AES-256

AES using a 256-bit key, the strongest standard AES variant.

AES-256 is the AES variant that uses a 256-bit key, offering the largest standard key size and the widest margin against brute-force attacks, which is why it appears in high-assurance and government contexts. The larger key means more internal rounds and slightly more computation than AES-128, yet the performance difference is usually negligible on modern hardware. A common exam misconception is that a longer key fixes every weakness; mode of operation and key management still determine real-world security regardless of key length.