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300-730 · Question #69
300-730 Question #69: Real Exam Question with Answer & Explanation
The correct answer is C: digital signature. ECDH and ECDSA are elliptic curve algorithms that serve complementary security functions: ECDSA provides digital signatures and ECDH provides key exchange, covering authentication and secure key establishment respectively.
Question
What are two functions of ECDH and ECDSA? (Choose two.)
Options
- Anonrepudiation
- Brevocation
- Cdigital signature
- Dkey exchange
- Eencryption
Explanation
ECDH and ECDSA are elliptic curve algorithms that serve complementary security functions: ECDSA provides digital signatures and ECDH provides key exchange, covering authentication and secure key establishment respectively.
Common mistakes.
- A. Nonrepudiation is a security property that results from using ECDSA signatures, but it is the outcome of digital signing rather than a distinct cryptographic function performed by the algorithm.
- B. Certificate revocation is managed by external PKI mechanisms such as CRL (Certificate Revocation List) or OCSP and is not a function performed by either ECDH or ECDSA.
- E. Neither ECDH nor ECDSA directly encrypts data - ECDH produces a shared secret used to derive symmetric encryption keys, and ECDSA only signs and verifies; bulk encryption is performed by separate symmetric algorithms such as AES.
Concept tested. ECDH key exchange and ECDSA digital signature functions
Reference. https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.186-5.pdf
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