Challenge-response authentication is a family of protocols in which one party presents a question ("challenge") and another party must provide a valid answer ("response") to be authenticated.
Challenge-response authentication is a family of protocols in which one party presents a question ("challenge") and another party must provide a valid answer ("response") to be authenticated. Many cryptographic solutions involve two-way authentication, where both the user and the system must each convince the other that they know the shared secret (the password), without this secret ever being transmitted in the clear over the communication channel, where eavesdroppers might be lurking.
