Cryptography and Hashing Flashcards
7 cards from real Cryptocurrency practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Cryptography and Hashing flashcards as text
What is the 'birthday attack' vulnerability in hashing, and why does it matter for blockchain?
Answer: A statistical attack finding hash collisions faster than brute force due to probability theory
The birthday paradox shows collisions can be found in roughly 2^(n/2) attempts rather than 2^n, so 256-bit hashes provide ~128-bit collision security.
What is a 'commitment scheme' in cryptography as used in some blockchain protocols?
Answer: A method to commit to a value privately and reveal it verifiably later
A commitment scheme lets a party bind to a chosen value without revealing it, then later open the commitment to prove what they chose.
How does a Merkle proof allow lightweight clients (SPV nodes) to verify a transaction?
Answer: By providing a branch of hashes from the transaction to the Merkle root without sending all transactions
A Merkle proof supplies only log2(n) hashes needed to reconstruct the path to the root, enabling transaction verification without full block data.
What makes the Discrete Logarithm Problem (DLP) important for elliptic curve cryptography in blockchains?
Answer: It is computationally infeasible to derive a private key from a public key
The DLP hardness on elliptic curves means computing the private key from the public key is computationally infeasible with current technology.
What does 'deterministic' mean when describing a cryptographic hash function?
Answer: The same input always produces the same output
Determinism means identical inputs always yield identical hash outputs, which is essential for consensus across blockchain nodes.
In HD (Hierarchical Deterministic) wallets, what role does HMAC-SHA512 play?
Answer: It derives child key pairs from a parent key and a chain code
HD wallets use HMAC-SHA512 with a parent key and chain code as inputs to deterministically derive child private and public keys.
What is 'salting' in the context of password hashing for cryptocurrency wallet security?
Answer: Appending a random value to a password before hashing to prevent rainbow table attacks
A salt is a unique random value added to each password before hashing, ensuring identical passwords produce different hashes and defeating precomputed lookup tables.