AES is based on a design principle known as a Substitution-permutation network, the combination of both substitution and permutation, and is fast in both software and hardware. Unlike its predecessor DES, AES system does not use a Feistel network. AES Rijndael is a variant that has a fixed block size of 128 bits and a key size of 128, 192, and 256 bits. In contrast, the specification of the Rijndael block itself is specified and main dimensions, may be any multiple of the bit 32, so the minimum 128 and maximum 256 bits. AES operates a system of order 4 by 4 bytes column-major.
Key size used for AES cipher specifies the number of repetitions of transformation rounds that convert the input plaintext called the final result, called ciphertext. The number of repeat cycles are as follows: Fourteen cycles of repetition for 256 bit keys. twelve cycles of repetition for 192-bit keys. ten cycles of repetition for 128 bit keys. Each round consists of several stages of processing, each round consists of four similar, but differing in one step depending on the encryption key itself. In one set of reverse rounds are applied to transform ciphertext back into plaintext then the original using the same encryption key. TV Packages in AES encription: TPS