83 lines
2.0 KiB
C++
83 lines
2.0 KiB
C++
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#include <string.h>
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#include "XTEA.h"
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void XTEA::setKey(void* key) {
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memcpy(_key, key, 16);
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}
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void XTEA::setIV(void* iv) {
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memcpy(_vector, iv, 8);
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}
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void XTEA::setIV(uint32_t ivh = 0, uint32_t ivl = 0) {
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memcpy(_vector, &ivh, 4);
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memcpy(_vector+4, &ivl, 4);
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}
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void XTEA::cbc_encrypt(void *dest, const void *plain, uint16_t nr_blocks) {
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for (uint32_t i = 0; i < nr_blocks; i++) {
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// XOR the current vector with the block before encrypting
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for (auto j = 0; j < 8; j++) {
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((uint8_t*)plain)[i*8 + j] ^= _vector[j];
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}
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// Encrypt the block
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encrypt_block((uint8_t*)dest + i*8, (uint8_t*)plain + i*8);
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// Copy the cipher output to the current vector
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memcpy(_vector, (uint8_t*)dest + i*8, 8);
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}
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}
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void XTEA::cbc_decrypt(void *dest, const void *cipher, uint16_t nr_blocks) {
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for (uint32_t i = 0; i < nr_blocks; i++) {
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// Decrypt the block
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decrypt_block((uint8_t*)dest + i*8, (uint8_t*)cipher + i*8);
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// XOR the output with the current vector to fully decrypt
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for (auto j = 0; j < 8; j++) {
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((uint8_t*)dest)[i*8 + j] ^= _vector[j];
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}
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// Copy the cipher text to the current vector
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memcpy(_vector, (uint8_t*)cipher + i*8, 8);
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}
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}
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void XTEA::encrypt_block(void *dest, const void *block) {
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uint8_t i;
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uint32_t v0=((uint32_t*)block)[0], v1=((uint32_t*)block)[1];
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uint32_t sum=0, delta=0x9E3779B9;
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for(i=0; i<XTEA_CYCLES; i++) {
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v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + ((uint32_t*)_key)[sum & 3]);
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sum += delta;
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v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + ((uint32_t*)_key)[sum>>11 & 3]);
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}
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((uint32_t*)dest)[0]=v0; ((uint32_t*)dest)[1]=v1;
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}
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void XTEA::decrypt_block(void *dest, const void *block) {
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uint8_t i;
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uint32_t v0=((uint32_t*)block)[0], v1=((uint32_t*)block)[1];
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uint32_t delta=0x9E3779B9, sum=delta*XTEA_CYCLES;
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for(i=0; i<XTEA_CYCLES; i++) {
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v1 -= ((v0 << 4 ^ v0 >> 5) + v0) ^ (sum + ((uint32_t*)_key)[sum>>11 & 3]);
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sum -= delta;
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v0 -= ((v1 << 4 ^ v1 >> 5) + v1) ^ (sum + ((uint32_t*)_key)[sum & 3]);
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}
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((uint32_t*)dest)[0]=v0; ((uint32_t*)dest)[1]=v1;
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}
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