byte * AES128::decrypt(byte *message) {
int i;
memcpy((void*)state, (const void*)message, 16);
initKey();
/*Generate Round Keys*/
/*
for(i = 0; i < 10; i++) {
computeKey(rcon[i], i+1);
}
*/
inv_addRoundKey(10);
inv_shiftRows();
inv_subBytes();
for(i = 0; i < 9; i++)
{
inv_addRoundKey(9-i);
inv_mixColumns();
inv_shiftRows();
inv_subBytes();
}
inv_addRoundKey(0);
memcpy((void*)message,(const void*)state,16);
return message;
}
//Decrypts one 16-byte array of data
void AES::decryptBlock(int keySize, uint8_t* state, uint8_t* key) {
int rounds=6+keySize/32;
addRoundKey(state,key+rounds*16);
for(int i=rounds-1;i>=0;i--) {
inv_shiftRows(state);
inv_subBytes(state);
addRoundKey(state,key+16*i);
if(i!=0) //don't mix columns on last round
inv_mixColumns(state);
}
}
//!!!MAIN FUNKTION!!!//
void inv_aes128(uint8_t state[16])
{
//Damn English - German Mix...
//Firste define all Masks[1-10]
//then precalculate Sbox_masked and also the correct roundKeys
//Try generating random sequence for Subbytes:
uint8_t hiding_sequence[16];
gen_random_sequence(hiding_sequence);
init_masking();
// 1.: Maskiert State mit m1'-m4'
remask(state,Mask[6],Mask[7],Mask[8],Mask[9],0,0,0,0);
//2.: Rundenschlüssel 11 (beinhalltet schon m1'-m4' und m
// Maske m1'-m4' => m
addRoundKey_masked(state, 10);
//3.: Maskierte Subbyte Operation
// Maske M => m'
//inv_subBytes_masked(state); // m => m'
//inv_subBytes_masked_rand(state,hiding_sequence);
//4.: Shiftrows
// Maske m' => m' (bleibt natürlich gleich)
//inv_shiftRows(state); // m' bleibt m'
if(rand()%2 == 1){
inv_subBytes_masked_rand(state,hiding_sequence);
inv_shiftRows(state);
}
else{
inv_shiftRows(state);
inv_subBytes_masked_rand(state,hiding_sequence);
}
//Loop für Rundenschlüssel 10->2
for (uint8_t i = 9; i > 0; i--) {
//5. Maske m' => m1-m4
addRoundKey_masked(state, i);
//6. Maske m1-m4 -> m1'-m4'
inv_mixColumns(state);
//7. Maske m1'-m4' -> m
remask(state,Mask[6],Mask[7],Mask[8],Mask[9],Mask[4],Mask[4],Mask[4],Mask[4]);
/*with Shuffling:*/
//8. Maske m => m'
//inv_subBytes_masked(state);
//9. Maske m' bleibt m'
//inv_shiftRows(state);
//gen_random_sequence(hiding_sequence);
if(rand()%2 == 1){
inv_subBytes_masked_rand(state,hiding_sequence);
inv_shiftRows(state);
}
else{
inv_shiftRows(state);
inv_subBytes_masked_rand(state,hiding_sequence);
}
/**/
}
//10. Addiert Rundenschlüssel 1:
//Maske m' => 0
addRoundKey_masked(state, 0);
//Fertig:-)
}
