SSCP Systems Security Certified PractitionerCryptographyEasy
A system administrator needs to securely exchange a symmetric encryption key with a remote user over an insecure channel without prior shared secrets. Which cryptographic protocol is commonly used for this purpose?
- AMD5 (Message-Digest Algorithm 5)
- BAES (Advanced Encryption Standard)
- CRSA (Rivest–Shamir–Adleman)
- DDiffie-Hellman
Show answer & explanationAnswer & explanation
Correct answer: D. Diffie-Hellman
Diffie-Hellman is a key exchange protocol that allows two parties to establish a shared secret key over an insecure communication channel without prior shared secrets.
Why the other options are wrong
- A. MD5 is a hashing algorithm, not used for key exchange or encryption.
- B. AES is a symmetric encryption algorithm, not a key exchange protocol.
- C. RSA can be used for key exchange (encrypting a symmetric key), but Diffie-Hellman is designed specifically for establishing a shared secret over an insecure channel without prior secrets.
Diffie-Hellman Key Exchange
A cryptographic protocol that allows two parties to establish a shared secret key over an insecure communication channel.
- Does not provide authentication by itself.
- Vulnerable to man-in-the-middle attacks without authentication.
- Based on the mathematical difficulty of the discrete logarithm problem.
Memory trick: Need to share a key? Diffie-Hellman's the secret handshake.