LogoLogo
LogoLogo
  • Intro
    • Welcome
    • The Benefits of BSV Blockchain
    • What Can I Do?
    • Overview of GitHub repositories
    • Quick Start
  • Protocol
    • Introduction
    • BSV Blockchain
      • Blocks
      • Transactions
      • Proof of Work
      • Capabilities
      • Economic Model of Governance
      • Digital Asset Recovery
    • Network Policies
      • High-Level Architecture
      • Mining
      • Standard and Local Policies
      • Consensus Rules
      • Local Policies
    • Node Operations
      • Node Software
      • Bitcoin Server Network (BSN)
      • ChainTracker
      • Transaction Validation
      • UTXO Storage
      • Mempool
      • Block Assembler
      • Block Validation
      • Mining Software
      • Pruning transactions
      • Responsibilities of a Node
    • SPV Wallets, Overlays and SPV Processes
      • Simplified Payment Verification (SPV)
      • Instant Payments
      • Integrity Checks
      • SPV Wallets & Overlays
    • Transaction Lifecycle
      • Transaction Inputs and Outputs
      • Script
      • Transaction Flow
      • Constructing a transaction
      • Sequence Number and Time Locking
      • Transaction Templates
      • Transaction Processing
      • Opcodes used in Script
    • Privacy
      • Keys and Identity
      • Private vs Anonymous
      • Digital Signatures
      • Privacy on the Public Blockchain
  • Network Access Rules
    • Rules
      • Table of Contents
      • Background to the Rules
      • PART I - MASTER RULES
      • PART II - GENERAL RULES
      • PART III - ENFORCEMENT RULES
      • PART IV - DISPUTE RESOLUTION RULES
      • PART V - INTERPRETIVE RULES
    • FAQs
      • Miners
      • Professionals
      • Users
  • Important Concepts
    • High Level
      • Web3
      • Timestamping
      • SPV
      • UTXO vs Account Based
      • Linked Keys
      • Smart Contracts
    • Details
      • Hash Functions
      • Merkle Trees
      • Sighash Flags
      • Script
      • SPV
        • Deep Dive
        • Payments Flow
        • Data Models
        • Broadcasting
  • Network Topology
    • Mandala Upgrade
    • Nodes
      • SV Node
        • Architecture
        • System Requirements
        • Installation
          • SV Node
            • Configuration
            • AWS Volumes Setup
            • DDOS Mitigation
            • Docker
            • Genesis Settings
            • GetMiningCandidate
            • GKE
            • Network Environments
              • Regtest
              • STN
              • Testnet
        • Alert System
          • Alert Messages
          • Running the Alert System
            • Startup Script
          • Webhooks
        • RPC Interface
          • RPC Methods
        • Frequently Asked Questions
          • Blocks
          • Initial Block Download
          • Transactions
          • Log File Warnings
          • Safe Mode
          • Bug Bounty
        • Chronicle Release
      • Teranode
    • Overlay Services
      • Overlay Example
    • SPV Wallet
      • Quickstart
      • Key Concepts
      • AWS Deployment
        • Installation
        • Manage & Maintain
        • Update
        • Delete
      • Components
        • SPV Wallet Server
        • Storage
        • Web Admin
        • Block Headers Service
        • Web App & API
      • Who is it for?
      • Functionality & Roadmap
      • Contribute
      • Developers Guide
        • SPV Wallet
          • Authentication
          • Configuration
          • Notification
        • Go Client
          • Authentication
        • JS Client
          • Authentication
        • Admin
        • Keygen
        • Block Headers Service
          • Authentication
          • Configuration
      • Additional Components
  • paymail
    • Overview
    • BRFC Specifications
      • Specification Documents
      • BRFC ID Assignment
    • Service Discovery
      • Host Discovery
      • Capability Discovery
    • Public Key Infrastructure
    • Payment Addressing
      • Basic Address Resolution
      • Sender Validation
