1. What are the essential ingredients of a symmetric encryption scheme?
2. What is cryptanalysis? Summarize the various types of cryptanalytic attacks on encrypted messages.
3. List the parameters of a symmetric block cipher for greater security.
4. What is a block cipher? Name the important symmetric block ciphers.
1. Describe the data encryption algorithm for 64-bit length plaintext and 56-bit length key.
2. Why is the middle portion of triple DES a decryption rather than an encryption?
3. What are the advantages and disadvantages of triple DES?
4. Why is it not desirable to reuse a key in encryption using a stream cipher?