The Advanced Encryption Standard is a subset of which algorithm?

The Advanced Encryption Standard (AES) is specifically derived from the Rijndael algorithm, which was selected as the standard by the National Institute of Standards and Technology (NIST) in 2001. Rijndael was designed by Belgian cryptographers Vincent Rijmen and Joan Daemen, and it supports block sizes of 128, 192, and 256 bits, with key sizes of 128, 192, or 256 bits, which align with the requirements for AES.

Rijndael's design and its structure allowed it to become an effective standard for secure data encryption. The architecture of the AES is based on a substitution-permutation network (SPN), which enhances its resistance to various forms of cryptanalysis. Thus, stating that AES is a subset of Rijndael correctly reflects the historical and technical relationship between the two, as AES is essentially a specific implementation of the broader Rijndael algorithm.

The other options—Blowfish, Twofish, and Serpent—are separate encryption algorithms and do not have the necessary connection to AES as Rijndael does. Each of these algorithms has its own design characteristics and was independently developed, without being the basis for the Advanced Encryption Standard.