      • Receiver Approvals
      • PayTo Protocol Prefix
    • Verify Public Key Owner
    • Recommendations
  • Guides
    • Local Blockchain Stack
      • Mockchain Stack
    • Business Use Cases
      • Creating a Tranche of Event Tickets
    • SDKs
      • Concepts
        • BEEF
        • Fees
        • SPV
        • Transactions
        • Op Codes
        • Script Templates
        • Signatures
        • Verification
      • TypeScript
        • Node, CommonJS
        • React
        • Low Level
          • Verification
          • ECDH
          • Numbers & Points
          • Signatures
          • 42
          • ECDSA
          • Hmacs
          • Keys
          • Scripts
        • Examples
          • Creating a Simple Transaction
          • Verifying a BEEF Structure
          • Creating Transactions with Inputs, Outputs and Templates
          • Creating the R-puzzle Script Template
          • Message Encryption and Decryption
          • Message Signing
          • Building a Custom Transaction Broadcast Client
          • Verifying Spends with Script Intrepreter
          • BIP32 Key Derivation with HD Wallets
          • Using Type 42 Key Derivation for Bitcoin Wallet Management
          • Creating a Custom Transaction Fee Model
          • Building a Pulse Block Headers Client
          • Using ECIES Encryption
      • Go
        • Examples
          • Simple Tx
          • Keys
          • Encryption
          • Broadcasting
          • Inscribing
          • Data Markers
          • Linked Keys
          • ECIES
          • Fees
          • HD Keys
          • Headers
          • Secure Messages
          • Merkle Path Verification
      • Python
        • Examples
          • Simple Tx
          • Verifying BEEF
          • Complex Tx
          • Script Templates
          • Encryption
          • Message Signing
          • Building A Custom Broadcaster
          • HD Wallets
          • Linked Keys
          • Fees
          • Merkle Path Verification
          • ECIES
  • BSV Academy
    • Getting Started
    • BSV Basics: Protocol and Design
      • Introduction
        • Bit-Coin
      • The BSV Ledger
        • The Ledger
        • Triple Entry Accounting
        • Example
      • Coins and Transactions
        • Coins
        • Transactions
        • Transaction Fees
      • Theory
      • Conclusion
    • BSV Enterprise
      • Introduction
      • About BSV Blockchain
        • Introduction
        • Safe, Instant Transactions at a Predictably Low Cost
          • Reliably Low Fees
          • Comparison to Legacy Transaction Systems
          • Payment Channels
        • Scalability to Accommodate Global Demand
          • Big Blocks Show Big Potential
        • A Plan for Regulatory Acceptance
          • Ready-made Compliance
          • The Open BSV License
        • Protocol Stability
          • Building Foundations on a Bedrock of Stone
      • Technical Details
        • The Network
          • The Small World Network
          • Robust In Its Unstructured Simplicity
        • The Bitcoin SV Node Client
          • Teranode - The Future of BSV
        • The Protocol - Simple, Robust and Unbounded
          • What is the BSV Protocol?
        • Proof of Work
          • The Algorithm
          • Efficiency of Proof of Work
        • Privacy and Identity
        • Permissions and Privacy
      • Resources and Tools
        • The Technical Standards Comittee
          • TSC Principles
          • Standard Development Process
          • Status of Current and In-progress Standards
        • The Working Blockchain
          • Pruning to Create a Working Blockchain
          • Building a Working Blockchain from a List of Block Headers
          • A World View Backed by Proof of Work
    • Hash Functions
      • What are Hash Functions?
        • The Differences Between Hashing and Encryption
        • The Three Important Properties of Hash Functions
        • The Hash Functions Found in BSV
      • Base58 and Base58Check
        • What is Base58 and Why Does Bitcoin use it?
