Question

AES has a larger block and key length compared to DES. If we ever had to do multiple encryptions with AES because we had computers fast enough to brute force a 128-bit key, would we need to move to Two-AES or Triple-AES?

Answer 1

Yes, we would need Triple-Advanced Encryption Standard (Triple-AES) improving the security of the existing AES encryption algorithm. This is because Triple-AES or 3AES does not use a 128-bit key, but uses a 256-bit key to encrypt. Vulnerability to security attack is too low and the security it provides is stronger than the existing AES encryption standards. It uses three keys for encryption. It uses multiple encryptions. All keys are randomly generated and are independent. Also, Triple-AES is around 20% faster and thus outperforms. With 256 bit keys, brute force attack would not be able to crack the system, until some powerful quantum computing is innovated. It would use three keys, all in one large block totaling up to 768-bit keys for AES, making it most secure. Triple the key material is used to a cipher with the key size doubled.

For example, a triple AES-128 using three separate keys, you would get 384 bits of key material to use to obtain a keyspace equivalent to AES-256.

Hence, Triple-AES would be the best option.