cast.c

This isakmpd, a BSD-licensed ISAKMP/Oakley (a.k.a. IKE) implementation.

	0xB6F2CF3B, 0x9F326442, 0xCB15A4CC, 0xB01A4504,
	0xF1E47D8D, 0x844A1BE5, 0xBAE7DFDC, 0x42CBDA70,
	0xCD7DAE0A, 0x57E85B7A, 0xD53F5AF6, 0x20CF4D8C,
	0xCEA4D428, 0x79D130A4, 0x3486EBFB, 0x33D3CDDC,
	0x77853B53, 0x37EFFCB5, 0xC5068778, 0xE580B3E6,
	0x4E68B8F4, 0xC5C8B37E, 0x0D809EA2, 0x398FEB7C,
	0x132A4F94, 0x43B7950E, 0x2FEE7D1C, 0x223613BD,
	0xDD06CAA2, 0x37DF932B, 0xC4248289, 0xACF3EBC3,
	0x5715F6B7, 0xEF3478DD, 0xF267616F, 0xC148CBE4,
	0x9052815E, 0x5E410FAB, 0xB48A2465, 0x2EDA7FA4,
	0xE87B40E4, 0xE98EA084, 0x5889E9E1, 0xEFD390FC,
	0xDD07D35B, 0xDB485694, 0x38D7E5B2, 0x57720101,
	0x730EDEBC, 0x5B643113, 0x94917E4F, 0x503C2FBA,
	0x646F1282, 0x7523D24A, 0xE0779695, 0xF9C17A8F,
	0x7A5B2121, 0xD187B896, 0x29263A4D, 0xBA510CDF,
	0x81F47C9F, 0xAD1163ED, 0xEA7B5965, 0x1A00726E,
	0x11403092, 0x00DA6D77, 0x4A0CDD61, 0xAD1F4603,
	0x605BDFB0, 0x9EEDC364, 0x22EBE6A8, 0xCEE7D28A,
	0xA0E736A0, 0x5564A6B9, 0x10853209, 0xC7EB8F37,
	0x2DE705CA, 0x8951570F, 0xDF09822B, 0xBD691A6C,
	0xAA12E4F2, 0x87451C0F, 0xE0F6A27A, 0x3ADA4819,
	0x4CF1764F, 0x0D771C2B, 0x67CDB156, 0x350D8384,
	0x5938FA0F, 0x42399EF3, 0x36997B07, 0x0E84093D,
	0x4AA93E61, 0x8360D87B, 0x1FA98B0C, 0x1149382C,
	0xE97625A5, 0x0614D1B7, 0x0E25244B, 0x0C768347,
	0x589E8D82, 0x0D2059D1, 0xA466BB1E, 0xF8DA0A82,
	0x04F19130, 0xBA6E4EC0, 0x99265164, 0x1EE7230D,
	0x50B2AD80, 0xEAEE6801, 0x8DB2A283, 0xEA8BF59E
};

/* Macros to access 8-bit bytes out of a 32-bit word */
#define U8a(x) ( (u_int8_t) (x>>24) )
#define U8b(x) ( (u_int8_t) ((x>>16)&255) )
#define U8c(x) ( (u_int8_t) ((x>>8)&255) )
#define U8d(x) ( (u_int8_t) ((x)&255) )

/* Circular left shift */
#define ROL(x, n) ( ((x)<<(n)) | ((x)>>(32-(n))) )

/* CAST-128 uses three different round functions */
#define F1(l, r, i) \
	t = ROL(key->xkey[i] + r, key->xkey[i+16]); \
	l ^= ((cast_sbox1[U8a(t)] ^ cast_sbox2[U8b(t)]) - \
	 cast_sbox3[U8c(t)]) + cast_sbox4[U8d(t)];
#define F2(l, r, i) \
	t = ROL(key->xkey[i] ^ r, key->xkey[i+16]); \
	l ^= ((cast_sbox1[U8a(t)] - cast_sbox2[U8b(t)]) + \
	 cast_sbox3[U8c(t)]) ^ cast_sbox4[U8d(t)];
#define F3(l, r, i) \
	t = ROL(key->xkey[i] - r, key->xkey[i+16]); \
	l ^= ((cast_sbox1[U8a(t)] + cast_sbox2[U8b(t)]) ^ \
	 cast_sbox3[U8c(t)]) - cast_sbox4[U8d(t)];


/***** Encryption Function *****/

void cast_encrypt(cast_key* key, u_int8_t* inblock, u_int8_t* outblock)
{
u_int32_t t, l, r;

