// ********** SPECIAL ************//
// p_first and p_second are already encrypted
// return homomorphic sum of the 2 plaintext
public override byte[] Addition(byte[] p_first, byte[] p_second)
{
//TODO: write addition
var blocksize = o_key_struct.getCiphertextBlocksize();
if (p_first.Length != blocksize)
{
throw new System.ArgumentException("p_first", "Ciphertext to multiply should be exactly one block long.");
}
if (p_second.Length != blocksize)
{
throw new System.ArgumentException("p_second", "Ciphertext to multiply should be exactly one block long.");
}
// convert byte array to BigInteger
BigInteger A = new BigInteger(p_first);
BigInteger B = new BigInteger(p_second);
BigInteger result = A * B % (o_key_struct.N * o_key_struct.N);
byte[] result_byte = result.getBytes();
return(result_byte);
//byte[] toBeDecrypted = new byte[blocksize];
//Array.Copy(result_byte, 0, toBeDecrypted, blocksize - result_byte.Length, result_byte.Length);
//return toBeDecrypted;
}
public PaillierAbstractCipher(PaillierKeyStruct p_key_struct)
{
// set the key details
o_key_struct = p_key_struct;
// calculate the blocksizes
o_plaintext_blocksize = p_key_struct.getPlaintextBlocksize();
o_ciphertext_blocksize = p_key_struct.getCiphertextBlocksize();
// set the default block for plaintext, which is suitable for encryption
o_block_size = o_plaintext_blocksize;
}
// ********** SPECIAL ************//
// p_first and p_second are already encrypted
// return homomorphic sum of the 2 plaintext
public override byte[] Addition(byte[] p_first, byte[] p_second)
{
var blocksize = o_key_struct.getCiphertextBlocksize();
if (p_first.Length != blocksize)
{
throw new ArgumentException("p_first", "Ciphertext to multiply should be exactly one block long.");
}
if (p_second.Length != blocksize)
{
throw new ArgumentException("p_second", "Ciphertext to multiply should be exactly one block long.");
}
return(Homomorphism.PaillierHomomorphism.Addition(p_first, p_second, o_key_struct.N.getBytes()));
}
