des.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

		l |= iptab[(block[i] >> 5) & 7] >> i;
		l |= iptab[(block[i] >> 1) & 7] << (16 - i);
	}
	return l;
}

/*
 *	Final Permutation
 */
static unsigned long	fptab[] = {
0x00000000,0x80000000,0x00800000,0x80800000,0x00008000,0x80008000,0x00808000,0x80808000,
0x00000080,0x80000080,0x00800080,0x80800080,0x00008080,0x80008080,0x00808080,0x80808080,
};

static void
fp(long left, long right, char text[8])
{
	unsigned long ta[2], t, v[2];
	int i, j, sh;

	ta[0] = right;
	ta[1] = left;
	v[0] = v[1] = 0;
	for(i = 0; i < 2; i++){
		t = ta[i];
		sh = i;
		for(j = 0; j < 4; j++){
			v[1] |= fptab[t & 0xf] >> sh;
			t >>= 4;
			v[0] |= fptab[t & 0xf] >> sh;
			t >>= 4;
			sh += 2;
		}
	}
	for(i = 0; i < 2; i++)
		for(j = 0; j < 4; j++){
			*text++ = v[i];
			v[i] >>= 8;
		}
}

/*
 *	Key set-up
 */
static uchar keyexpand[][15][2] = {
	{   3,  2,   9,  8,  18,  8,  27, 32,  33,  2,  42, 16,  48,  8,  65, 16, 
	   74,  2,  80,  2,  89,  4,  99, 16, 104,  4, 122, 32,   0,  0, },
	{   1,  4,   8,  1,  18,  4,  25, 32,  34, 32,  41,  8,  50,  8,  59, 32, 
	   64, 16,  75,  4,  90,  1,  97, 16, 106,  2, 112,  2, 123,  1, },
	{   2,  1,  19,  8,  35,  1,  40,  1,  50,  4,  57, 32,  75,  2,  80, 32, 
	   89,  1,  96, 16, 107,  4, 120,  8,   0,  0,   0,  0,   0,  0, },
	{   4, 32,  20,  2,  31,  4,  37, 32,  47,  1,  54,  1,  63,  2,  68,  1, 
	   78,  4,  84,  8, 101, 16, 108,  4, 119, 16, 126,  8,   0,  0, },
	{   5,  4,  15,  4,  21, 32,  31,  1,  38,  1,  47,  2,  53,  2,  68,  8, 
	   85, 16,  92,  4, 103, 16, 108, 32, 118, 32, 124,  2,   0,  0, },
	{  15,  2,  21,  2,  39,  8,  46, 16,  55, 32,  61,  1,  71, 16,  76, 32, 
	   86, 32,  93,  4, 102,  2, 108, 16, 117,  8, 126,  1,   0,  0, },
	{  14, 16,  23, 32,  29,  1,  38,  8,  52,  2,  63,  4,  70,  2,  76, 16, 
	   85,  8, 100,  1, 110,  4, 116,  8, 127,  8,   0,  0,   0,  0, },
	{   1,  8,   8, 32,  17,  1,  24, 16,  35,  4,  50,  1,  57, 16,  67,  8, 
	   83,  1,  88,  1,  98,  4, 105, 32, 114, 32, 123,  2,   0,  0, },
	{   0,  1,  11, 16,  16,  4,  35,  2,  40, 32,  49,  1,  56, 16,  65,  2, 
	   74, 16,  80,  8,  99,  8, 115,  1, 121,  4,   0,  0,   0,  0, },
	{   9, 16,  18,  2,  24,  2,  33,  4,  43, 16,  48,  4,  66, 32,  73,  8, 
	   82,  8,  91, 32,  97,  2, 106, 16, 112,  8, 122,  1,   0,  0, },
	{  14, 32,  21,  4,  30,  2,  36, 16,  45,  8,  60,  1,  69,  2,  87,  8, 
	   94, 16, 103, 32, 109,  1, 118,  8, 124, 32,   0,  0,   0,  0, },
	{   7,  4,  14,  2,  20, 16,  29,  8,  44,  1,  54,  4,  60,  8,  71,  8, 
	   78, 16,  87, 32,  93,  1, 102,  8, 116,  2, 125,  4,   0,  0, },
	{   7,  2,  12,  1,  22,  4,  28,  8,  45, 16,  52,  4,  63, 16,  70,  8, 
	   84,  2,  95,  4, 101, 32, 111,  1, 118,  1,   0,  0,   0,  0, },
	{   6, 16,  13, 16,  20,  4,  31, 16,  36, 32,  46, 32,  53,  4,  62,  2, 
	   69, 32,  79,  1,  86,  1,  95,  2, 101,  2, 119,  8,   0,  0, },
	{   0, 32,  10,  8,  19, 32,  25,  2,  34, 16,  40,  8,  59,  8,  66,  2, 
	   72,  2,  81,  4,  91, 16,  96,  4, 115,  2, 121,  8,   0,  0, },
	{   3, 16,  10,  4,  17, 32,  26, 32,  33,  8,  42,  8,  51, 32,  57,  2, 
