CEH Practice Question: Advanced Topics: Wireless, Cloud, IoT, Cryptography
Which of the following cryptographic hash functions is known to be vulnerable to collision attacks and should be avoided for security applications?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
MD5
MD5 is known to be vulnerable to collision attacks, making it unsuitable for security applications like digital signatures.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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RIPEMD-160
Why it's wrong here
RIPEMD-160 is a 160-bit cryptographic hash function developed in the framework of the European RACE project. While it is considered cryptographically secure with no known practical collision or pre-image attacks, its adoption is less widespread compared to the SHA family. Therefore, it is not the correct answer for a 'broken' hash function, as it remains secure for its intended purpose.
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MD5
Why this is correct
MD5, or Message-Digest Algorithm 5, is a widely known cryptographic hash function that produces a 128-bit hash value. It is definitively considered cryptographically broken due to the discovery of practical collision attacks, notably demonstrated in 2004. These vulnerabilities mean MD5 can no longer reliably guarantee data integrity or be used for digital signatures, making it unsuitable for secure applications.
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SHA-256
Why it's wrong here
SHA-256 is a member of the Secure Hash Algorithm 2 (SHA-2) family, generating a 256-bit hash value. It is currently considered cryptographically secure and is widely recommended for various security applications, including digital signatures, password hashing, and blockchain technologies. Its robust design provides strong collision and pre-image resistance, making it a reliable choice for modern cryptographic needs.
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SHA-1
Why it's wrong here
SHA-1, a 160-bit hash function, has known theoretical and practical collision vulnerabilities, with the first public collision demonstrated in 2017. Although it is stronger than MD5, these attacks have led to its deprecation for most security-critical applications. Consequently, while not as trivially broken as MD5, it is no longer considered secure enough for new designs and is being phased out.
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Same concept, more angles
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Variation 1. Which of the following is the PRIMARY reason that MD5 is no longer recommended for use in digital signatures?
medium- A.MD5 is a symmetric algorithm, not a hash function
- B.MD5 is computationally too slow for large data
- C.MD5 produces a 128-bit hash, which is too short for modern security
- ✓ D.MD5 is vulnerable to collision attacks
Why D: MD5 is vulnerable to collision attacks, where two different inputs produce the same hash. This undermines the integrity and non-repudiation properties required for digital signatures.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CEH practice question is part of Courseiva's free EC-Council certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CEH exam.