Two servers need to establish a shared symmetric key over an untrusted network. They currently use a pre-shared key that was distributed out-of-band. The administrator wants to move to a protocol that provides forward secrecy. Which protocol should they use?

Diffie-Hellman with a fixed prime and generator

AES-256-GCM with the existing pre-shared key

RSA key exchange with a static server key

A penetration tester finds that a web application generates RSA keys using a predictable seed based on the current timestamp. What is the most likely impact?

An attacker can predict the private key and decrypt or forge signatures.

The keys will be too short to be secure.

The keys will expire immediately.

The keys will be rejected by browsers due to weak algorithms.

A penetration tester is assessing a custom authentication protocol. The server sends a challenge to the client, and the client responds with a digital signature over the challenge using its private key. The server verifies the signature using the client's public key. Which property does this protocol provide?

Authentication and non-repudiation

Confidentiality of the challenge

A penetration tester is examining a system that uses RSA to sign software updates. The tester discovers that the system uses the same RSA key pair for both signing updates and encrypting data sent to the server. Which risk does this pose?

The hash algorithm used in the signature is weak.

An attacker who can trick the server into signing a chosen message can recover the private key.

The key pair is too small to provide adequate security.

The signature can be used to decrypt data.

A network administrator is investigating a suspected man-in-the-middle attack on a legacy system that uses unauthenticated Diffie-Hellman key exchange. What is the most effective mitigation?

Use a static Diffie-Hellman key pair for all sessions.

Switch to AES encryption after the key exchange.

Implement mutual authentication of the key exchange messages using digital signatures.

Increase the Diffie-Hellman prime size to 4096 bits.

GIAC Exploit Researcher and Advanced Penetration Tester

Domain 4Objective 1

Practical Cryptography GXPN Practice Questions (Page 8)

Part of the Offensive Scripting and Cryptography domain, which makes up ~18% of our current practice bank. GIAC (SANS) does not publish an official question count, but from its 180-minute exam (~70–120 total, ~13–22 in this domain), expect 7–11 from this objective — we provide 48 practice questions to prepare you well beyond it. (estimate)

48questions here

10free pages

8concepts

Questions 36–40

36application · medium
Two servers need to establish a shared symmetric key over an untrusted network. They currently use a pre-shared key that was distributed out-of-band. The administrator wants to move to a protocol that provides forward secrecy. Which protocol should they use?
Select an answer first
37application · medium
A penetration tester finds that a web application generates RSA keys using a predictable seed based on the current timestamp. What is the most likely impact?
Select an answer first
38application · medium
A penetration tester is assessing a custom authentication protocol. The server sends a challenge to the client, and the client responds with a digital signature over the challenge using its private key. The server verifies the signature using the client's public key. Which property does this protocol provide?
Select an answer first
39application · hard
A penetration tester is examining a system that uses RSA to sign software updates. The tester discovers that the system uses the same RSA key pair for both signing updates and encrypting data sent to the server. Which risk does this pose?
Select an answer first
40application · medium
A network administrator is investigating a suspected man-in-the-middle attack on a legacy system that uses unauthenticated Diffie-Hellman key exchange. What is the most effective mitigation?
Select an answer first

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