Cryptography-based Designs One-time passwords Each password is used only once Defend against adversary who can eavesdrop and later impersonate Challenge-response Send a response related to the password and a challenge Zero-knowledge proof of knowledge Prove knowledge of a value without revealing it (Out of scope) 12Cryptography-based Designs • One-time passwords • Each password is used only once • Defend against adversary who can eavesdrop and later impersonate • Challenge-response • Send a response related to the password and a challenge • Zero-knowledge proof of knowledge • Prove knowledge of a value without revealing it (Out of scope) Topic 3: User Authentication 122/3/2021