(a) Briefly describe what is meant by the wordcryptography.
(b) Briefly describe the Vigenere cipher,including a discussion of the encryption and decryptionprocesses.
(c) Describe what is meant by a ‘FeistelCipher’.
(d) DES includes S-boxes as part of itsencryption and decryption steps. Each of eight S-boxes is a fixed 4× 16 array, whose entries come from the integers 0, 1, . . . , 15.Describe in detail how DES transforms a 48-bit string into a 32-bitstring using the S-boxes.
(e) Without giving details of the algorithm,briefly discuss some of the shortcomings of DES.
THIS QUESTIONS FOR CRYPTOGRAPHY
