Encryption and decryption algorithms

1. Differentiate DES and double DES.

2. What is PRNG?

3. Write short notes on linear congruential generator.

4. Write Blum Blum Shub (BSS) generator algorithm. Give an example.

Q19;

1. Explain about RC4 key scheduling, encryption and decryption algorithms in detail.

2. Generate a key stream using RC4 for a simple 4-byte example, where 8 = {0, 1, 2, 3}, Key = {11, 13, 15, 17} and i =j= 0.