	/* Get inblock into l,r */
	l = ((u_int32_t)inblock[0] << 24) | ((u_int32_t)inblock[1] << 16) |
	 ((u_int32_t)inblock[2] << 8) | (u_int32_t)inblock[3];
	r = ((u_int32_t)inblock[4] << 24) | ((u_int32_t)inblock[5] << 16) |
	 ((u_int32_t)inblock[6] << 8) | (u_int32_t)inblock[7];
	/* Do the work */
	F1(l, r,  0);
	F2(r, l,  1);
	F3(l, r,  2);
	F1(r, l,  3);
	F2(l, r,  4);
	F3(r, l,  5);
	F1(l, r,  6);
	F2(r, l,  7);
	F3(l, r,  8);
	F1(r, l,  9);
	F2(l, r, 10);
	F3(r, l, 11);
	/* Only do full 16 rounds if key length > 80 bits */
	if (key->rounds > 12) {
		F1(l, r, 12);
		F2(r, l, 13);
		F3(l, r, 14);
		F1(r, l, 15);
	}
	/* Put l,r into outblock */
	outblock[0] = U8a(r);
	outblock[1] = U8b(r);
	outblock[2] = U8c(r);
	outblock[3] = U8d(r);
	outblock[4] = U8a(l);
	outblock[5] = U8b(l);
	outblock[6] = U8c(l);
	outblock[7] = U8d(l);
	/* Wipe clean */
	t = l = r = 0;
}


/***** Decryption Function *****/

void cast_decrypt(cast_key* key, u_int8_t* inblock, u_int8_t* outblock)
{
u_int32_t t, l, r;

	/* Get inblock into l,r */
	r = ((u_int32_t)inblock[0] << 24) | ((u_int32_t)inblock[1] << 16) |
	 ((u_int32_t)inblock[2] << 8) | (u_int32_t)inblock[3];
	l = ((u_int32_t)inblock[4] << 24) | ((u_int32_t)inblock[5] << 16) |
	 ((u_int32_t)inblock[6] << 8) | (u_int32_t)inblock[7];
	/* Do the work */
	/* Only do full 16 rounds if key length > 80 bits */
	if (key->rounds > 12) {
		F1(r, l, 15);
		F3(l, r, 14);
		F2(r, l, 13);
		F1(l, r, 12);
	}
	F3(r, l, 11);
	F2(l, r, 10);
	F1(r, l,  9);
	F3(l, r,  8);
	F2(r, l,  7);
	F1(l, r,  6);
	F3(r, l,  5);
	F2(l, r,  4);
	F1(r, l,  3);
	F3(l, r,  2);
	F2(r, l,  1);
	F1(l, r,  0);
	/* Put l,r into outblock */
	outblock[0] = U8a(l);
	outblock[1] = U8b(l);
	outblock[2] = U8c(l);
	outblock[3] = U8d(l);
	outblock[4] = U8a(r);
	outblock[5] = U8b(r);
	outblock[6] = U8c(r);
	outblock[7] = U8d(r);
	/* Wipe clean */
	t = l = r = 0;
}


/***** Key Schedual *****/

void cast_setkey(cast_key* key, u_int8_t* rawkey, int keybytes)
{
u_int32_t t[4], z[4], x[4];
int i;

	/* Set number of rounds to 12 or 16, depending on key length */
	key->rounds = (keybytes <= 10 ? 12 : 16);

