Blockchain Assignment 2

Hash Function is a mathematical algorithm that takes an input of any size (such as a word, a number, or an entire file) and converts it into a fixed-size string or value. Its role in the blockchain is to help secure data, detect tampering, and link blocks together. Example, hash function converts blockchain data into a unique looking digital fingerprint that help detect tampering and link blocks securely together.

Deterministic Property means that the same input always produces the same hash output when using the same algorithm. In blockchain technology, the deterministic property ensures that the same data always produces the same hash, allowing nodes to verify transactions and blocks consistently and detect any changes to the data. For instance, If a user sends 10 coins to another user, every blockchain node applying the same hash algorithm to the exact same transaction data gets the same hash, allowing them to verify the transaction consistently.

Collision Resistance mean it is extremely difficult to find 2 different inputs that produce the same hash output. In blockchain, it help protect the integrity of transactions and blocks by making it difficult for different data to share the same hash. For example, if user send 10$ to another user and someone changes it to 100$, the 2 transactions should produce different hashes, making the change detectable.

Public Key Cryptography is a system that uses a pair of keys, a public key and a private key, to secure transactions and verify digital signatures in blockchain technology. It allows users to prove ownership of their digital assets and authorize transactions securely without sharing their private keys. Example, user uses their private key to digitally sign a transaction sending user B 10$, and the blockchain network uses her public key to verify that the signature is valid.

Private Key is a secret digital key used to sign and authorize transactions in blockchain technology. It proves control over digital assets and helps prevent unauthorized transactions. Example, Alice uses her private key to sign a transaction sending Bob 10 coins, proving that she authorized the transaction without revealing her private key.

digital signature is a cryptographic method used to verify the authenticity and integrity of a digital message or transaction. its role is to help verify the sender's authorization and detect unauthorized changes to transaction data. Example, when user A send money to user B, she sign the transaction using her private key, and the blockchain network verifies the signature using her public key before accepting the transaction.

Merkle tree is a data structure that uses cryptographic hashes to organize and verify data efficiently. In blockchain technology, a Merkle tree helps verify that transactions have not been changed and allows transactions to be checked without downloading all the data in a block. If a block contains four transactions (A, B, C, and D), their hashes are combined in pairs and hashed again until one final hash, called the Merkle root, is produced. If any transaction changes, the Merkle root changes too.

Immutability is the property of data that prevents it from being changed or deleted easily once it has been recorded. In blockchain technology, immutability helps maintain data integrity and trust because changing recorded information requires overcoming the network’s security mechanisms and consensus rules. Example Once a transaction is recorded on a blockchain, it cannot normally be altered without detection, helping prevent transaction records from being secretly modified.

Proof-of-Work (PoW) s a blockchain consensus mechanism in which miners solve computational puzzles to validate transactions and add new blocks to the blockchain. In blockchain technology, PoW helps secure the network, prevent fraud, and make it difficult for attackers to modify transaction records. Example In Bitcoin, miners use computing power to find a valid block hash. The successful miner can add the block to the blockchain and receive a reward.

Tamper Detection is the process of identifying unauthorized changes to data. In blockchain technology, tamper detection uses cryptographic hashes and links between blocks to reveal if recorded information has been modified. Example If someone changes a transaction in a blockchain, its hash changes, alerting the network that the data may have been tampered with.

51% attack occurs when an individual or group controls more than 50% of a blockchain network’s mining power in a Proof-of-Work system. In blockchain technology, this control may allow attackers to reorganize recent transactions, reverse their own payments, or prevent transactions from being confirmed. Example: An attacker controlling over 50% of Bitcoin’s mining power could attempt to reverse their own payment and spend the same coins again, known as a double-spending attack.

Double spending is an attack in which the same digital currency is spent more than once. In blockchain technology, consensus mechanisms and transaction verification help prevent the same cryptocurrency from being used in multiple transactions. Example: user A sends 1 Bitcoin to user B, then attempts to spend that same Bitcoin again with another transaction. The blockchain network must reject the conflicting transaction to prevent double spending.

Blockchain Assignment 2

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