Explanation:
If the sender sends both a message and a message hash encrypted by its private key, then the receiver can apply the sender’s public key to the hash and get the message hash. The receiver can apply the hashing algorithm to the message received and generate a hash. By matching the generated hash with the one received, the receiver is ensured that the message has been sent by the specific sender, i.e., authenticity, and that the message has not been changed enroute.
Authenticity and privacy will be ensured by first using the sender’s private key and then the receiver’s public key to encrypt the message. Privacy and integrity can be ensured by using the receiver’s public key to encrypt the message and sending a message hash/digest. Only nonrepudiation can be ensured by using the sender’s private key to encrypt the message. The sender’s public key, available to anyone, can decrypt a message; thus, it does not ensure privacy.