What do side-channel attacks exploit?

Mathematical weaknesses in the algorithm

Network protocol vulnerabilities

Physical characteristics of the implementation, such as timing or power consumption

A security analyst intercepts a ciphertext message that is known to be a simple substitution cipher. The analyst counts the frequency of each letter in the ciphertext and finds that the letter 'Q' appears 12.7% of the time, while 'Z' appears 1.2%. Based on this frequency distribution, which action is most appropriate?

Assume the cipher is a Caesar shift and shift 'Q' back by 4 to get 'M', then apply the same shift to the entire ciphertext.

Conclude that the cipher is unbreakable because the frequency distribution is too uniform.

Use a known-plaintext attack by guessing that the plaintext starts with 'The' and derive the key from that.

Map 'Q' to 'E' and 'Z' to 'Q' or 'Z' in the plaintext alphabet, then refine the mapping using common digraphs and trigraphs.

What is the defining characteristic of a replay attack?

Capturing a valid transmission and retransmitting it later

Analyzing the frequency of characters

Intercepting and modifying messages in real time

Using a precomputed table of hashes

EC-CouncilCertified Ethical Hacker

Domain 9Objective 3

Cryptanalysis and Attacks CEH Practice Questions (Page 8)

Part of the Cryptography domain, which makes up ~9% of our current practice bank. EC-Council does not publish an official question count, but from its 240-minute exam (~95–160 total, ~9–14 in this domain), expect 2–4 from this objective — we provide 63 practice questions to prepare you well beyond it. (estimate)

63questions here

13free pages

16concepts

16 Concepts in This Objective

Cryptanalysis Fundamentals
Types of Cryptanalytic Attacks
Brute-Force Attack
Dictionary Attack
Rainbow Table Attack
Frequency Analysis
Known-Plaintext Attack
Chosen-Plaintext Attack
Chosen-Ciphertext Attack
Related-Key Attack
Side-Channel Attacks
Man-in-the-Middle Attack
Replay Attack
Birthday Attack
Meet-in-the-Middle Attack
Cryptanalytic Tools and Techniques

Questions 36–40

36foundation · easy
What do side-channel attacks exploit?
Select an answer first
37application · medium
A security analyst intercepts a ciphertext message that is known to be a simple substitution cipher. The analyst counts the frequency of each letter in the ciphertext and finds that the letter 'Q' appears 12.7% of the time, while 'Z' appears 1.2%. Based on this frequency distribution, which action is most appropriate?
Select an answer first
38foundation · easy
Which tool is commonly used for password cracking and supports dictionary, brute-force, and hybrid attacks?
Select an answer first
39foundation · easy
What is the defining characteristic of a replay attack?
Select an answer first
40application · medium
A security engineer is evaluating the security of a digital signature scheme that uses a 128-bit hash function. The engineer wants to assess the feasibility of a birthday attack to create a collision. Approximately how many hash computations are needed to find a collision with a probability of about 50%?
Select an answer first

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Cryptanalysis and Attacks CEH Practice Questions (Page 8)

Questions 36–40

What do side-channel attacks exploit?

Which tool is commonly used for password cracking and supports dictionary, brute-force, and hybrid attacks?

What is the defining characteristic of a replay attack?

Keep studying — Cryptography