#include <rz_lib.h>
#include <rz_crypto.h>

#define BITS         1024
#define RC2_KEY_SIZE 64 // bytes
#define BLOCK_SIZE   8 // bytes

static const ut8 PITABLE[256] = {
	0xD9,
	0x78,
	0xF9,
	0xC4,
	0x19,
	0xDD,
	0xB5,
	0xED,
	0x28,
	0xE9,
	0xFD,
	0x79,
	0x4A,
	0xA0,
	0xD8,
	0x9D,
	0xC6,
	0x7E,
	0x37,
	0x83,
	0x2B,
	0x76,
	0x53,
	0x8E,
	0x62,
	0x4C,
	0x64,
	0x88,
	0x44,
	0x8B,
	0xFB,
	0xA2,
	0x17,
	0x9A,
	0x59,
	0xF5,
	0x87,
	0xB3,
	0x4F,
	0x13,
	0x61,
	0x45,
	0x6D,
	0x8D,
	0x09,
	0x81,
	0x7D,
	0x32,
	0xBD,
	0x8F,
	0x40,
	0xEB,
	0x86,
	0xB7,
	0x7B,
	0x0B,
	0xF0,
	0x95,
	0x21,
	0x22,
	0x5C,
	0x6B,
	0x4E,
	0x82,
	0x54,
	0xD6,
	0x65,
	0x93,
	0xCE,
	0x60,
	0xB2,
	0x1C,
	0x73,
	0x56,
	0xC0,
	0x14,
	0xA7,
	0x8C,
	0xF1,
	0xDC,
	0x12,
	0x75,
	0xCA,
	0x1F,
	0x3B,
	0xBE,
	0xE4,
	0xD1,
	0x42,
	0x3D,
	0xD4,
	0x30,
	0xA3,
	0x3C,
	0xB6,
	0x26,
	0x6F,
	0xBF,
	0x0E,
	0xDA,
	0x46,
	0x69,
	0x07,
	0x57,
	0x27,
	0xF2,
	0x1D,
	0x9B,
	0xBC,
	0x94,
	0x43,
	0x03,
	0xF8,
	0x11,
	0xC7,
	0xF6,
	0x90,
	0xEF,
	0x3E,
	0xE7,
	0x06,
	0xC3,
	0xD5,
	0x2F,
	0xC8,
	0x66,
	0x1E,
	0xD7,
	0x08,
	0xE8,
	0xEA,
	0xDE,
	0x80,
	0x52,
	0xEE,
	0xF7,
	0x84,
	0xAA,
	0x72,
	0xAC,
	0x35,
	0x4D,
	0x6A,
	0x2A,
	0x96,
	0x1A,
	0xD2,
	0x71,
	0x5A,
	0x15,
	0x49,
	0x74,
	0x4B,
	0x9F,
	0xD0,
	0x5E,
	0x04,
	0x18,
	0xA4,
	0xEC,
	0xC2,
	0xE0,
	0x41,
	0x6E,
	0x0F,
	0x51,
	0xCB,
	0xCC,
	0x24,
	0x91,
	0xAF,
	0x50,
	0xA1,
	0xF4,
	0x70,
	0x39,
	0x99,
	0x7C,
	0x3A,
	0x85,
	0x23,
	0xB8,
	0xB4,
	0x7A,
	0xFC,
	0x02,
	0x36,
	0x5B,
	0x25,
	0x55,
	0x97,
	0x31,
	0x2D,
	0x5D,
	0xFA,
	0x98,
	0xE3,
	0x8A,
	0x92,
	0xAE,
	0x05,
	0xDF,
	0x29,
	0x10,
	0x67,
	0x6C,
	0xBA,
	0xC9,
	0xD3,
	0x00,
	0xE6,
	0xCF,
	0xE1,
	0x9E,
	0xA8,
	0x2C,
	0x63,
	0x16,
	0x01,
	0x3F,
	0x58,
	0xE2,
	0x89,
	0xA9,
	0x0D,
	0x38,
	0x34,
	0x1B,
	0xAB,
	0x33,
	0xFF,
	0xB0,
	0xBB,
	0x48,
	0x0C,
	0x5F,
	0xB9,
	0xB1,
	0xCD,
	0x2E,
	0xC5,
	0xF3,
	0xDB,
	0x47,
	0xE5,
	0xA5,
	0x9C,
	0x77,
	0x0A,
	0xA6,
	0x20,
	0x68,
	0xFE,
	0x7F,
	0xC1,
	0xAD,
};

struct rc2_state {
	ut16 ekey[RC2_KEY_SIZE];
	int key_size;
};

