Advanced Cryptographic Mechanisms BDC Practice Questions (Page 4)

Questions 16–20

1. 16expert · hard

   A voting system must ensure voter privacy while also allowing each voter to verify that their vote was counted. The system is expected to handle a large number of voters, and the verification process must not reveal the voter's choice. Which cryptographic approach best meets these requirements?

   • AUse a homomorphic encryption scheme to tally votes, and provide each voter with a zero-knowledge proof that their vote was included.
   • BUse a simple hash of each vote, published on-chain, and allow voters to compare hashes.
   • CUse a ring signature to anonymize the voter, and publish the vote in plaintext.
   • DUse a digital signature from each voter, with the vote encrypted and stored on-chain.
   Reveal Solution Discussion Select an answer first
2. 17foundation · easy

   Which of the following best describes the scope of advanced cryptographic mechanisms in blockchain security?

   • AThey cover data integrity, authentication, privacy, and secure multi-party computation across the blockchain stack
   • BThey focus exclusively on encrypting network traffic between nodes
   • CThey are limited to generating public and private key pairs for wallet addresses
   • DThey apply only to the consensus layer to secure block validation
   Reveal Solution Discussion Select an answer first
4. 18application · medium

   A supply-chain consortium records product provenance on a blockchain. Each participant signs their own transactions. Later, a regulator needs to verify that a specific transaction was indeed signed by a particular participant. The participant's public key is available. What should the regulator do?

   • ACheck the transaction's timestamp against the participant's activity log
   • BDecrypt the transaction using the participant's private key
   • CCompare the transaction hash with the participant's public key hash
   • DVerify the digital signature using the participant's public key
   Reveal Solution Discussion Select an answer first
5. 19expert · hard

   A developer is implementing a confidential transaction scheme on a public blockchain. The requirement is that transaction amounts are hidden, but the network must be able to verify that no transaction creates money out of thin air (i.e., inputs >= outputs). Which cryptographic tool is most appropriate?

   • ASimple SHA-256 hashes of the amounts
   • BSymmetric encryption of the amounts with a shared key
   • CHomomorphic commitments with range proofs
   • DDigital signatures on the amounts
   Reveal Solution Discussion Select an answer first
6. 20application · medium

   A developer is implementing a blockchain-based auction system. Bidders must submit their bids confidentially, but after the auction closes, the winning bid must be publicly verifiable. Which approach should be used?

   • ABidders commit to their bids by publishing a hash, then reveal the bid after the auction closes
   • BBidders sign their bids and publish them immediately
   • CBidders send their bids to a trusted third party who reveals the winner
   • DBidders encrypt their bids with the auctioneer's public key
   Reveal Solution Discussion Select an answer first