#include <string.h>
#include "XTEA.h"



void XTEA::setKey(void* key) {
	memcpy(_key, key, 16);
}


void XTEA::setIV(void* iv) {
	memcpy(_vector, iv, 8);
}


void XTEA::setIV(uint32_t ivh = 0, uint32_t ivl = 0) {
	memcpy(_vector, &ivh, 4);
	memcpy(_vector+4, &ivl, 4);
}


void XTEA::cbc_encrypt(void *dest, const void *plain, uint16_t nr_blocks) {
	for (uint32_t i = 0; i < nr_blocks; i++) {

		// XOR the current vector with the block before encrypting
		for (auto j = 0; j < 8; j++) {
			((uint8_t*)plain)[i*8 + j] ^= _vector[j];
		}

		// Encrypt the block
		encrypt_block((uint8_t*)dest + i*8, (uint8_t*)plain + i*8);

		// Copy the cipher output to the current vector
		memcpy(_vector, (uint8_t*)dest + i*8, 8);
	}
}


void XTEA::cbc_decrypt(void *dest, const void *cipher, uint16_t nr_blocks) {
	for (uint32_t i = 0; i < nr_blocks; i++) {

		// Decrypt the block
		decrypt_block((uint8_t*)dest + i*8, (uint8_t*)cipher + i*8);

		// XOR the output with the current vector to fully decrypt
		for (auto j = 0; j < 8; j++) {
			((uint8_t*)dest)[i*8 + j] ^= _vector[j];
		}

		// Copy the cipher text to the current vector
		memcpy(_vector, (uint8_t*)cipher + i*8, 8);
	}
}


void XTEA::encrypt_block(void *dest, const void *block) {
	uint8_t i;
	uint32_t v0=((uint32_t*)block)[0], v1=((uint32_t*)block)[1];
	uint32_t sum=0, delta=0x9E3779B9;
	for(i=0; i<XTEA_CYCLES; i++) {
		v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + ((uint32_t*)_key)[sum & 3]);
		sum += delta;
		v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + ((uint32_t*)_key)[sum>>11 & 3]);
	}
	((uint32_t*)dest)[0]=v0; ((uint32_t*)dest)[1]=v1;
}


void XTEA::decrypt_block(void *dest, const void *block) {
	uint8_t i;
	uint32_t v0=((uint32_t*)block)[0], v1=((uint32_t*)block)[1];
	uint32_t delta=0x9E3779B9, sum=delta*XTEA_CYCLES;
	for(i=0; i<XTEA_CYCLES; i++) {
		v1 -= ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + ((uint32_t*)_key)[sum>>11 & 3]);
		sum -= delta;
		v0 -= ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + ((uint32_t*)_key)[sum & 3]);
	}
	((uint32_t*)dest)[0]=v0; ((uint32_t*)dest)[1]=v1;
}