Describe the public key authentication process, assuming that the keys are all stored in the appropriate places.

Question

What will be an ideal response?

Answer 1

With the keys stored in the appropriate places, the following occurs in the public key authentication process:
1. The client informs the server which public key is being used for authentication.
2. The server checks to see if the public key is known.
3. The server encrypts a random number using the public key and transfers this to the client.
4. Only the client is able to decrypt the random number with its private key.
5. The client sends the server an MD5 checksum that it has calculated from the number.
6. The server also calculates a checksum and, if they are identical, the user has authenticated successfully.
7. If public key authentication fails and password authentication is allowed, the user is asked for the login password.