Cryptography and Hashing Flashcards

What property of a cryptographic hash function ensures that even a tiny change in input produces a completely different hash output?

Answer: Avalanche effect

The avalanche effect means a single-bit change in input dramatically alters the output hash, preventing partial-match attacks.

Which elliptic curve does Bitcoin use for its public-key cryptography?

Answer: secp256k1

Bitcoin uses the secp256k1 elliptic curve, defined over a 256-bit prime field, to generate key pairs.

What is a 'Merkle root' in the context of a Bitcoin block?

Answer: A single hash summarizing all transactions in a block

The Merkle root is a single hash derived by repeatedly hashing pairs of transaction hashes until one root hash remains.

In asymmetric cryptography, which key is used to encrypt data intended for a specific recipient?

Answer: The recipient's public key

Data is encrypted with the recipient's public key, and only the recipient's matching private key can decrypt it.

What does 'SHA' stand for in the context of Bitcoin's SHA-256 algorithm?

Answer: Secure Hash Algorithm

SHA stands for Secure Hash Algorithm, a family of cryptographic hash functions published by NIST.

Which attack attempts to find two different inputs that produce the same hash output?

Answer: Collision attack

A collision attack seeks two distinct messages M1 ≠ M2 such that hash(M1) = hash(M2).

What is the output size of SHA-256 in bits?

Answer: 256 bits

SHA-256 always produces a fixed 256-bit (32-byte) digest regardless of input size.