Study Guide for Blockchain Interaction Scripts

Study Guide for Blockchain Interaction Scripts

Short Answer Questions

Please explain what a "smart contract" is in blockchain technology? How does it differ from a traditional contract?

A smart contract is a computer program designed to automatically execute the terms of a machine-readable contract or agreement. Unlike traditional contracts that can be described in natural language, it is automatically executed and self-enforced on the blockchain.

What role does ECDSA play in blockchains, such as Bitcoin?

ECDSA (Elliptic Curve Digital Signature Algorithm) is used in blockchains to generate digital signatures to ensure that only the legitimate owner of a digital asset can transfer the asset. For example, in Bitcoin, ECDSA is used to sign transactions to verify that the sender has the corresponding private key.

Please explain the concepts of "Lock Script" and "Unlock Script" and the relationship between them.

The lock script, also known as the release condition, specifies the conditions that need to be met to transfer the UTXO, such as requiring specific data to be provided. The unlock script is used to provide data that satisfies the lock script conditions, thereby "unlocking" the digital asset.

Why is it problematic to embed the hash value of data directly in the lock script in some cases?

When generating a locking script, if the required data is not yet determined (e.g., unknown or not fixed), its hash cannot be pre-embedded.

Please explain what the O P _ C H E C K B L O C K V E R I F Y script does and explain how it works.

This script is used to verify that the provided data is a valid block header. It does this by checking that the length of the data is 80 bytes, the "nBits" field is greater than or equal to the blockchain mining difficulty, and the SHA256 hash value is lower than the target value.

How to verify that the provided block header is the block header of the previous block?

By checking that the hash value of the first block header is equal to the "HashPrevBlock" field of the second block, it can be verified that the first block header is the previous block header of the second block.

What role does the "Merkle Root" play in verifying the state of the blockchain?

The Merkle root is the root hash value of the hash values ​​of all transactions in the block, recorded in the block header. By comparing the Merkle branch of the provided transaction with the Merkle root of the block header, it is possible to verify that the transaction was included in the block.

Explain how blockchain state can be used to enhance the security of smart contracts.

By embedding verification of blockchain state in smart contracts, such as requiring the provision of specific block headers or verifying the existence of transactions, malicious behavior can be prevented and the contract can be ensured to execute according to preset conditions.

Please describe how the feature of "Automatic Execution" is implemented in smart contracts.

Automatic execution refers to the fact that any entity can effectively unlock the UTXO without proving its identity (for example, possession of a private key). This can be achieved by setting conditions in the locking script that can be met without verifying identity.

How is "Self-Enforcement" implemented in smart contracts?

Self-enforcement is achieved in two ways: first, restrictions are imposed on the continuous set of unlocking transaction fields and reflected in the unlocking transaction; second, the blockchain network enforces the restrictions in the locking script.

Paper Title

Discuss the advantages and limitations of using scripting languages ​​in blockchain technology.

Analyze how blockchain state can be used in smart contracts to implement more complex logic and functions.

Evaluate the security and efficiency of different types of blockchain state verification methods.

Explore the potential and challenges of script-based blockchain interactions in decentralized finance (DeFi) applications.

Design and describe a decentralized application case that uses blockchain state verification to enhance security.

Glossary

Blockchain: A distributed database consisting of multiple blocks that are linked in chronological order. Each block contains a set of transaction records and is linked to the previous block through cryptography.

Smart Contract: A self-executing contract stored on a blockchain whose terms are written in code and automatically executed when preset conditions are met.

Lock Script: A script code stored in a UTXO that specifies the conditions that need to be met to spend the UTXO.

Unlock Script: A script code included in a transaction that is used to provide data that satisfies the conditions of the lock script, thereby unlocking the corresponding UTXO.

UTXO (Unspent Transaction Output): Unspent transaction output refers to the output of a transaction that has not been spent and can be used as input for the next transaction.

ECDSA (Elliptic Curve Digital Signature Algorithm): Elliptic Curve Digital Signature Algorithm, an algorithm for generating and verifying digital signatures, commonly used for signing blockchain transactions.

Block Header: A part of each block in the blockchain that contains key information about the block, such as version number, timestamp, hash value of the previous block, Merkle root, etc.

Merkle Root: The root hash value of the hash values ​​of all transactions in the block, used to verify the integrity of transactions in the block.

Blockchain State: The overall situation of the blockchain at a specific point in time, including all confirmed transactions, account balances, smart contract status, etc.

Automatic Execution: A feature of smart contracts, which means that the contract is automatically executed when the preset conditions are met without human intervention.

Self-Enforcement: Another feature of smart contracts, which means that the execution of the contract is enforced by the blockchain network itself, and no participant can violate the contract rules.