        • What is Base58 and How Does BSV use it?
      • SHA256
        • BSV Transactions and SHA-256
        • BSV Blocks and SHA-256
        • Proof-of-Work and HASH-256
      • Walkthrough Implementation of SHA-256 in Golang
        • Overview of SHA-256
        • SHA-256 Input and Processing
        • SHA-256 Compression
        • SHA-256 Final Value Construction and Output
      • RIPEMD-160
        • BSV Addresses & WIFs
      • Walkthrough Implementation of RIPEMD-160 in Golang
        • Overview of RIPEMD-160
        • RIPEMD-160 Input and Processing
        • RIPEMD-160 Compression
        • RIPEMD-160 Final Value Construction and Output
      • Doubla Hashing and BSV's Security
        • Why is Double Hashing Used in BSV
        • Hash Functions and BSV's Security Model
    • Merkle Trees
      • The Merkle Tree
        • What is a Merkle Tree?
        • Why use a Merkle Tree?
        • Merkle Trees in Action
      • Merkles Trees in BSV
        • The Data Elements
        • Transaction Merkle Trees
        • Transaction Merkle Trees in Action
      • Merkle Trees and the Block Header
        • What is the Block Header
        • The Hash Puzzle
        • Proof-of-Work in Action
      • Merkle trees and Verifying Proof of Work
        • Broadcasting the Block
        • The Coinbase Transaction
        • Data Integrity of the Block
        • Saving Disk Space
      • Standarised Merkle Proof
        • What is a Merkle Proof?
        • The BSV Unified Merkle Path (BUMP) Standard
        • Simple and Composite Proofs
      • Merkle Trees and Simplified Payment Verification
        • SPV
        • Offline Payments
    • Digital Signatures
      • What are Digital Signatures
        • Background
        • Introduction
        • Digital Signatures Protocol
        • Properties of Digital Signatures
      • ECDSA Prerequisites
        • Disclaimer
        • Modular Arithmetic
        • Groups, Rings and Finite Fields
        • Discrete Logarithm Problem
        • Elliptic Curve Cryptography (ECC)
        • Discrete Logarithm Problem with Elliptic Curves
      • ECDSA
        • Introduction
        • ECDSA
        • Further Discussion
      • BSV and Digital Signatures
        • Introduction
        • BSV Transaction
        • ECDSA (secp256k1) for BSV Transaction
        • Summary
        • Signed Messages
        • Miner Identification and Digital Signatures
    • BSV Theory
      • Abstract
        • Peer-to-Peer Cash
        • Digital Signatures and Trusted Third Parties
        • Peer-to-Peer Network
        • Timechain and Proof-of-Work
        • CPU Power
        • Cooperation in the Network
        • Network Structure
        • Messaging Between Nodes
      • Introduction
        • Commerce on the Internet
        • Non Reversible Transactions
        • Privacy in Commerce
        • The Paradigm of Fraud Acceptance
        • What is Needed...
        • Protecting Sellers From Fraud
        • Proposed Solution
        • Security and Honesty
      • Transactions
        • Electronic Coins
        • Spending a Coin
        • Payee Verification
        • Existing Solutions
        • First Seen Rule
        • Broadcasting Transactions
        • Achieving Consensus
        • Proof of Acceptance
      • Timestamp Server
        • Timestamped Hashes
        • A Chain of Timestamped Hashes
      • Proof of Work
        • Hashcash
        • Scanning Random Space
        • Nonce
        • Immutable Work
        • Chain Effort
        • One CPU, One Vote
        • The Majority Decision
        • The Honest Chain
        • Attacking the Longest Chain
        • Controlling the Block Discovery Rate
      • Network
        • Running the Network
        • The Longest Chain
        • Simultaneous Blocks
        • Breaking the Tie
        • Missed Messages
      • Incentive
        • The Coinbase Transaction
        • Coin Distribution
        • Mining Analogy
        • Transaction Fees
        • The End of Inflation
        • Encouraging Honesty
        • The Attacker's Dilemma
      • Reclaiming Disk Space
