Advanced Cryptographic Mechanisms in Blockchain Security BBLC Practice Questions (Page 9)

Questions 41–45

1. 41expert · hard

   A blockchain wallet provider wants to allow users to recover their funds if they lose their private key. They are considering a multi-signature scheme where multiple devices hold different keys. What is the primary security benefit of this approach?

   • AIt increases the speed of transaction signing.
   • BIt reduces the risk of a single point of failure for key loss or theft.
   • CIt makes the public key harder to derive from the private key.
   • DIt eliminates the need for a backup of the private key.
   Reveal Solution Discussion Select an answer first
2. 42application · medium

   A blockchain developer is designing a system where each block contains a hash of the previous block's header. An attacker modifies a transaction in an old block. Which property of the hash chain ensures the modification is detected?

   • AAvalanche effect: any change in input produces a completely different hash output.
   • BCollision resistance: two different inputs cannot have the same hash.
   • CSecond preimage resistance: it is hard to find another input with the same hash.
   • DPreimage resistance: it is impossible to find the original input from the hash.
   Reveal Solution Discussion Select an answer first
4. 43application · medium

   A blockchain block contains 1,024 transactions. A light client wants to verify that transaction #500 is included in the block. Using a Merkle tree, how many hash operations does the client need to perform?

   • A10 hash operations, one for each level of the tree.
   • B1,024 hash operations, one for each transaction.
   • C1 hash operation, just the root hash.
   • D512 hash operations, half the transactions.
   Reveal Solution Discussion Select an answer first
5. 44foundation · easy

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

   • ABoth keys are generated independently and then paired
   • BThe public key is derived from the private key using a one-way function
   • CThe private key is derived from the public key using a hash function
   • DThe private key is the hash of the public key
   Reveal Solution Discussion Select an answer first
6. 45foundation · easy

   What is the defining property of homomorphic encryption?

   • AIt generates a new key for each encryption operation
   • BIt is a hashing algorithm that produces a fixed-size output
   • CIt uses the same key for encryption and decryption
   • DIt allows computations to be performed on encrypted data without decrypting it
   Reveal Solution Discussion Select an answer first