	   67,  4,  82,  1,  89, 16,  98,  2, 104,  2, 113,  4, 120,  1, },
	{   1, 16,  11,  8,  27,  1,  32,  1,  42,  4,  49, 32,  58, 32,  67,  2, 
	   72, 32,  81,  1,  88, 16,  99,  4, 114,  1,   0,  0,   0,  0, },
	{   6, 32,  12,  2,  23,  4,  29, 32,  39,  1,  46,  1,  55,  2,  61,  2, 
	   70,  4,  76,  8,  93, 16, 100,  4, 111, 16, 116, 32,   0,  0, },
	{   6,  2,  13, 32,  23,  1,  30,  1,  39,  2,  45,  2,  63,  8,  77, 16, 
	   84,  4,  95, 16, 100, 32, 110, 32, 117,  4, 127,  4,   0,  0, },
	{   4,  1,  13,  2,  31,  8,  38, 16,  47, 32,  53,  1,  62,  8,  68, 32, 
	   78, 32,  85,  4,  94,  2, 100, 16, 109,  8, 127,  2,   0,  0, },
	{   5, 16,  15, 32,  21,  1,  30,  8,  44,  2,  55,  4,  61, 32,  68, 16, 
	   77,  8,  92,  1, 102,  4, 108,  8, 126, 16,   0,  0,   0,  0, },
	{   2,  8,   9,  1,  16, 16,  27,  4,  42,  1,  49, 16,  58,  2,  75,  1, 
	   80,  1,  90,  4,  97, 32, 106, 32, 113,  8, 120, 32,   0,  0, },
	{   2,  4,   8,  4,  27,  2,  32, 32,  41,  1,  48, 16,  59,  4,  66, 16, 
	   72,  8,  91,  8, 107,  1, 112,  1, 123, 16,   0,  0,   0,  0, },
	{   3,  8,  10,  2,  16,  2,  25,  4,  35, 16,  40,  4,  59,  2,  65,  8, 
	   74,  8,  83, 32,  89,  2,  98, 16, 104,  8, 121, 16,   0,  0, },
	{   4,  2,  13,  4,  22,  2,  28, 16,  37,  8,  52,  1,  62,  4,  79,  8, 
	   86, 16,  95, 32, 101,  1, 110,  8, 126, 32,   0,  0,   0,  0, },
	{   5, 32,  12, 16,  21,  8,  36,  1,  46,  4,  52,  8,  70, 16,  79, 32, 
	   85,  1,  94,  8, 108,  2, 119,  4, 126,  2,   0,  0,   0,  0, },
	{   5,  2,  14,  4,  20,  8,  37, 16,  44,  4,  55, 16,  60, 32,  76,  2, 
	   87,  4,  93, 32, 103,  1, 110,  1, 119,  2, 124,  1,   0,  0, },
	{   7, 32,  12,  4,  23, 16,  28, 32,  38, 32,  45,  4,  54,  2,  60, 16, 
	   71,  1,  78,  1,  87,  2,  93,  2, 111,  8, 118, 16, 125, 16, },
	{   1,  1,  11, 32,  17,  2,  26, 16,  32,  8,  51,  8,  64,  2,  73,  4, 
	   83, 16,  88,  4, 107,  2, 112, 32, 122,  8,   0,  0,   0,  0, },
	{   0,  4,   9, 32,  18, 32,  25,  8,  34,  8,  43, 32,  49,  2,  58, 16, 
	   74,  1,  81, 16,  90,  2,  96,  2, 105,  4, 115, 16, 122,  4, },
	{   2,  2,  19,  1,  24,  1,  34,  4,  41, 32,  50, 32,  57,  8,  64, 32, 
	   73,  1,  80, 16,  91,  4, 106,  1, 113, 16, 123,  8,   0,  0, },
	{   3,  4,  10, 16,  16,  8,  35,  8,  51,  1,  56,  1,  67, 16,  72,  4, 
	   91,  2,  96, 32, 105,  1, 112, 16, 121,  2,   0,  0,   0,  0, },
	{   4, 16,  15,  1,  22,  1,  31,  2,  37,  2,  55,  8,  62, 16,  69, 16, 
	   76,  4,  87, 16,  92, 32, 102, 32, 109,  4, 118,  2, 125, 32, },
	{   6,  4,  23,  8,  30, 16,  39, 32,  45,  1,  54,  8,  70, 32,  77,  4, 
	   86,  2,  92, 16, 101,  8, 116,  1, 125,  2,   0,  0,   0,  0, },
	{   4,  4,  13,  1,  22,  8,  36,  2,  47,  4,  53, 32,  63,  1,  69,  8, 
	   84,  1,  94,  4, 100,  8, 117, 16, 127, 32,   0,  0,   0,  0, },
	{   3, 32,   8, 16,  19,  4,  34,  1,  41, 16,  50,  2,  56,  2,  67,  1, 
	   72,  1,  82,  4,  89, 32,  98, 32, 105,  8, 114,  8, 121,  1, },
	{   1, 32,  19,  2,  24, 32,  33,  1,  40, 16,  51,  4,  64,  8,  83,  8, 