        • Spent Transactions
        • The Merkle Tree
        • Compacting Blocks
        • Block Headers
      • Simplified Payment Verification
        • Full Network Nodes
        • Merkle Branches
        • Transaction Acceptance
        • Verification During Attack Situations
        • Maintaining an Attack
        • Invalid Block Relay System
        • Businesses Running Nodes
      • Combining and Splitting Value
        • Dynamically Sized Coins
        • Inputs and Outputs
        • A Typical Example
        • Fan Out
      • Privacy
        • Traditional Models
        • Privacy in Bitcoin
        • Public Records
        • Stock Exchange Comparison
        • Key Re-Use
        • Privacy - Assessment 2
        • Linking Inputs
        • Linking the Owner
      • Calculations
        • Attacking the Chain
        • Things the Attacker Cannot Achieve
        • The Only Thing an Attacker Can Achieve
        • The Binomial Random Walk
        • The Gambler's Ruin
        • Exponential Odds
        • Waiting For Confirmation
        • Attack Via Proof of Work
        • Vanishing Probabilities
      • Conclusion
        • Conclusion Explained
    • Introduction to Bitcoin Script
      • Chapter 1: About Bitcoin Script
        • 01 - Introduction
        • 02 - FORTH: A Precursor to Bitcoin Script
        • 03 - From FORTH to Bitcoin Script
        • 04 - Bitcoin's Transaction Protocol
        • 05 - Transaction Breakdown
        • 06 - nLockTime
        • 07 - The Script Evaluator
      • Chapter 2: Basic Script Syntax
        • 01 - Introduction
        • 02 - Rules Around Data and Scripting Grammar
        • 03 - The Stacks
      • Chapter 3: The Opcodes
        • 01 - Introduction
        • 02 - Constant Value and PUSHDATA Opcodes
        • 03 - IF Loops
        • 04 - OP_NOP, OP_VERIFY and its Derivatives
        • 05 - OP_RETURN
        • 06 - Stack Operations
        • 07 - Data transformation
        • 08 - Stack Data Queries
        • 09 - Bitwise transformations and Arithmetic
        • 10 - Cryptographic Functions
        • 11 - Disabled and Removed Opcodes
      • Chapter 4: Simple Scripts
        • 01 - Introduction
        • 01 - Pay to Public Key (P2PK)
        • 02 - Pay to Hash Puzzle
        • 03 - Pay to Public Key Hash (P2PKH)
        • 04 - Pay to MultiSig (P2MS)
        • 05 - Pay to MultiSignature Hash (P2MSH)
        • 06 - R-Puzzles
      • Chapter 5: OP_PUSH_TX
        • 01 - Turing Machines
        • 02 - Elliptic Curve Signatures in Bitcoin
        • 03 - OP_PUSH_TX
        • 04 - Signing and Checking the Pre-Image
        • 05 - nVersion
        • 06 - hashPrevouts
        • 07 - hashSequence
        • 08 - Outpoint
        • 09 - scriptLen and scriptPubKey
        • 10 - value
        • 11 - nSequence
        • 12 - hashOutputs
        • 13 - nLocktime
        • 14 - SIGHASH flags
      • Chapter 6: Conclusion
        • Conclusion
    • BSV Infrastructure
      • The Instructions
        • The Whitepaper
        • Steps to Run the Network
        • Step 1
        • Step 2
        • Step 3
        • Step 4
        • Step 5
        • Step 6
      • Rules and their Enforcement
        • Introduction
        • Consensus Rules
        • Block Consensus Rules
        • Transaction Consensus Rules
        • Script Language Rules
        • Standard Local Policies
      • Transactions, Payment Channels and Mempools
      • Block Assembly
      • The Small World Network
        • The Decentralisation of Power
        • Incentive Driven Behaviour
        • Lightspeed Propagation of Transactions
        • Ensuring Rapid Receipt and Propagation of New Blocks
        • Hardware Developments to Meet User Demand
        • Novel Service Delivery Methods
        • MinerID
      • Conclusion
  • Research and Development
    • BRCs
    • Technical Standards
  • Support & Contribution
    • Join Our Discord
    • GitHub
Powered by GitBook
On this page
  • Block Headers and Merkle Proofs
  • Simplified Payment Verification (SPV)
  • Block Headers Client
  • Verifying a BEEF Structure

