6. If you want to securely send a vote result to the voting center. Two candidates names are John and Kathy, what encryption mode should you choose from these: ECB, CBC, CFB, OFB. And why? (10 points)

7. Consider the scheme: Alice sends a message M to Bob. To make Bob to verify the content is authentic, Alice made a hash over the message M, i.e., to generate hash(M), and send (M,hash(M)) together to Bob. Assume the message is not encrypted by any other means.

1. Could this scheme protect against transmitting error? (E.g., if a transmitting error happens by flipping a bit or two due to bad link quality, could Bob discover it?) (10 points)
2. Could this scheme protect against an malicious attacker that can intercept and inject into the transmission? Why? (10 points)