Challenge-Response Authentication

What Does Challenge-Response Authentication Mean?

Challenge-response authentication is a group or family of protocols characterized by one entity sending a challenge to another entity. The second entity must respond with the appropriate answer to be authenticated.

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A simple example of this is password authentication. The challenge is from a server asking the client for a password to authenticate the client’s identity so that the client can be served.

Techopedia Explains Challenge-Response Authentication

Most smart card systems use challenge-response authentication. These systems require at least two things for authentication and entry: the smart card and the user’s password.

Another challenge-response authentication example is the use of CAPTCHA, a form of reverse-Turing test for the system to determine if the client is a human or not. This is used to prevent spam and auto-registration of new accounts for a website or email.

Biometric systems are another form of challenge-response authentication.

In cryptography, zero-knowledge password proof and key agreement systems such as secure remote password, CRAM-MD5 and secure shell’s challenge-response system based on RSA are considered to be very sophisticated challenge-response algorithms.

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Margaret Rouse

Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…