challenge-response (thing) by ketaset

A commonly used authentication protocol consisting of the following four steps:

The client sends a message to the server declaring his identity and requests authentication.
The server sends a challenge to the client consisting of some random value x.
The client computes h(password,x) and sends it back as the response. Here h is a hash function with the property that it is essentially impossible to figure out password even if you know both x and h(password,x).
The server also computes h(password,x) and compares it with the response it got from the client.

double opt-in	Why security experts avoid implementing	Authentication	challenge response
Kakinomoto no Hitomaro	OCR	mutual authentication	John Rutter
Hamming code	call and response	Flex	computer security
challenge	ISP	Spartakus and the Sun Beneath the Sea	whitelist
SMTP AUTH	spoof	First Aid	hash
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