Question

__________ use a challenge response mechanism in which a server challenges a user with a number, which a user must then enter into a device to calculate the response number.

Answer 1

Answer: Authentication

Explanation:

 Authentication is the mechanism of the challenge response in which it basically allow the server to challenge the user with the number without revealing any password.

Then the user must enter that particular password to enter into the device for calculating the particular response number. Then it basically compute the given response by apply hash function in the server challenge that combine the users password.