Blockchain Fundamentals Flashcards
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Read the first 7 Blockchain Fundamentals flashcards as text
What is the primary purpose of a Merkle tree in a blockchain block?
Answer: To efficiently verify the integrity of all transactions in a block
A Merkle tree allows efficient and secure verification of transaction inclusion by hashing pairs of transactions up to a single root hash stored in the block header.
In a Proof-of-Work blockchain, what does 'difficulty adjustment' accomplish?
Answer: It modifies the target hash threshold to maintain a consistent block time
Difficulty adjustment periodically recalculates the target hash value so that the average time to find a valid block stays near the protocol's target interval (e.g., 10 minutes for Bitcoin).
Which property ensures that altering any historical block on a blockchain invalidates all subsequent blocks?
Answer: Each block contains the cryptographic hash of the previous block
Because each block header includes the prior block's hash, modifying an old block changes its hash, breaking the chain link and invalidating every block that follows.
What distinguishes a 'soft fork' from a 'hard fork' in blockchain protocol upgrades?
Answer: Soft forks are backward-compatible; hard forks are not
A soft fork tightens validation rules so old nodes still accept new blocks, whereas a hard fork introduces rules that make new blocks invalid under the old protocol, requiring all participants to upgrade.
From an audit perspective, what is the significance of an 'unspent transaction output' (UTXO)?
Answer: It is the fundamental unit of value that can be referenced as input in future transactions
UTXOs are discrete units of cryptocurrency that have been received but not yet spent; auditors verify the UTXO set to confirm ownership and prevent double-spending.
Which attack vector is specifically prevented by a blockchain's immutability once a transaction reaches sufficient confirmations?
Answer: Double-spend attack
Sufficient confirmations make reversing a transaction computationally infeasible, directly preventing a double-spend where the same coins are spent more than once.
What role does a 'genesis block' play in a blockchain?
Answer: It is the first block that establishes the chain's origin with no predecessor
The genesis block is the hard-coded first block of a blockchain, having no parent hash, and it anchors the entire chain's history.