under the subsection on the motivation for the Feistel cipherstructure, it was stated that, for a block of bits, the number of differentreversible mappings for the ideal block cipher is .
Justify.b. In that same discussion, it was stated that for the ideal block cipher, which allows allpossible reversible mappings, the size of the key is bits. But, if there are 2n n * 2 ! n2n!n98 CHAPTER 3 / BLOCK CIPHERS AND THE DATA ENCRYPTION STANDARDpossible mappings, it should take bits to discriminate among the differentmappings, and so the key length should be . However, .Explain the discrepancy