Quiz 2: Blockchain and Crypto

Hash Function

A function that maps input data of any size to a fixed-size output.

Collision Resistance

A property of a hash function where it is infeasible to find two different inputs that produce the same hash.

Pre-Image Resistance

Given a hash output

Puzzle-Friendliness

A property ensuring that it is hard to find an input that hashes to a specific target output.

Birthday Paradox

A probability principle that shows how likely it is for two values to hash to the same output.

Message Digest

The fixed-size output of a hash function.

HMAC (Hash-Based Message Authentication Code)

A MAC constructed using a cryptographic hash function and a secret key.

SHA-256

A cryptographically secure hash function used in Bitcoin and many other security applications.

Brute-Force Attack

A method of breaking security by trying all possible inputs until the correct one is found.

Hash Pointer

A pointer to data along with a cryptographic hash of that data

Tamper-Evident Log

A system where modifications to data are easily detectable.

Merkle Tree

A binary tree where each node contains the hash of its children

One-Way Function

A function that is easy to compute but difficult to reverse.

Nonce

A random or unique number used only once in cryptographic computations.

Commitment Scheme

A method of "locking" a value before revealing it later

Digital Signature

A cryptographic technique that ensures message authenticity and integrity.

Non-Repudiation

A security property where the sender cannot deny having sent a message.

Public-Key Cryptography

A system where encryption and decryption use different keys.

Private Key

A secret key used to sign messages and decrypt encrypted data.

Public Key

A key shared publicly to verify signatures or encrypt messages.

RSA Algorithm

A widely used asymmetric encryption algorithm.

ECDSA (Elliptic Curve Digital Signature Algorithm)

A digital signature scheme used in Bitcoin for verifying transactions.

Key Pair

A set of public and private keys used in asymmetric encryption.

Existential Unforgeability

A security property where an attacker cannot generate a valid signature for a new message.

Certificate Authority (CA)

An entity that verifies public keys and issues digital certificates.

Symmetric Encryption

An encryption method where the same key is used for both encryption and decryption.

Asymmetric Encryption

An encryption method where different keys are used for encryption and decryption.

AES (Advanced Encryption Standard)

A widely used symmetric encryption algorithm.

MAC (Message Authentication Code)

A cryptographic checksum ensuring integrity and authenticity.

Ciphertext

The scrambled version of plaintext after encryption.

Plaintext

The original message

Key Exchange

The process of securely exchanging cryptographic keys between parties.

Digital Certificate

A signed electronic document verifying the identity of a public key holder.

Salt

A random value added to passwords before hashing to prevent dictionary attacks.

Hybrid Encryption

A combination of symmetric and asymmetric encryption techniques.

GoofyCoin

A fictional cryptocurrency where Goofy creates and controls coins.

Double-Spending

A problem where the same digital currency is spent more than once.

Transaction Signing

A process where a user signs a transaction with their private key.

ScroogeCoin

A centralized cryptocurrency where all transactions are verified by Scrooge.

Immutable Ledger

A record that cannot be changed once written.

Blockchain History

The full set of transactions stored in a blockchain.

Coin Creation in GoofyCoin

Coins are created and signed by Goofy.

Coin Consumption in ScroogeCoin

Coins must be signed and included in Scrooge’s blockchain to be valid.

Splitting Coins in ScroogeCoin

Coins can be split into multiple smaller coins via transactions.

Centralized Authority

A single entity controls the system (e.g.

Blockchain

A chain of blocks linked together by cryptographic hashes.

Genesis Block

The first block in a blockchain.

Block

A collection of transactions stored together in a blockchain.

Block Hash

A cryptographic hash of a block’s contents.

Merkle Root

The top hash in a Merkle tree representing all transactions in a block.

Mining

The process of solving cryptographic puzzles to add new blocks to a blockchain.

Proof-of-Work

A consensus algorithm requiring computational work to validate transactions.

Consensus Mechanism

The method by which nodes agree on the blockchain state.

Decentralization

The absence of a single controlling entity in a system.

Immutable Data

Data that cannot be altered after being recorded.

51% Attack

When a single entity gains majority control over a blockchain network.

Fork

A split in a blockchain where nodes follow different sets of rules.

Private Blockchain

A blockchain with restricted access.

Public Blockchain

A blockchain that anyone can participate in and validate transactions.

Smart Contract

Self-executing code stored on a blockchain.

Gas Fee

A fee paid for executing transactions or smart contracts.

Ethereum

A blockchain known for its smart contract functionality.

Bitcoin

The first decentralized cryptocurrency.

Altcoin

Any cryptocurrency other than Bitcoin.

Lightning Network

A layer 2 solution for faster Bitcoin transactions.

Replay Attack

Reusing valid data transmission to gain unauthorized access.

Man-in-the-Middle Attack

An attacker intercepts and alters communication between two parties.

Brute-Force Attack

Trying all possible keys or passwords to break encryption.

Dictionary Attack

Using a precomputed list of passwords to crack a system.

Side-Channel Attack

Exploiting physical signals from a system to break encryption.

Key Length

The size of a cryptographic key (e.g.

Entropy

A measure of randomness in cryptographic security.

Zero-Knowledge Proof

A method to prove knowledge of a secret without revealing it.

Homomorphic Encryption

Allows computations on encrypted data without decrypting it.

Nonce Reuse

A security flaw that can compromise cryptographic systems.

Hash Chain

A sequence of hashes where each depends on the previous one.

Distributed Ledger

A database replicated across multiple nodes.

Node

A participant in a blockchain network.

Validator

A node that verifies transactions and adds them to the blockchain.

Cryptographic Salt

Random data added to inputs before hashing.

Mining Difficulty

The measure of how hard it is to find a valid block hash.

Digital Wallet

Software for storing private keys for cryptocurrencies.

Hot Wallet

A cryptocurrency wallet connected to the internet.

Cold Wallet

An offline cryptocurrency wallet for security.

Block Reward

The incentive given to miners for adding new blocks.

Decentralized Finance (DeFi)

Financial services built on blockchain networks.

Sybil Attack

An attack where a single entity creates multiple fake identities.

Tokenization

Converting real-world assets into digital tokens.

Cross-Chain Transactions

Transactions that occur between different blockchains.