	   99,  1, 104,  1, 114,  4, 120,  4,   0,  0,   0,  0,   0,  0, },
	{   8,  2,  17,  4,  27, 16,  32,  4,  51,  2,  56, 32,  66,  8,  75, 32, 
	   81,  2,  90, 16,  96,  8, 115,  8, 122,  2,   0,  0,   0,  0, },
	{   2, 16,  18,  1,  25, 16,  34,  2,  40,  2,  49,  4,  59, 16,  66,  4, 
	   73, 32,  82, 32,  89,  8,  98,  8, 107, 32, 113,  2, 123,  4, },
	{   7,  1,  13,  8,  28,  1,  38,  4,  44,  8,  61, 16,  71, 32,  77,  1, 
	   86,  8, 100,  2, 111,  4, 117, 32, 124, 16,   0,  0,   0,  0, },
	{  12,  8,  29, 16,  36,  4,  47, 16,  52, 32,  62, 32,  68,  2,  79,  4, 
	   85, 32,  95,  1, 102,  1, 111,  2, 117,  2, 126,  4,   0,  0, },
	{   5,  1,  15, 16,  20, 32,  30, 32,  37,  4,  46,  2,  52, 16,  61,  8, 
	   70,  1,  79,  2,  85,  2, 103,  8, 110, 16, 119, 32, 124,  4, },
	{   0, 16,   9,  2,  18, 16,  24,  8,  43,  8,  59,  1,  65,  4,  75, 16, 
	   80,  4,  99,  2, 104, 32, 113,  1, 123, 32,   0,  0,   0,  0, },
	{  10, 32,  17,  8,  26,  8,  35, 32,  41,  2,  50, 16,  56,  8,  66,  1, 
	   73, 16,  82,  2,  88,  2,  97,  4, 107, 16, 112,  4, 121, 32, },
	{   0,  2,  11,  1,  16,  1,  26,  4,  33, 32,  42, 32,  49,  8,  58,  8, 
	   65,  1,  72, 16,  83,  4,  98,  1, 105, 16, 114,  2,   0,  0, },
	{   8,  8,  27,  8,  43,  1,  48,  1,  58,  4,  64,  4,  83,  2,  88, 32, 
	   97,  1, 104, 16, 115,  4, 122, 16,   0,  0,   0,  0,   0,  0, },
	{   5,  8,  14,  1,  23,  2,  29,  2,  47,  8,  54, 16,  63, 32,  68,  4, 
	   79, 16,  84, 32,  94, 32, 101,  4, 110,  2, 116, 16, 127,  1, },
	{   4,  8,  15,  8,  22, 16,  31, 32,  37,  1,  46,  8,  60,  2,  69,  4, 
	   78,  2,  84, 16,  93,  8, 108,  1, 118,  4,   0,  0,   0,  0, },
	{   7, 16,  14,  8,  28,  2,  39,  4,  45, 32,  55,  1,  62,  1,  76,  1, 
	   86,  4,  92,  8, 109, 16, 116,  4, 125,  1,   0,  0,   0,  0, },
	{   1,  2,  11,  4,  26,  1,  33, 16,  42,  2,  48,  2,  57,  4,  64,  1, 
	   74,  4,  81, 32,  90, 32,  97,  8, 106,  8, 115, 32, 120, 16, },
	{   2, 32,  11,  2,  16, 32,  25,  1,  32, 16,  43,  4,  58,  1,  75,  8, 
	   91,  1,  96,  1, 106,  4, 113, 32,   0,  0,   0,  0,   0,  0, },
	{   3,  1,   9,  4,  19, 16,  24,  4,  43,  2,  48, 32,  57,  1,  67, 32, 
	   73,  2,  82, 16,  88,  8, 107,  8, 120,  2,   0,  0,   0,  0, },
	{   0,  8,  10,  1,  17, 16,  26,  2,  32,  2,  41,  4,  51, 16,  56,  4, 
	   65, 32,  74, 32,  81,  8,  90,  8,  99, 32, 105,  2, 114, 16, },
	{   6,  1,  20,  1,  30,  4,  36,  8,  53, 16,  60,  4,  69,  1,  78,  8, 
	   92,  2, 103,  4, 109, 32, 119,  1, 125,  8,   0,  0,   0,  0, },
	{   7,  8,  21, 16,  28,  4,  39, 16,  44, 32,  54, 32,  61,  4,  71,  4, 
	   77, 32,  87,  1,  94,  1, 103,  2, 109,  2, 124,  8,   0,  0, },
	{   6,  8,  12, 32,  22, 32,  29,  4,  38,  2,  44, 16,  53,  8,  71,  2, 
	   77,  2,  95,  8, 102, 16, 111, 32, 117,  1, 127, 16,   0,  0, }
};

void
key_setup(char key[DESKEYLEN], char *ek)
{
	int i, j, k, mask;
	uchar (*x)[2];

	memset(ek, 0, 128);
	x = keyexpand[0];
	for(i = 0; i < 7; i++){
		k = key[i];
		for(mask = 0x80; mask; mask >>= 1){
			if(k & mask)
				for(j = 0; j < 15; j++)
					ek[x[j][0]] |= x[j][1];
			x += 15;
		}
	}
}