Cryptographic Hash Functions and Their Uses BDC Practice Questions (Page 8)

Questions 36–40

1. 36expert · hard

   A cloud storage provider wants to detect data corruption in large files. They currently store a single SHA-256 hash per file. They are considering using a Merkle tree to improve efficiency. What is the primary benefit of using a Merkle tree over a single hash?

   • AIt reduces the storage space needed for integrity metadata.
   • BIt eliminates the need to rehash the file after any modification.
   • CIt allows detecting and locating which chunk of a large file is corrupted.
   • DIt makes the hash computation faster.
   Reveal Solution Discussion Select an answer first
2. 37application · medium

   A developer is implementing a content-addressable storage system where files are identified by their SHA-256 hash. A user uploads a file, and the system stores it under the hash of its content. Which property of the hash function makes this system work correctly?

   • APreimage resistance ensures that the file content cannot be derived from its hash.
   • BThe avalanche effect ensures that similar files have very different addresses, improving lookup performance.
   • CDeterminism ensures that the same file always has the same address, which is necessary but not sufficient for correctness.
   • DCollision resistance ensures that two different files do not share the same address, preventing data corruption.
   Reveal Solution Discussion Select an answer first
4. 38application · medium

   A QA engineer is testing a hash function's avalanche effect. They hash a 1 KB file, then flip a single bit in the file and hash it again. What should they observe to confirm the avalanche effect?

   • AThe new hash is longer than the original hash.
   • BThe new hash is exactly the same as the original hash.
   • CThe new hash is shorter than the original hash.
   • DApproximately half of the bits in the new hash differ from the original hash.
   Reveal Solution Discussion Select an answer first
5. 39expert · hard

   A blockchain protocol uses a Merkle tree to commit to a large set of transactions. A new requirement demands that users be able to prove that a transaction is NOT included in a block. Which approach is most efficient?

   • AUse a standard unsorted Merkle tree and provide a random path.
   • BUse a sorted Merkle tree and provide the two adjacent transactions as proof of non-inclusion.
   • CProvide all transactions in the block as proof.
   • DProvide the Merkle root and ask the verifier to trust it.
   Reveal Solution Discussion Select an answer first
6. 40foundation · easy

   What is a key characteristic of the SHA-3 family of hash functions compared to SHA-2?

   • ASHA-3 is faster than SHA-2 on all hardware
   • BSHA-3 is an encryption algorithm, not a hash function
   • CSHA-3 produces a variable-length output that can be any size
   • DSHA-3 is based on a sponge construction, while SHA-2 uses a Merkle–Damgård structure
   Reveal Solution Discussion Select an answer first