Question

8.17. Considering the four examples from Problem 8.13, we see that the Elgamal scheme is nondeterministic: A given plaintext x has many valid ciphertexts, e.g., both x=33 and x=248 have the same ciphertext in the problem above. 1. Why is the Elgamal signature scheme nondeterministic? 2. How many valid ciphertexts exist for each message x (general expression)? How many are there for the system in Problem 8.13 (numerical answer)? 3. IstheRSA crypto systemnondeterministic once the public key has been chosen?

8.13. Encrypt the following messages with the Elgamal scheme (p = 467 and
α
=
2): 1. kpr =d =105, i=213, x=33 2. kpr =d =105, i=123, x=33 3. kpr =d =300, i=45, x=248 4. kpr =d =300, i=47, x=248 Now decrypt every ciphertext and show all steps.

Answer 1