2. Public Key Cryptography (12 marks): (a) (4 marks) Name and briefly explain the basic mathematical problem that ElGamal is based on. If the attacker can solve this problem what can it calculate that will lead to plaintext recovery? (b) (8 marks) In a public-key system using RSA, you intercept the ciphertext C = 71 sent to a user whose public key is (e = 13, n = 77). Compute the plaintext M. 2. Public Key Cryptography (12 marks): (a) (4 marks) Name and briefly explain the basic mathematical problem that ElGamal is based on. If the attacker can solve this problem what can it calculate that will lead to plaintext recovery? (b) (8 marks) In a public-key system using RSA, you intercept the ciphertext C = 71 sent to a user whose public key is (e = 13, n = 77). Compute the plaintext M