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/* Sofware DES functions 
 * written 12 Dec 1986 by Phil Karn, KA9Q; large sections adapted from 
 * the 1977 public-domain program by Jim Gillogly 
 */ 
#define NULL	0 
 
#if defined(_M_I86) || defined(WIN32) 
#define LITTLE_ENDIAN 
#include <stdlib.h>  
#endif 
 
#ifdef WIN32 
#define CONSTANT_DATA 
#else 
#define CONSTANT_DATA __based(__segname("_CODE")) 
#endif 
 
//#define register 
//#define int short 
//#define PERMUTATION 
 
/* Tables defined in the Data Encryption Standard documents */ 
 
#ifdef PERMUTATION 
/* initial permutation IP */ 
static char CONSTANT_DATA 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 CONSTANT_DATA 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 
}; 
#endif 
 
/* 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 CONSTANT_DATA 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 CONSTANT_DATA totrot[] = { 
	1,2,4,6,8,10,12,14,15,17,19,21,23,25,27,28 
}; 
 
/* permuted choice key (table) */ 
static char CONSTANT_DATA 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 CONSTANT_DATA 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 CONSTANT_DATA 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() */ 
static long (*sp_)[64]; 	/* Combined S and P boxes */ 
 
#ifdef PERMUTATION 
static char CONSTANT_DATA (*iperm)[16][8];	/* Initial and final permutations */ 
static char (*fperm)[16][8]; 
#else 
#define iperm 0 
#define fperm 0 
#endif 
 
/* 8 6-bit subkeys for each of 16 rounds, initialized by setkey() */ 
static unsigned char (*kn)[8]; 
 
/* bit 0 is left-most in byte */ 
static int CONSTANT_DATA bytebit[] = { 
	0200,0100,040,020,010,04,02,01 
}; 
 
static int CONSTANT_DATA nibblebit[] = { 
	 010,04,02,01 
}; 
static int desmode; 
 
#ifdef	LITTLE_ENDIAN  
 
/* Byte swap a long */ 
 
static 
unsigned long 
byteswap(unsigned long x) 
{ 
	register char *cp,tmp; 
 
	cp = (char *)&x; 
	tmp = cp[3]; 
	cp[3] = cp[0]; 
	cp[0] = tmp; 
 
	tmp = cp[2]; 
	cp[2] = cp[1]; 
	cp[1] = tmp; 
 
	return x; 
} 
#endif 
 
#ifdef PERMUTATION 
/* initialize a perm array */ 
static 
void perminit(perm,p) 
char perm[16][16][8];			/* 64-bit, either init or final */ 
char p[64]; 
{ 
	register int l, j, k; 
	int i,m; 
 
	/* Clear the permutation array */ 
	for (i=0; i<16; i++) 
		for (j=0; j<16; j++) 
			for (k=0; k<8; k++) 
				perm[i][j][k]=0; 
 
	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 = p[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*/ 
			perm[i][j][k>>3] |= bytebit[m]; 
		} 
} 
#endif 
 
/* Initialize the lookup table for the combined S and P boxes */ 
static void 
spinit() 
{ 
	char pbox[32]; 
	int p,i,s,j,rowcol; 
	long 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]); 
				} 
			} 
			sp_[s][i] = val; 
 
#ifdef	DEBUG 
                        printf("sp_[%d][%2d] = %08lx\n",s,i,sp_[s][i]); 
#endif 
		} 
	} 
} 
 
 
/* Allocate space and initialize DES lookup arrays 
 * mode == 0: standard Data Encryption Algorithm 
 * mode == 1: DEA without initial and final permutations for speed 
 * mode == 2: DEA without permutations and with 128-byte key (completely 
 *	      independent subkeys for each round) 
 */ 
int desinit(int mode) 
{ 
	if(sp_ != NULL){ 
		/* Already initialized */ 
		return 0; 
	} 
	desmode = mode; 
	 
	if((sp_ = (long (*)[64])malloc(sizeof(long) * 8 * 64)) == NULL){ 
		return -1; 
	} 
	spinit(); 
	kn = (unsigned char (*)[8])malloc(sizeof(char) * 8 * 16); 
	if(kn == NULL){ 
		free((char *)sp_); 
		return -1; 
	} 
	if(mode == 1 || mode == 2)	/* No permutations */ 
		return 0; 
 
#ifdef PERMUTATION 
	iperm = (char (*)[16][8])malloc(sizeof(char) * 16 * 16 * 8); 
	if(iperm == NULL){ 
		free((char *)sp_); 
		free((char *)kn); 
		return -1; 
	} 
	perminit(iperm,ip); 
 
	fperm = (char (*)[16][8])malloc(sizeof(char) * 16 * 16 * 8); 
	if(fperm == NULL){ 
		free((char *)sp_); 
		free((char *)kn); 
		free((char *)iperm); 
		return -1; 
	} 
	perminit(fperm,fp); 
#endif	 
	 
	return 0; 
} 
/* Free up storage used by DES */ 
void desdone(void) 
{ 
	if(sp_ == NULL) 
		return; /* Already done */ 
 
	free((char *)sp_); 
	free((char *)kn); 
#ifdef PERMUTATION	 
	if(iperm != NULL) 
		free((char *)iperm); 
	if(fperm != NULL) 
		free((char *)fperm); 
	iperm = NULL; 
	fperm = NULL; 
#endif		 
 
	sp_ = NULL; 
	kn = NULL; 
} 
/* Set key (initialize key schedule array) */ 
 
void setkey(char *key) 
{ 
	char pc1m[56];		/* place to modify pc1 into */ 
	char pcr[56];		/* place to rotate pc1 into */ 
	register int i,j,l; 
	int m; 
 
