Exponential Ciphers - Introduction to Cryptography with Java Applets - page 277

FIGURE 14.3

EXERCISES

1. Write a pohligHellmanEncipherWCFB() and pohligHellmanDecipherWCFB() method

in the Ciphers class to use CFB.

2. Write the elGamalEncipher() and elGamalDecipher() methods in the Ciphers class.

3. Write the RSAEncipherWCBC() and RSADecipherWCBC() methods in the Ciphers

class to use CBC.

4. Write a Java program to retrieve ElGamal messages using the equal enciphering expo-

nent attack.

5. Write a Java program to retrieve RSA messages when all entities use the same small

encryption exponent.

6. It has been proposed that each entity using RSA use a common modulus (but distinct

encryption and decryption exponents). Why is it crucial that each entity choose its own
modulus?