Cryptographic Hash Functions and Their Uses BDC Practice Questions (Page 6)

Questions 26–30

1. 26foundation · easy

   Why is slow hashing important for password storage?

   • AIt increases the time required for an attacker to brute-force passwords
   • BIt makes the hash output longer, providing more security
   • CIt prevents the hash from being reversed
   • DIt ensures that the same password always produces the same hash
   Reveal Solution Discussion Select an answer first
2. 27foundation · easy

   Which of the following is a common use of cryptographic hash functions?

   • AGenerating symmetric keys from a password without any additional processing
   • BCompressing data to reduce storage space without loss of information
   • CEncrypting data so that it can be decrypted later with a key
   • DVerifying data integrity by comparing hash values before and after transmission
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4. 28expert · hard

   A blockchain protocol uses a hash-based message authentication code (HMAC) constructed as H(key || message) with SHA-256. A security researcher identifies a length-extension vulnerability. The team must choose a mitigation that preserves performance and backward compatibility. Which option is the most secure and practical?

   • AUse SHA-256d (double SHA-256) by hashing the output again.
   • BUse SHA-512 instead of SHA-256.
   • CAdd a fixed suffix to the message before hashing.
   • DSwitch to HMAC-SHA-256, which uses the standard HMAC construction with two nested hashes.
   Reveal Solution Discussion Select an answer first
5. 29application · medium

   A development team is choosing a hash function for a new blockchain protocol that must be resistant to length-extension attacks and provide a different construction than SHA-256. Which algorithm best meets this requirement?

   • ASHA-512
   • BRIPEMD-160
   • CSHA-3 (Keccak)
   • DMD5
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6. 30expert · hard

   A security architect is designing a password storage system for a high-security application. They must choose between using Argon2id with a high memory cost and using bcrypt with a high cost factor. The system runs on commodity hardware and must support many concurrent logins. What is the most important trade-off to consider?

   • Abcrypt is faster, so it is always the better choice for high-traffic systems.
   • Bbcrypt is more secure because it uses a longer salt.
   • CArgon2id provides better resistance to GPU-based attacks but uses more memory, which could reduce concurrent login capacity.
   • DArgon2id is not suitable for password storage because it is not a standard algorithm.
   Reveal Solution Discussion Select an answer first