Advanced Cryptographic Mechanisms BDC Practice Questions (Page 5)

Questions 21–25

1. 21application · medium

   A blockchain startup is designing a private consortium network for healthcare claims. They need to ensure that only authorized regulators can read the claim details, while the participating hospitals must be able to verify the integrity of the claims without seeing the underlying patient data. Which cryptographic approach should the architect recommend?

   • ACommit to each claim using a hash, and use a zero-knowledge proof to allow hospitals to verify the commitment without revealing the claim.
   • BPublish the claim data in an encrypted form on-chain and rely on the blockchain's immutability to prove integrity.
   • CEncrypt the claim data with a symmetric key, and give the key only to regulators.
   • DUse a public-key signature over the hash of each claim, and share the hash with all hospitals.
   Reveal Solution Discussion Select an answer first
2. 22application · medium

   A blockchain developer is designing a permissioned network for a consortium of banks. Each bank runs a validator node, and transactions must be signed by the submitting bank. The consortium requires that any validator can verify a transaction's signature without needing to contact the issuing bank, and that signatures cannot be repudiated. Which cryptographic mechanism should the developer use?

   • AHash-based message authentication code (HMAC) using a per-bank key
   • BRSA encryption of the transaction payload
   • CElliptic curve digital signatures (ECDSA) with each bank's private key
   • DSymmetric encryption with a shared secret among all banks
   Reveal Solution Discussion Select an answer first
4. 23application · medium

   A healthcare research consortium wants to allow researchers to run statistical analyses on patient data without exposing the raw data. The data is stored encrypted, and the researchers need to compute averages and correlations. Which approach should be used?

   • AProvide researchers with the decryption key and rely on a data-use agreement.
   • BUse a zero-knowledge proof to show the statistics are correct without revealing data.
   • CUse homomorphic encryption to compute statistics on encrypted data.
   • DPublish anonymized data and allow researchers to compute statistics.
   Reveal Solution Discussion Select an answer first
5. 24application · medium

   A blockchain network uses a proof-of-work consensus. An attacker with significant computational power wants to rewrite history by creating a longer alternative chain. Which cryptographic property of the blockchain makes this attack difficult but not impossible?

   • AThe use of a centralized timestamp server
   • BThe computational difficulty of finding a nonce that satisfies the target hash
   • CThe use of digital signatures on each transaction
   • DThe encryption of all transaction data
   Reveal Solution Discussion Select an answer first
6. 25application · medium

   A supply-chain consortium wants to prove to auditors that a specific batch of goods was stored at a certain temperature range throughout its journey, without revealing the actual temperature readings or the locations of the sensors. Which advanced cryptographic mechanism best fits this requirement?

   • AHomomorphic encryption over the temperature readings, allowing the auditor to compute the range directly.
   • BA zero-knowledge range proof that the temperature stayed within the required bounds.
   • CA Merkle tree of the readings, with the root hash published on-chain.
   • DA digital signature from each sensor over the raw readings, stored on-chain.
   Reveal Solution Discussion Select an answer first