In Dual Watermarking in Tele-radiology using DWT for Data Authentication and Security, the authors wrote:
The encryption process uses the Feistel structure consisting multiple rounds for processing the plaintext to obtain the cipher text and each round consisting of a “substitution” followed by a permutation step. In this paper dual watermarking algorithm for patient detail encryption is used along with the key which uses a block cipher algorithm. Advanced Encryption Standard (AES) is a very powerful block cipher algorithm compared to the data encryption standard (DES) algorithm. It functions on a block of data at the input side with known size to execute same size of block of data at the output side. In this proposed system, the input blocks and output block data reserved is 128 bits of fixed length each. A symmetric key along with block cipher is taken where input to block cipher is AES. The AES encryption algorithm has the following stages of Byte substitution followed by row shifting followed by columns mixing and finally adding round keys.
Here, AES and the Feistel structure are both used. Please explain how this is possible with any kind of flow diagram.
Paper Published by K.Vinothini, S.K. Mydhili, S. Periyanayagi and G. Sukanya, "Dual Watermarking in Tele-radiology..."