// takes a 8-128 len ut8 key
// expands it to a 64 len ut16 key
static bool rc2_expandKey(struct rc2_state *state, const ut8 *key, int key_len) {
	int i;

	if (key_len < 1 || key_len > 128) {
		return false;
	}
	memcpy(state->ekey, key, key_len);

	// first loop
	for (i = key_len; i < 128; i++) {
		((ut8 *)state->ekey)[i] = PITABLE[(((ut8 *)state->ekey)[i - key_len] + ((ut8 *)state->ekey)[i - 1]) & 255];
	}

	int ekey_len = (BITS + 7) >> 3;
	i = 128 - ekey_len;
	((ut8 *)state->ekey)[i] = PITABLE[((ut8 *)state->ekey)[i] & (255 >> (7 & -BITS))];

	// second loop
	while (i--) {
		((ut8 *)state->ekey)[i] = PITABLE[((ut8 *)state->ekey)[i + 1] ^ ((ut8 *)state->ekey)[i + ekey_len]];
	}

	// generate the ut16 key
	for (i = RC2_KEY_SIZE - 1; i >= 0; i--) {
		state->ekey[i] = ((ut8 *)state->ekey)[i * 2] + (((ut8 *)state->ekey)[i * 2 + 1] << 8);
	}

	return true;
}

static void rc2_crypt8(struct rc2_state *state, const ut8 *inbuf, ut8 *outbuf) {
	int i;
	ut16 x76, x54, x32, x10;

	x76 = (inbuf[7] << 8) | inbuf[6];
	x54 = (inbuf[5] << 8) | inbuf[4];
	x32 = (inbuf[3] << 8) | inbuf[2];
	x10 = (inbuf[1] << 8) | inbuf[0];

	for (i = 0; i < 16; i++) {
		x10 += ((x32 & ~x76) + (x54 & x76)) + state->ekey[4 * i + 0];
		x10 = (x10 << 1) + (x10 >> 15 & 1);

		x32 += ((x54 & ~x10) + (x76 & x10)) + state->ekey[4 * i + 1];
		x32 = (x32 << 2) + (x32 >> 14 & 3);

		x54 += ((x76 & ~x32) + (x10 & x32)) + state->ekey[4 * i + 2];
		x54 = (x54 << 3) + (x54 >> 13 & 7);

		x76 += ((x10 & ~x54) + (x32 & x54)) + state->ekey[4 * i + 3];
		x76 = (x76 << 5) + (x76 >> 11 & 31);

		if (i == 4 || i == 10) {
			x10 += state->ekey[x76 & 63];
			x32 += state->ekey[x10 & 63];
			x54 += state->ekey[x32 & 63];
			x76 += state->ekey[x54 & 63];
		}
	}

	outbuf[0] = (ut8)x10;
	outbuf[1] = (ut8)(x10 >> 8);
	outbuf[2] = (ut8)x32;
	outbuf[3] = (ut8)(x32 >> 8);
	outbuf[4] = (ut8)x54;
	outbuf[5] = (ut8)(x54 >> 8);
	outbuf[6] = (ut8)x76;
	outbuf[7] = (ut8)(x76 >> 8);
}

static void rc2_dcrypt8(struct rc2_state *state, const ut8 *inbuf, ut8 *outbuf) {
	int i;
	ut16 x76, x54, x32, x10;

	x76 = (inbuf[7] << 8) | inbuf[6];
	x54 = (inbuf[5] << 8) | inbuf[4];
	x32 = (inbuf[3] << 8) | inbuf[2];
	x10 = (inbuf[1] << 8) | inbuf[0];

	for (i = 15; i >= 0; i--) {
		x76 &= 65535;
		x76 = (x76 << 11) | (x76 >> 5);
		x76 -= ((x10 & ~x54) | (x32 & x54)) + state->ekey[4 * i + 3];

		x76 &= 65535;
		x54 = (x54 << 13) | (x54 >> 3);
		x54 -= ((x76 & ~x32) | (x10 & x32)) + state->ekey[4 * i + 2];

		x32 &= 65535;
		x32 = (x32 << 14) | (x32 >> 2);
		x32 -= ((x54 & ~x10) | (x76 & x10)) + state->ekey[4 * i + 1];

		x10 &= 65535;
		x10 = (x10 << 15) | (x10 >> 1);
		x10 -= ((x32 & ~x76) | (x54 & x76)) + state->ekey[4 * i + 0];

