a Ideal Block Cipher->Feistel Feistel proposed We can approximate the ideal block cipher by product cipher Develop a block cipher with a key length of k bits and a block length of n bits, allowing a total of 2 possible transformation Rather than 2n 復大辱软件学院 LiSTLiJT 10 Ideal Block Cipher->Feistel • Feistel proposed – We can approximate the ideal block cipher by product cipher; – Develop a block cipher with a key length of k bits and a block length of n bits, allowing a total of 2k possible transformation – Rather than 2n!