Cryptographic Principles Flashcards
7 cards from real Blockchain Technology practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Cryptographic Principles flashcards as text
What is a 'hash pointer' in the context of blockchain data structures?
Answer: A data structure containing both a cryptographic hash of the previous block's data and a link to that block
A hash pointer stores the cryptographic hash of the previous block's content alongside its location, ensuring any tampering with past data invalidates subsequent hashes.
Which attack exploits weak random number generation during ECDSA signing, potentially exposing a private key?
Answer: Nonce reuse attack (k-value reuse)
If the same nonce k is used in two different ECDSA signatures, an attacker can algebraically recover the private key from the two signatures.
What does 'pre-image resistance' mean for a cryptographic hash function used in blockchain?
Answer: Given a hash output, it is computationally infeasible to find any input that produces it
Pre-image resistance ensures that knowing the hash output provides no practical way to reconstruct an input that would hash to that value.
In zk-SNARKs used by privacy blockchains like Zcash, what does 'succinct' mean?
Answer: The proof size and verification time are small and constant regardless of computation size
Succinct means the proof is very short and verification is fast (often milliseconds), even if the underlying computation being proved is large.
Which cryptographic concept underpins the security of blockchain Proof-of-Work by making it easy to verify but hard to compute?
Answer: Computational asymmetry (one-way functions)
One-way functions are easy to evaluate but practically impossible to invert, so finding a valid nonce requires enormous work while verifying it takes a single hash computation.
What is the purpose of BIP-39 mnemonic seed phrases in blockchain wallets from a cryptographic standpoint?
Answer: They encode a random entropy value as human-readable words, which deterministically derive wallet keys via PBKDF2
BIP-39 converts a random entropy value into a word list and uses PBKDF2-HMAC-SHA512 with the words as input to derive a master seed for HD wallet key generation.
In a Merkle Patricia Trie (used in Ethereum's state), what cryptographic guarantee does the root hash provide?
Answer: It commits to the entire state so any modification to any account changes the root hash
The Merkle Patricia Trie root hash is a cryptographic commitment to the full state; altering any account balance or contract storage changes the root, making tampering detectable.