In Challenge-Response authentication the claimant ________.
2018
In Challenge-Response authentication the claimant ________.
Answer: A. Proves that she knows the secret without revealing it — Key idea: The claimant proves knowledge of a secret by producing a correct response to a verifier's challenge without revealing the secret itself. Verifier…
- A.
Proves that she knows the secret without revealing it
- B.
Proves that she doesn’t know the secret
- C.
Reveals the secret
- D.
Gives a challenge
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Correct answer: A
Key idea: The claimant proves knowledge of a secret by producing a correct response to a verifier's challenge without revealing the secret itself.
Verifier generates a fresh challenge (nonce) and sends it to the claimant.
Claimant computes a response using the secret and the challenge, for example response = MAC(secret, challenge), a signature, or encryption.
Claimant sends the response to the verifier.
Verifier checks the response using the shared secret or the claimant's public key; a valid response confirms the claimant knows the secret without exposing it.
Security properties:
Does not reveal the secret: only a value derived from the secret is sent.
Prevents replay attacks: using a fresh challenge (nonce) ensures old responses are invalid.
Role clarity: the verifier issues the challenge; the claimant responds to prove knowledge.
Examples include password-based challenge-response schemes, Kerberos ticket exchanges, and secure remote password protocols (SRP).
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