How would you describe a challenge-response session?

A workstation or system that generates a random challenge string that the user enters when prompted along with the proper PIN (Personal Identification Number).

A common authentication technique whereby an individual is prompted (the challenge) to provide some private information (the response). Most security systems that rely on smart cards are based on challenge-response. A user is given a code (the challenge) which he or she enters into the smart card. The smart card then displays a new code (the response) that the user can present to log in. Reference: https://www.webopedia.com/TERM/C/challenge_response.html