	/* Copy key to workspace x */
	for (i = 0; i < 4; i++) {
		x[i] = 0;
		if ((i*4+0) < keybytes) x[i] = (u_int32_t)rawkey[i*4+0] << 24;
		if ((i*4+1) < keybytes) x[i] |= (u_int32_t)rawkey[i*4+1] << 16;
		if ((i*4+2) < keybytes) x[i] |= (u_int32_t)rawkey[i*4+2] << 8;
		if ((i*4+3) < keybytes) x[i] |= (u_int32_t)rawkey[i*4+3];
	}
	/* Generate 32 subkeys, four at a time */
	for (i = 0; i < 32; i+=4) {
		switch (i & 4) {
		 case 0:
			t[0] = z[0] = x[0] ^ cast_sbox5[U8b(x[3])] ^
			 cast_sbox6[U8d(x[3])] ^ cast_sbox7[U8a(x[3])] ^
			 cast_sbox8[U8c(x[3])] ^ cast_sbox7[U8a(x[2])];
			t[1] = z[1] = x[2] ^ cast_sbox5[U8a(z[0])] ^
			 cast_sbox6[U8c(z[0])] ^ cast_sbox7[U8b(z[0])] ^
			 cast_sbox8[U8d(z[0])] ^ cast_sbox8[U8c(x[2])];
			t[2] = z[2] = x[3] ^ cast_sbox5[U8d(z[1])] ^
			 cast_sbox6[U8c(z[1])] ^ cast_sbox7[U8b(z[1])] ^
			 cast_sbox8[U8a(z[1])] ^ cast_sbox5[U8b(x[2])];
			t[3] = z[3] = x[1] ^ cast_sbox5[U8c(z[2])] ^
			 cast_sbox6[U8b(z[2])] ^ cast_sbox7[U8d(z[2])] ^
			 cast_sbox8[U8a(z[2])] ^ cast_sbox6[U8d(x[2])];
			break;
		 case 4:
			t[0] = x[0] = z[2] ^ cast_sbox5[U8b(z[1])] ^
			 cast_sbox6[U8d(z[1])] ^ cast_sbox7[U8a(z[1])] ^
			 cast_sbox8[U8c(z[1])] ^ cast_sbox7[U8a(z[0])];
			t[1] = x[1] = z[0] ^ cast_sbox5[U8a(x[0])] ^
			 cast_sbox6[U8c(x[0])] ^ cast_sbox7[U8b(x[0])] ^
			 cast_sbox8[U8d(x[0])] ^ cast_sbox8[U8c(z[0])];
			t[2] = x[2] = z[1] ^ cast_sbox5[U8d(x[1])] ^
			 cast_sbox6[U8c(x[1])] ^ cast_sbox7[U8b(x[1])] ^
			 cast_sbox8[U8a(x[1])] ^ cast_sbox5[U8b(z[0])];
			t[3] = x[3] = z[3] ^ cast_sbox5[U8c(x[2])] ^
			 cast_sbox6[U8b(x[2])] ^ cast_sbox7[U8d(x[2])] ^
			 cast_sbox8[U8a(x[2])] ^ cast_sbox6[U8d(z[0])];
			break;
		}
		switch (i & 12) {
		 case 0:
		 case 12:
			key->xkey[i+0] = cast_sbox5[U8a(t[2])] ^ cast_sbox6[U8b(t[2])] ^
			 cast_sbox7[U8d(t[1])] ^ cast_sbox8[U8c(t[1])];
			key->xkey[i+1] = cast_sbox5[U8c(t[2])] ^ cast_sbox6[U8d(t[2])] ^
			 cast_sbox7[U8b(t[1])] ^ cast_sbox8[U8a(t[1])];
			key->xkey[i+2] = cast_sbox5[U8a(t[3])] ^ cast_sbox6[U8b(t[3])] ^
			 cast_sbox7[U8d(t[0])] ^ cast_sbox8[U8c(t[0])];
			key->xkey[i+3] = cast_sbox5[U8c(t[3])] ^ cast_sbox6[U8d(t[3])] ^
			 cast_sbox7[U8b(t[0])] ^ cast_sbox8[U8a(t[0])];
			break;
		 case 4:
		 case 8:
			key->xkey[i+0] = cast_sbox5[U8d(t[0])] ^ cast_sbox6[U8c(t[0])] ^
			 cast_sbox7[U8a(t[3])] ^ cast_sbox8[U8b(t[3])];
			key->xkey[i+1] = cast_sbox5[U8b(t[0])] ^ cast_sbox6[U8a(t[0])] ^
			 cast_sbox7[U8c(t[3])] ^ cast_sbox8[U8d(t[3])];
			key->xkey[i+2] = cast_sbox5[U8d(t[1])] ^ cast_sbox6[U8c(t[1])] ^
			 cast_sbox7[U8a(t[2])] ^ cast_sbox8[U8b(t[2])];
			key->xkey[i+3] = cast_sbox5[U8b(t[1])] ^ cast_sbox6[U8a(t[1])] ^
			 cast_sbox7[U8c(t[2])] ^ cast_sbox8[U8d(t[2])];
			break;
		}
		switch (i & 12) {
		 case 0:
			key->xkey[i+0] ^= cast_sbox5[U8c(z[0])];
			key->xkey[i+1] ^= cast_sbox6[U8c(z[1])];
			key->xkey[i+2] ^= cast_sbox7[U8b(z[2])];
			key->xkey[i+3] ^= cast_sbox8[U8a(z[3])];
			break;
		 case 4:
			key->xkey[i+0] ^= cast_sbox5[U8a(x[2])];
			key->xkey[i+1] ^= cast_sbox6[U8b(x[3])];
			key->xkey[i+2] ^= cast_sbox7[U8d(x[0])];
			key->xkey[i+3] ^= cast_sbox8[U8d(x[1])];
			break;
		 case 8:
			key->xkey[i+0] ^= cast_sbox5[U8b(z[2])];
			key->xkey[i+1] ^= cast_sbox6[U8a(z[3])];
			key->xkey[i+2] ^= cast_sbox7[U8c(z[0])];
			key->xkey[i+3] ^= cast_sbox8[U8c(z[1])];
			break;
		 case 12:
			key->xkey[i+0] ^= cast_sbox5[U8d(x[0])];
			key->xkey[i+1] ^= cast_sbox6[U8d(x[1])];
			key->xkey[i+2] ^= cast_sbox7[U8a(x[2])];
			key->xkey[i+3] ^= cast_sbox8[U8b(x[3])];
			break;
		}
		if (i >= 16) {
			key->xkey[i+0] &= 31;
			key->xkey[i+1] &= 31;
			key->xkey[i+2] &= 31;
			key->xkey[i+3] &= 31;
		}
	}
	/* Wipe clean */
	for (i = 0; i < 4; i++) {
		t[i] = x[i] = z[i] = 0;
	}
}

/* Made in Canada */