1. Compute the md5 hash of "Michael" using openssl.

2. Alice wants to send a message to Bob. Alice and Bob shares a symmetric secret key K. To send the message, Alice encrypts it with K and Bob decrypts it with K upon receipt of a message. A malicious attacker Trudy can listen to the messages sent by Alice.

a) Assuming Trudy does not have access to the key K and cannot break the encrypted messages, can Trudy insert a fake message purporting to be from Alice?

b) Bob claimed that Alice sent the message (I will pay $100). Alice denies sending that. Using the current setup, can Bob prove that Alice sent the message? If yes, how? If no, why?