AES128

AES-128, the 128-bit key variant of the Advanced Encryption Standard, is a symmetric-key block cipher that operates on 128-bit blocks and uses a 128-bit key. It is part of the AES family specified by the U.S. National Institute of Standards and Technology (NIST) in 2001 to replace DES. The AES family is based on the Rijndael algorithm, designed by Vincent Rijmen and Joan Daemen.

AES-128 encryption consists of an initial AddRoundKey step, followed by ten rounds. In each round, the state undergoes SubBytes, ShiftRows, MixColumns, and AddRoundKey; the final round omits the MixColumns step. The key schedule expands the 128-bit key into eleven round keys used in the AddRoundKey steps.

Security and usage: AES-128 is widely regarded as secure against current practical cryptanalytic attacks. With a 128-bit key, the best-known attacks are impractical with modern resources. AES-128 is widely deployed in security protocols and standards, including TLS for securing web traffic, IPsec, and Wi-Fi security (WPA2 and WPA3), as well as disk and file encryption systems.

Variants: AES-192 and AES-256 use 12 and 14 rounds, respectively, and require longer keys and more computation. The choice among variants balances performance and security margins; AES-128 is typically chosen for efficiency in resource-constrained environments while maintaining strong security for many applications.