Hashing algorithms (SHA, MD5) in Cybersecurity - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Hash Function Output Lengths

Which of the following correctly describes the output length of the MD5 and SHA-256 hashing algorithms?

A MD5 produces a 128-bit hash, while SHA-256 produces a 256-bit hash.

B MD5 produces a 256-bit hash, while SHA-256 produces a 128-bit hash.

C Both MD5 and SHA-256 produce 256-bit hashes.

D Both MD5 and SHA-256 produce 128-bit hashes.

💡 Hint

Think about the number in the SHA-256 name and the standard output size of MD5.

MD5 outputs a 128-bit (16-byte) hash. SHA-256 outputs a 256-bit (32-byte) hash, which is twice as long, providing stronger security.

📋 Factual

intermediate

Collision Resistance in Hashing

Which statement best explains the concept of collision resistance in hashing algorithms like SHA and MD5?

A It means it is impossible for two different inputs to produce the same hash output.

B It means it is computationally infeasible to find two different inputs that produce the same hash output.

C It means the hash output is always unique for every input without exception.

D It means the hash function can be reversed to find the original input.

💡 Hint

Consider what 'computationally infeasible' means compared to 'impossible'.

Collision resistance means that while collisions can theoretically exist, it is extremely hard to find two different inputs with the same hash output using current computing power.

🔍 Analysis

advanced

Security Risks of MD5

Given that MD5 is widely considered insecure today, what is the main reason for this status?

A MD5 is vulnerable to collision attacks, allowing attackers to create different inputs with the same hash.

B MD5 hashes can be easily reversed to reveal the original input.

C MD5 hashes are too long, making them inefficient for modern systems.

D MD5 uses outdated encryption keys that can be cracked with brute force.

💡 Hint

Think about what collision attacks mean for hash security.

MD5 is vulnerable to collision attacks, meaning attackers can find two different inputs that produce the same hash, undermining its reliability for security.

❓ Comparison

advanced

Comparing SHA-1 and SHA-256

Which of the following correctly compares SHA-1 and SHA-256 in terms of security and output size?

A SHA-1 produces a 256-bit hash and is less secure than SHA-256 which produces a 160-bit hash.

B SHA-1 produces a 160-bit hash and is more secure than SHA-256.

C SHA-1 and SHA-256 both produce 256-bit hashes but SHA-1 is faster.

D SHA-1 produces a 160-bit hash but is less secure than SHA-256, which produces a 256-bit hash.

💡 Hint

Recall the bit lengths and known vulnerabilities of SHA-1.

SHA-1 outputs 160 bits but has known vulnerabilities making it less secure. SHA-256 outputs 256 bits and is currently considered secure.

❓ Reasoning

expert

Choosing a Hashing Algorithm for Password Storage

You need to store user passwords securely in a database. Which hashing algorithm choice is best and why?

A Use SHA-256 because it is more secure than MD5 and widely used.

B Use SHA-1 because it balances speed and security well.

C Use a specialized password hashing algorithm like bcrypt or Argon2 instead of MD5 or SHA variants.

D Use MD5 because it is fast and widely supported.

💡 Hint

Think about what makes password hashing different from general hashing.

MD5, SHA-1, and SHA-256 are general-purpose hashes and are fast, which makes them vulnerable to brute-force attacks. Specialized algorithms like bcrypt or Argon2 are designed to be slow and include features like salting, making them better for password storage.