	/* In mode 2, the 128 bytes of subkey are set directly from the 
         * user's key, allowing him to use completely independent 
	 * subkeys for each round. Note that the user MUST specify a 
	 * full 128 bytes. 
	 * 
	 * I would like to think that this technique gives the NSA a real 
         * headache, but I'm not THAT naive. 
	 */ 
	if(desmode == 2){ 
		for(i=0;i<16;i++) 
			for(j=0;j<8;j++) 
				kn[i][j] = *key++; 
		return; 
	} 
	/* Clear key schedule */ 
	for (i=0; i<16; i++) 
		for (j=0; j<8; j++) 
			kn[i][j]=0; 
 
	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]=(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; 
				kn[i][j/6] |= bytebit[l] >> 2; 
			} 
		} 
	} 
} 
 
 
/* Permute inblock with perm */ 
static void 
permute(inblock,perm,outblock) 
char *inblock, *outblock;		/* result into outblock,64 bits */ 
char perm[16][16][8];			/* 2K bytes defining perm. */ 
{ 
	register int i,j; 
	register char *ib, *ob; 	/* ptr to input or output block */ 
	register char *p, *q; 
 
	if(perm == NULL){ 
		/* No permutation, just copy */ 
		for(i=8; i!=0; i--) 
			*outblock++ = *inblock++; 
		return; 
	} 
	/* Clear output block	 */ 
	for (i=8, ob = outblock; i != 0; i--) 
		*ob++ = 0; 
 
	ib = inblock; 
	for (j = 0; j < 16; j += 2, ib++) { /* for each input nibble */ 
		ob = outblock; 
		p = perm[j][(*ib >> 4) & 017]; 
		q = perm[j + 1][*ib & 017]; 
		for (i = 8; i != 0; i--){   /* and each output byte */ 
			*ob++ |= *p++ | *q++;	/* OR the masks together*/ 
		} 
	} 
} 
/* The nonlinear function f(r,k), the heart of DES */ 
static 
long 
f(r,subkey) 
unsigned long r;		/* 32 bits */ 
unsigned char subkey[8];	/* 48-bit key for this round */ 
{ 
	register unsigned long rval,rt; 
#ifdef	TRACE 
	unsigned char *cp; 
	int i; 
 
        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. 
	 */ 
	rt = (r >> 1) | ((r & 1) ? 0x80000000 : 0); 
	rval = 0; 
	rval |= sp_[0][((rt >> 26) ^ *subkey++) & 0x3f]; 
	rval |= sp_[1][((rt >> 22) ^ *subkey++) & 0x3f]; 
	rval |= sp_[2][((rt >> 18) ^ *subkey++) & 0x3f]; 
	rval |= sp_[3][((rt >> 14) ^ *subkey++) & 0x3f]; 
	rval |= sp_[4][((rt >> 10) ^ *subkey++) & 0x3f]; 
	rval |= sp_[5][((rt >> 6) ^ *subkey++) & 0x3f]; 
	rval |= sp_[6][((rt >> 2) ^ *subkey++) & 0x3f]; 
	rt = (r << 1) | ((r & 0x80000000) ? 1 : 0); 
	rval |= sp_[7][(rt ^ *subkey) & 0x3f]; 
#ifdef	TRACE 
        printf(" %08lx\n",rval); 
#endif 
	return rval; 
} 
 
/* Do one DES cipher round */ 
static void 
round(num,block) 
int num;				/* i.e. the num-th one	 */ 
unsigned long *block; 
{ 
	long f(); 
 
	/* 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. 
	 */ 
	if(num & 1){ 
		block[1] ^= f(block[0],kn[num]); 
	} else { 
		block[0] ^= f(block[1],kn[num]); 
	} 
}           
 
/* In-place encryption of 64-bit block */ 
 
void endes(char *block) 
{ 
	register int i; 
	unsigned long work[2];		/* Working data storage */ 
	long tmp; 
 
	permute(block,iperm,(char *)work);	/* Initial Permutation */ 
#ifdef LITTLE_ENDIAN 
	work[0] = byteswap(work[0]); 
	work[1] = byteswap(work[1]); 
#endif 
 
	/* Do the 16 rounds */ 
	for (i=0; i<16; i++) 
		round(i,work); 
 
	/* Left/right half swap */ 
	tmp = work[0]; 
	work[0] = work[1];	 
	work[1] = tmp; 
 
#ifdef LITTLE_ENDIAN 
	work[0] = byteswap(work[0]); 
	work[1] = byteswap(work[1]); 
#endif 
	permute((char *)work,fperm,block);	/* Inverse initial permutation */ 
} 
/* In-place decryption of 64-bit block */ 
void dedes(char *block) 
{ 
	register int i; 
	unsigned long work[2];	/* Working data storage */ 
	long tmp; 
 
	permute(block,iperm,(char *)work);	/* Initial permutation */ 
 
#ifdef LITTLE_ENDIAN 
	work[0] = byteswap(work[0]); 
	work[1] = byteswap(work[1]); 
#endif 
 
	/* Left/right half swap */ 
	tmp = work[0]; 
	work[0] = work[1];	 
	work[1] = tmp; 
 
	/* Do the 16 rounds in reverse order */ 
	for (i=15; i >= 0; i--) 
		round(i,work); 
 
#ifdef LITTLE_ENDIAN 
	work[0] = byteswap(work[0]); 
	work[1] = byteswap(work[1]); 
#endif 
 
	permute((char *)work,fperm,block);	/* Inverse initial permutation */ 
}