Cryptographic Principles and Their Role in Blockchain BBLC Practice Questions (Page 3)

Questions 11–15

1. 11foundation · easy

   In a Merkle tree, what does the Merkle root represent?

   • AThe hash of all transactions in the block, combined hierarchically
   • BThe timestamp of the block
   • CThe first transaction in the block
   • DThe private key of the block producer
   Reveal Solution Discussion Select an answer first
2. 12application · medium

   A supply-chain consortium stores shipment records in a blockchain. Each block contains a Merkle root of all transaction hashes. A regulator requests proof that a specific shipment record exists in a particular block, but the regulator should not see the other records in that block. What should the consortium provide?

   • AA digital signature from the consortium over the entire block
   • BThe full list of transactions in the block so the regulator can recompute the Merkle root
   • CThe block header and the regulator's own hash of the shipment record
   • DThe transaction hash, the Merkle root, and the sibling hashes along the path to the root
   Reveal Solution Discussion Select an answer first
4. 13foundation · easy

   In the digital signature verification process, what does the verifier use to check a signature?

   • AThe signer's private key
   • BThe signer's public key
   • CThe transaction's hash only
   • DA shared secret key
   Reveal Solution Discussion Select an answer first
5. 14application · medium

   A blockchain startup is designing a system to store large files off-chain while keeping a verifiable record on-chain. They plan to store only a single hash per file in the ledger. During a security review, an auditor points out that two different files could theoretically produce the same hash, undermining the integrity guarantee. Which property of cryptographic hash functions is the auditor concerned about, and what is the best way to mitigate this risk?

   • ASecond preimage resistance; store both the hash and the file size to make collisions computationally infeasible.
   • BPreimage resistance; use a longer hash output to reduce the chance of a preimage attack.
   • CAvalanche effect; use a hash function that changes output drastically with small input changes to prevent collisions.
   • DCollision resistance; use a hash function with a larger output size (e.g., SHA-256 instead of SHA-1) and consider storing the file's Merkle root if the file is split into chunks.
   Reveal Solution Discussion Select an answer first
6. 15foundation · easy

   In public-key cryptography, what is the relationship between a public key and a private key?

   • AThey are identical and interchangeable
   • BThey are unrelated and generated independently
   • CThe public key is derived from the private key, but the private key cannot be feasibly derived from the public key
   • DThe private key is derived from the public key
   Reveal Solution Discussion Select an answer first