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Challenge-response authentication - Glossary | MDN 1/3 https://developer.mozilla.org/en-US/docs/Glossary/Challenge reference web, html, css, javascript, documentation 2026-05-05T05:27:14.858945+00:00 kb-cron

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  1. Glossary
  2. Challenge-response authentication

Challenge-response authentication

In security protocols, a challenge is some data sent to the client by the server in order to generate a different response each time. Challenge-response protocols are one way to fight against replay attacks where an attacker listens to the previous messages and resends them at a later time to get the same credentials as the original message. The HTTP authentication protocol is challenge-response based, though the "Basic" protocol isn't using a real challenge (the realm is always the same).

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