Was this helpful?

Edit on GitHub
Export as PDF
  1. Guides
  2. SDKs
  3. TypeScript
  4. Examples

Verifying a BEEF Structure

PreviousCreating a Simple TransactionNextCreating Transactions with Inputs, Outputs and Templates

Last updated 1 year ago

Was this helpful?

The BSV SDK comes with advanced capabilities around the SPV architecture. In Bitcoin, SPV refers to the process of creating, exchanging, and verifying transactions in a way that anchors them to the blockchain. One of the standard formats for representing the necessary SPV data is known as BEEF (background-evaluated extended format), representing a transaction and its parents together with needed merkle proofs. This example will show you how to verify the legitimacy of a BEEF-formatted SPV structure you've received, checking to ensure the target transaction and its ancestors are well-anchored to the blockchain based on the current chain of block headers. First we'll unpack these concepts, then we'll dive into the code.

Block Headers and Merkle Proofs

In Bitcoin, miners create blocks. These blocks comprise merkle trees of the included transactions. The root of the merkle tree, together with other useful information, is collected together into a block header that can be used to verify the block's proof-of-work. This merkle tree structure enables anyone to keep track of the chain of block headers without keeping a copy of every Bitcoin transaction.

Merkle proofs are simply a way for someone to prove the existence of a given transaction within a given merkle tree, and by extension, its inclusion by the miners in a particular block of the blockchain. This becomes extremely important and useful when we think about Simplified Payment Verification (SPV).

Simplified Payment Verification (SPV)

The process for SPV is detailed in , but the main idea is that when a sender sends a transaction, they include merkle proofs on all of the input transactions. This allows anyone with a copy of the Bitcoin block headers to check that the input transactions are included in the blockchain. Verifiers then check that all the input and output scripts correctly transfer value from one party to the next, ensuring an unbroken chain of spends. The provides a compact and efficient way for people to represent the data required to perform SPV.

Block Headers Client

To verify BEEF structures with the BSV SDK, you'll need to provide a block headers client that, given a merkle root, will indicate to the library whether the merkle root is correct for the block that's in the active chain at the given block height.

For simplicity in this example, we are going to use a mock headers client that always indicates every merkle root as valid no matter what. However, in any real project, you MUST always use an actual block headers client or attackers will be able to easily fool you with fraudulent transactions!

The TypeScript BSV SDK does not ship with a block headers client, but check out this example (link to be provided once complete) for setting up Pulse.

Here is the gullible block headers client we will be using:

const gullibleHeadersClient = {
    // DO NOT USE IN A REAL PROJECT due to security risks of accepting any merkle root as valid without verification
    isValidRootForHeight: async (merkleRoot, height) => {
      console.log({ merkleRoot, height })
      return true
    }
}

Verifying a BEEF Structure

Now that you have access to a block headers client (either Pulse on a real project or the above code for a toy example), we can proceed to verifying the BEEF structure with the following code:

import { Transaction } from '@bsv/sdk'

// Replace with the BEEF structure you'd like to check
const BEEFHex = '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'

// You can create a Transaction from BEEF hex directly
const tx = Transaction.fromHexBEEF(BEEFHex)

// This ensures the BEEF structure is legitimate
const verified = await tx.verify(gullibleHeadersClient)

// Print the results
console.log(verified)

The above code allows you to ensure that a given BEEF structure is valid according to the rules of SPV.

BRC-67
BEEF data structure