I am trying to solve the next question:
A client needs authenticate to a server. The client and a system share the server public-key. Denoted here as K. The client sends to the system a message requiring an authentication, and the server responds with a nonce. What does the client send to the server as respost in order to prevent replay attack
- The result of encrypt a nonce with symmetric cryptography and a key K.
- The result of sum K to the nonce.
- A OK message
- The result of encrypt a nonce with asymmetric cryptography and a key K.
- The digest of the nonce
Could you help me with this question please?. For me this question is strange because (1) and (2). Specifically, I think that I do not need to send any key K to the server because this key is a public key. Thus, I think the respost is or (2) or (5). Could you help me, please?