SYMMETRIC ENCRYPTION
The initial encryption standard developed by NIST was called data encryption standard (DES). DES is too weak for modern applications since the key size is only 56-bit. It was replaced by advanced encryption standard (AES). AES has variable key sizes and can require a key size of 256-bit.
1. Discuss if you think AES key size has a direct relationship with algorithm strength.
2. Do you think that AES-256 is necessarily better than AES-128?
3. How long do you think it would take to launch a brute force attack on AES-128 using a standard computer?
SYMMETRIC ENCRYPTION
Advanced Encryption Standard (AES) uses the same key used to encrypt data to decrypt the same data, which is means it is a symmetric key encryption cipher. I think AES key size affects directly the algorithm and encryption strength. The more difficult it is to decipher a key, the more the strength of encryption. The difficulty of the discovery of the key depends on the type and quality of the cipher used and the length of the key.
The 256-bit encryption key is stronger and better than the 128-bit encryption key. The 256-bit encryption offers a higher level of protection than the 128-bit encryption. The 256-bit encryption has been made with stronger encryption to make data more secure. The 256-bit has more keys which increase the security of the encryption, the 256-bits keys enhance the number of AES that should be cracked for each data block to be by-passed. The 128-bit takes 10 rounds of cracking while the 256-bit encryption requires 14 rounds of cracking to by-pass. The 256-bit encryption adds a layer for more security. The layers consist of a username and password integrated with the 256-bit encryption. Generally, 256-bit encryption is stronger and better as it requires more crack time has better and integrates another layer of security.
Brute force attacks involve the attempt to make a combination of numbers possible to find the correct key combination through the exhaustive key search. It is harder to crack by brute force when the algorithm is complex. The practical feasibility of successfully performing a brute force attack depends on the length of the key. The number of combinations possible for the 128-bit is 3.4 x 1038. Therefore, for a standard computer, it will take approximately 500 billion years to launch a complete brute force attack on AES-128.
References
AES encryption | Everything you need to know about AES. (2019, February 4). ProPrivacy.com. Retrieved from https://proprivacy.com/guides/aes-encryption
Khoo, K., Lee, E., Peyrin, T., & Sim, S. M. (2017). Human-readable proof of the related-key security of AES-128. IACR Transactions on Symmetric Cryptology, 59-83.
