Which of the following is an example of a cryptographically secure pseudo-random number generator (CSPRNG)?

Linear congruential generator (LCG)

A company is designing a new cryptographic system and must choose a random number generator. The system will run on embedded devices with limited entropy sources. Which approach is most appropriate?

Use a simple LCG with a large modulus.

Use a CSPRNG that is periodically reseeded from a hardware entropy source.

Use a Mersenne Twister seeded once at boot.

Use a deterministic PRNG with no reseeding.

A cryptographic library generates Diffie-Hellman private exponents using a PRNG that was seeded with a predictable value (e.g., the system clock). An attacker who knows the seed can predict the private exponents. Which type of attack does this scenario illustrate, and what is the primary mitigation?

A brute-force attack on the prime modulus; mitigation is to use a larger prime.

A side-channel attack on the exponentiation; mitigation is to use constant-time algorithms.

A man-in-the-middle attack; mitigation is to authenticate the public values.

A state-compromise attack on the PRNG; mitigation is to use a CSPRNG with high-entropy seeding and periodic reseeding.

What is the primary purpose of the Diffie-Hellman key exchange protocol?

To authenticate the identity of the communicating parties

To allow two parties to agree on a shared secret over an insecure channel

To encrypt and decrypt data using a shared symmetric key

To generate a digital signature for a message

A protocol uses Diffie-Hellman with a static private key for a server. The server's private key is compromised. Which sessions are at risk?

All past and future sessions that used that static key.

No sessions, because Diffie-Hellman is secure.

Only sessions where the attacker was present during the exchange.

EC-CouncilCertified Encryption Specialist

Domain 3Objective 3

Diffie-Hellman Key Exchange and Random Number Generators ECES Practice Questions (Page 1)

Part of the Asymmetric Cryptography and Number Theory domain, which makes up ~17% of our current practice bank. EC-Council does not publish an official question count, but from its 120-minute exam (~50–80 total, ~9–14 in this domain), expect 3–5 from this objective — we provide 40 practice questions to prepare you well beyond it. (estimate)

40questions here

8free pages

7concepts

Questions 1–5

1foundation · easy
Which of the following is an example of a cryptographically secure pseudo-random number generator (CSPRNG)?
Select an answer first
2expert · hard
A company is designing a new cryptographic system and must choose a random number generator. The system will run on embedded devices with limited entropy sources. Which approach is most appropriate?
Select an answer first
3application · medium
A cryptographic library generates Diffie-Hellman private exponents using a PRNG that was seeded with a predictable value (e.g., the system clock). An attacker who knows the seed can predict the private exponents. Which type of attack does this scenario illustrate, and what is the primary mitigation?
Select an answer first
4foundation · easy
What is the primary purpose of the Diffie-Hellman key exchange protocol?
Select an answer first
5expert · hard
A protocol uses Diffie-Hellman with a static private key for a server. The server's private key is compromised. Which sessions are at risk?
Select an answer first

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