lecture 10

A digital ledger of transactions that are organized into blocks chained together. Blocks are cryptographically linked to prevent tampering.

A unit of data in a blockchain that holds a group of transactions.

An action recorded on a blockchain, like a financial exchange.

Securely coding information within blocks to prevent unauthorized access.

The agreement among all nodes in a blockchain network on the validity of a new block.

A database that is replicated across multiple computers (nodes) in a network.

The process of adding new blocks to the blockchain.

A cryptographic method to verify the authenticity and integrity of a transaction.

A mathematical function that takes input data and produces a fixed-length, unique output called a hash. This output is designed to be highly sensitive to any changes in the input data.

A specific type of hash function widely used in blockchain. It produces a hash value that is always 256 bits (0s and 1s) long, regardless of the input data.

A unit of data in a blockchain containing various information, including transactions, timestamps, and a hash value. Each block links to the previous block in the chain, creating a secure record of all transactions.

The first block in a blockchain, which acts as the foundation for the entire chain. It often contains specific information like the initial setup of the blockchain.

A sequence of hash values where each block's hash is linked to the previous block's hash. This chain ensures the integrity and immutability of the blockchain.

By using hashing, any changes made to a block will result in a different hash value. This change will disrupt the hash chain, making it impossible to tamper with past transactions without detection.

The 'prev' field inside a block refers to the hash value of the preceding block. It acts as a link connecting current block to its ancestor, ensuring the chain's integrity.

Blockchain resembles a singly linked list, where each block has a pointer to the previous block's hash. However, the hash calculation itself can be considered a bidirectional relationship.

Individuals participate in a blockchain to earn transaction fees and block rewards. Transaction fees are paid by users for their transactions to be included in a block, while block rewards are given to miners who successfully create and add a block to the blockchain.

Mining refers to the process of finding a valid nonce (a random number) that satisfies a specific hash threshold for a block. This involves computationally intensive computations and is a race among miners to find the valid nonce first.

Once a miner finds a valid nonce, they create a block with their transactions and broadcast it to the network. Other miners validate the block, and if it's accepted by a majority, it is added to the chain. The miner who added the valid block receives the transaction fees and block reward.

Proof-of-Work ensures security by requiring miners to invest significant computational power to find valid nonces. This makes it difficult and costly to cheat the system by adding invalid blocks, as it would require a large amount of resources to overcome the majority mining power.

The hash threshold defines the difficulty of mining a new block by setting a target hash value. Miners must find a nonce that produces a hash lower than or equal to this threshold. A higher threshold means more difficult mining but also more secure blockchain.

The block reward decreases over time in Bitcoin. Initially, every block created received a fixed amount of Bitcoin. However, this reward reduces by half after a certain number of blocks are mined. This halving event ensures that the total number of Bitcoin will remain limited.

Proof-of-Work makes the blockchain expansion slower as it takes significant time and computation for miners to find valid nonces. This slower expansion can make the blockchain less responsive to rapid changes, but it also strengthens security.

The security of a blockchain relies on the concept of proof-of-work. This implies that attackers face a high cost to compromise the system. They would need to control a majority of the mining power, which is extremely difficult and expensive. This makes it secure and tamper-proof.

Blockchain is not ideal for general data storage. Limitations include slow transaction speed, high cost, and difficulty in efficiently handling data updates.

A situation where multiple miners create new blocks in a blockchain simultaneously, resulting in two or more competing chains.

The rule that determines the final state of a blockchain by selecting the longest chain, resolving conflicts arising from forks.

Blockchain's ability to track physical objects is limited due to the potential for manipulation in the real world.

Blockchain is suitable for applications requiring secure, transparent, and tamper-proof record-keeping, such as international payments, anti-counterfeiting, and data provenance.

Blockchain achieves agreement on the present by establishing a shared history, ensuring trust among participants through a distributed and tamper-proof system.

The foundation of blockchain is a chain of blocks linked by cryptographic hashes, guaranteeing the integrity and immutability of the recorded information.

The shared understanding and trust created through the agreement on historical data in a blockchain leads to consensus on the present.