Data communications module coordinator occasionally sends important messages to his students (changes in the time of exams/learning sessions), the messages don’t carry any confidential information but the integrity and authenticity of the messages are very essential. Outline the steps of a generic protocol to enable the students to authenticate the received messages and to be ensured that the message never modified in the transit.

Sure, here is a generic protocol that can be used to ensure the authenticity and integrity of the messages:

1. Key Generation: The coordinator generates a pair of keys - a private key and a public key. The private key is kept secret by the coordinator, while the public key is distributed to all the students.

2. Message Creation: The coordinator creates the message that needs to be sent to the students.

3. Signing the Message: The coordinator uses his private key to sign the message. This process involves creating a hash of the message and then encrypting the hash with the private key. The result is the digital signature.

4. Sending the Message: The coordinator sends the message along with the digital signature to the students.

5. Verifying the Message: Upon receiving the message and the digital signature, the students first use the coordinator's public key to decrypt the digital signature, getting the original hash. They then create a hash of the received message. If the two hashes match, it means that the message was not modified in transit and it was indeed sent by the coordinator.

6. Acknowledging the Message: After verifying the message, the students can send an acknowledgement back to the coordinator, confirming that they have received and verified the message.

This protocol ensures both the authenticity (since only the coordinator has the private key to sign the message) and the integrity (since any modification in the message would result in a different hash) of the messages.