Blockchain Developer Fundamentals and Cryptography 3 — Questions and Answers
Question 1: What is a nonce in the context of proof-of-work mining?
- A wallet address
- A value miners vary to find a valid block hash (Correct answer)
- A smart contract function
- A type of token
Correct answer: A value miners vary to find a valid block hash
Miners repeatedly change the nonce until the block hash meets the difficulty target.
Question 2: What does 'immutability' mean for a blockchain ledger?
- Transactions can be edited by miners
- Recorded data cannot be feasibly altered after confirmation (Correct answer)
- The ledger is private
- Blocks have no timestamps
Correct answer: Recorded data cannot be feasibly altered after confirmation
Immutability means confirmed records cannot be changed without redoing all subsequent work.
Question 3: How is a blockchain address typically derived from a public key?
- By encrypting the public key
- By hashing the public key (Correct answer)
- By signing the public key
- By compressing the private key
Correct answer: By hashing the public key
Addresses are usually generated by applying hash functions to the public key.
Question 4: What problem does the Byzantine Generals Problem describe in distributed systems?
- Network latency only
- Achieving agreement despite faulty or malicious participants (Correct answer)
- Storage limits
- Key generation speed
Correct answer: Achieving agreement despite faulty or malicious participants
It describes reaching consensus when some participants may be unreliable or deceptive.
Question 5: What is the role of the previous block hash field in each block?
- It stores the miner reward
- It links blocks into a tamper-evident chain (Correct answer)
- It encrypts transactions
- It sets the difficulty
Correct answer: It links blocks into a tamper-evident chain
Each block references the prior block's hash, chaining them so any change breaks the chain.
Question 6: Which statement about symmetric encryption is correct?
- It uses different keys for encryption and decryption
- It uses the same key for encryption and decryption (Correct answer)
- It requires no key
- It is the same as hashing
Correct answer: It uses the same key for encryption and decryption
Symmetric encryption uses a single shared secret key for both operations.
Question 7: What does ECDSA stand for in blockchain signing?
- Encrypted Chain Data Storage Algorithm
- Elliptic Curve Digital Signature Algorithm (Correct answer)
- Electronic Code Distribution Standard Authority
- Extended Cryptographic Data Signature API
Correct answer: Elliptic Curve Digital Signature Algorithm
ECDSA is the Elliptic Curve Digital Signature Algorithm used to sign transactions.
Blockchain Developer Fundamentals and Cryptography 3
What is a nonce in the context of proof-of-work mining?