >>= 4;
	rval |= spp[((int) rt ^ *subkey--) & 0x3f];
	spp -= 64;
	rt >>= 4;
	rval |= spp[((int) rt ^ *subkey--) & 0x3f];
	spp -= 64;
	rt >>= 4;
	rval |= spp[((int) rt ^ *subkey--) & 0x3f];
	spp -= 64;
	rt >>= 4;
	rt |= (r & 1) << 5;
	rval |= spp[((int) rt ^ *subkey) & 0x3f];
#ifdef	TRACE
	printf(" %08lx\n", rval);
#endif
	return rval;
}

/* initialize a perm array */
static void perminit_ip(DES_KEY * key)
{
	register int l, j, k;
	int i, m;

	/* Clear the permutation array */
	Bzero(key->iperm, 16 * 16 * 8);

	for (i = 0; i < 16; i++)	/* each input nibble position */
		for (j = 0; j < 16; j++)	/* each possible input nibble */
			for (k = 0; k < 64; k++) {	/* each output bit position */
				l = ip[k] - 1;	/* where does this bit come from */
				if ((l >> 2) != i)	/* does it come from input posn? */
					continue;	/* if not, bit k is 0    */
				if (!(j & nibblebit[l & 3]))
					continue;	/* any such bit in input? */
				m = k & 07;	/* which bit is this in the byte */
				key->iperm[i][j][k >> 3] |= bytebit[m];
			}
}

static void perminit_fp(DES_KEY * key)
{
	register int l, j, k;
	int i, m;

	/* Clear the permutation array */
	Bzero(key->fperm, 16 * 16 * 8);

	for (i = 0; i < 16; i++)	/* each input nibble position */
		for (j = 0; j < 16; j++)	/* each possible input nibble */
			for (k = 0; k < 64; k++) {	/* each output bit position */
				l = fp[k] - 1;	/* where does this bit come from */
				if ((l >> 2) != i)	/* does it come from input posn? */
					continue;	/* if not, bit k is 0    */
				if (!(j & nibblebit[l & 3]))
					continue;	/* any such bit in input? */
				m = k & 07;	/* which bit is this in the byte */
				key->fperm[i][j][k >> 3] |= bytebit[m];
			}
}

/* Initialize the lookup table for the combined S and P boxes */
static void spinit(DES_KEY * key)
{
	char pbox[32];
	int p, i, s, j, rowcol;
	uint32_t val;

	/* Compute pbox, the inverse of p32i.
	 * This is easier to work with
	 */
	for (p = 0; p < 32; p++) {
		for (i = 0; i < 32; i++) {
			if (p32i[i] - 1 == p) {
				pbox[p] = i;
				break;
			}
		}
	}
	for (s = 0; s < 8; s++) {	/* For each S-box */
		for (i = 0; i < 64; i++) {	/* For each possible input */
			val = 0;
			/* The row number is formed from the first and last
			 * bits; the column number is from the middle 4
			 */
			rowcol =
			    (i & 32) | ((i & 1) ? 16 : 0) | ((i >> 1) &
							     0xf);
			for (j = 0; j < 4; j++) {	/* For each output bit */
				if (si[s][rowcol] & (8 >> j)) {
					val |=
					    1L << (31 - pbox[4 * s + j]);
				}
			}
			key->sp[s][i] = val;

#ifdef DEBUG
			printf("sp[%d][%2d] = %08lx\n", s, i,
			       key->sp[s][i]);
#endif
		}
	}
}