Cryptographic Principles and Their Role in Blockchain BBLC Practice Questions (Page 9)

Questions 41–43

1. 41expert · hard

   A blockchain consortium is planning a 10-year roadmap. They are aware that quantum computers could eventually break ECC-based signatures. They need to choose a migration strategy that balances immediate security with future-proofing, while minimizing disruption to existing users. Which approach is the most prudent?

   • AImmediately switch all users to post-quantum signatures (e.g., lattice-based) to be fully prepared.
   • BIgnore quantum threats because they are decades away and current algorithms are secure.
   • CMaintain current ECC but add a quantum-resistant hash-based signature as an optional second signature for high-value transactions.
   • DIncrease ECC key sizes to 512 bits to make them quantum-resistant.
   Reveal Solution Discussion Select an answer first
2. 42application · medium

   A hardware wallet manufacturer is designing a new device for storing cryptocurrency keys. They want to maximize security while keeping the device affordable and energy-efficient. Which design choice is most aligned with these goals?

   • AGenerate keys using a software random number generator on the host computer to reduce hardware complexity.
   • BStore the private key in a plain text file on the device's flash memory for easy backup.
   • CUse a 256-bit ECC key pair, which provides strong security with smaller key sizes and lower computational overhead, making it ideal for low-power devices.
   • DUse a 2048-bit RSA key pair for each wallet, because it is the industry standard for secure hardware.
   Reveal Solution Discussion Select an answer first
3. 43expert · hard

   A blockchain project uses ECC-based signatures. A security audit warns that quantum computers could eventually break ECC. The project wants to migrate to post-quantum signatures without disrupting existing users. Which migration strategy is most appropriate?

   • AUse a longer hash function for signatures
   • BIntroduce a hybrid signature scheme that includes both ECC and a post-quantum algorithm, and support both during a transition period
   • CKeep ECC but increase the key size to 512 bits
   • DImmediately switch the entire network to a post-quantum signature algorithm and require all users to generate new keys
   Reveal Solution Discussion Select an answer first