		if (i == 5 || i == 11) {
			x76 -= state->ekey[x54 & 63];
			x54 -= state->ekey[x32 & 63];
			x32 -= state->ekey[x10 & 63];
			x10 -= state->ekey[x76 & 63];
		}
	}

	outbuf[0] = (ut8)x10;
	outbuf[1] = (ut8)(x10 >> 8);
	outbuf[2] = (ut8)x32;
	outbuf[3] = (ut8)(x32 >> 8);
	outbuf[4] = (ut8)x54;
	outbuf[5] = (ut8)(x54 >> 8);
	outbuf[6] = (ut8)x76;
	outbuf[7] = (ut8)(x76 >> 8);
}

static void rc2_dcrypt(struct rc2_state *state, const ut8 *inbuf, ut8 *outbuf, int buflen) {
	int i;
	char data_block[BLOCK_SIZE + 1] = { 0 };
	int idx = 0;
	char dcrypted_block[BLOCK_SIZE + 1] = { 0 };
	char *ptr = (char *)outbuf;

	for (i = 0; i < buflen; i++) {
		data_block[idx] = inbuf[i];
		idx += 1;
		if (idx % BLOCK_SIZE == 0) {
			rc2_dcrypt8(state, (const ut8 *)data_block, (ut8 *)dcrypted_block);
			memcpy(ptr, dcrypted_block, BLOCK_SIZE);
			ptr += BLOCK_SIZE;
			idx = 0;
		}
	}
}

static void rc2_crypt(struct rc2_state *state, const ut8 *inbuf, ut8 *outbuf, int buflen) {
	int i;
	char data_block[BLOCK_SIZE] = { 0 };
	int idx = 0;

	char crypted_block[BLOCK_SIZE] = { 0 };
	char *ptr = (char *)outbuf;

	// divide it into blocks of BLOCK_SIZE
	for (i = 0; i < buflen; i++) {
		data_block[idx] = inbuf[i];
		idx += 1;
		if (idx % BLOCK_SIZE == 0) {
			rc2_crypt8(state, (const ut8 *)data_block, (ut8 *)crypted_block);
			strncpy(ptr, crypted_block, BLOCK_SIZE);
			ptr += BLOCK_SIZE;
			idx = 0;
		}
	}

	if (idx % 8) {
		while (idx % 8) {
			data_block[idx++] = 0;
		}
		rc2_crypt8(state, (const ut8 *)data_block, (ut8 *)crypted_block);
		strncpy(ptr, crypted_block, 8);
	}
}

///////////////////////////////////////////////////////////

static struct rc2_state state;
static int flag = 0;

static bool rc2_set_key(RzCrypto *cry, const ut8 *key, int keylen, int mode, int direction) {
	flag = direction;
	state.key_size = 1024;
	return rc2_expandKey(&state, key, keylen);
}

static int rc2_get_key_size(RzCrypto *cry) {
	return state.key_size;
}

static bool rc2_use(const char *algo) {
	return !strcmp(algo, "rc2");
}

static bool update(RzCrypto *cry, const ut8 *buf, int len) {
	ut8 *obuf = calloc(1, len);
	if (!obuf) {
		return false;
	}
	if (flag == 0) {
		rc2_crypt(&state, buf, obuf, len);
	} else if (flag == 1) {
		rc2_dcrypt(&state, buf, obuf, len);
	}
	rz_crypto_append(cry, obuf, len);
	free(obuf);
	return true;
}

static bool final(RzCrypto *cry, const ut8 *buf, int len) {
	return update(cry, buf, len);
}

RzCryptoPlugin rz_crypto_plugin_rc2 = {
	.name = "rc2",
	.set_key = rc2_set_key,
	.get_key_size = rc2_get_key_size,
	.use = rc2_use,
	.update = update,
	.final = final
};

#ifndef RZ_PLUGIN_INCORE
RZ_API RzLibStruct rizin_plugin = {
	.type = RZ_LIB_TYPE_CRYPTO,
	.data = &rz_crypto_plugin_rc2,
	.version = RZ_VERSION
};
#endif

#if HAVE_MAIN
int main() {
	ut8 out[16];
	struct rc2_state st;
	st.key_size = 3;
	/* encrypt */
	rc2_expandKey((const ut8 *)"key", 3, BITS, &st);
	rc2_crypt(&st, (const ut8 *)"12345678abc", out, 11);
	eprintf("%s\n", (const char *)out);
	rc2_dcrypt(&st, (const ut8 *)out, out, sizeof(out));
	eprintf("%s\n", (const char *)out);
	return 0;
}
#endif
