ts-sdk

Script Templates

Standard and custom Bitcoin script patterns available in the BSV TypeScript SDK.

What are Script Templates?

Script templates provide reusable patterns for Bitcoin transaction locking and unlocking scripts:

import { P2PKH } from '@bsv/sdk'

// Use a standard template
const template = new P2PKH()

// Create locking script
const lockingScript = template.lock(publicKeyHash)

// Create unlocking script
const unlockingScript = template.unlock(privateKey, signature)

Standard Templates

P2PKH (Pay to Public Key Hash)

The most common Bitcoin script pattern:

const p2pkh = new P2PKH()
const lock = p2pkh.lock(publicKeyHash)
const unlock = p2pkh.unlock(privateKey, signature)

P2PK (Pay to Public Key)

Direct payment to a public key:

const p2pk = new P2PK()
const lock = p2pk.lock(publicKey)
const unlock = p2pk.unlock(signature)

OP_RETURN (Data Storage)

Store arbitrary data on-chain:

const opReturn = new OpReturn()
const lock = opReturn.lock(data)
// No unlock needed - unspendable output

Custom Templates

Create your own script templates:

class TimeLockTemplate implements ScriptTemplate {
  lock(lockTime: number, publicKeyHash: string): Script {
    return new Script()
      .writeNumber(lockTime)
      .writeOpCode(OpCode.OP_CHECKLOCKTIMEVERIFY)
      .writeOpCode(OpCode.OP_DROP)
      .writeOpCode(OpCode.OP_DUP)
      .writeOpCode(OpCode.OP_HASH160)
      .writeBin(publicKeyHash)
      .writeOpCode(OpCode.OP_EQUALVERIFY)
      .writeOpCode(OpCode.OP_CHECKSIG)
  }

  unlock(signature: string, publicKey: string): Script {
    return new Script()
      .writeBin(signature)
      .writeBin(publicKey)
  }
}

Template Interface

All templates implement the ScriptTemplate interface:

interface ScriptTemplate {
  lock(...args: any[]): Script
  unlock(...args: any[]): Script
  estimateLength?(args: any[]): number
}

Benefits

Reusability

• Standard patterns for common use cases
• Consistent implementation across applications
• Reduced development time

Security

• Well-tested script patterns
• Reduced risk of script errors
• Best practice implementations

Maintainability

• Clear separation of script logic
• Easy to update and modify
• Testable components

Working with Templates

Transaction Integration

// Use template in transaction
const output = {
  satoshis: 1000,
  lockingScript: template.lock(publicKeyHash)
}

const input = {
  sourceTransaction: prevTx,
  sourceOutputIndex: 0,
  unlockingScript: template.unlock(privateKey, signature)
}

Fee Estimation

// Estimate script size for fee calculation
const estimatedSize = template.estimateLength([publicKeyHash])
const fee = estimatedSize * feePerByte

Advanced Patterns

Multi-Signature

class MultiSigTemplate implements ScriptTemplate {
  lock(threshold: number, publicKeys: string[]): Script {
    // Implementation for m-of-n multisig
  }
  
  unlock(signatures: string[]): Script {
    // Implementation for signature collection
  }
}

Conditional Scripts

class ConditionalTemplate implements ScriptTemplate {
  lock(condition: Script, trueScript: Script, falseScript: Script): Script {
    // Implementation for IF/ELSE logic
  }
}

Best Practices

• Use standard templates when possible
• Test custom templates thoroughly
• Document template parameters clearly
• Consider script size and complexity
• Validate inputs before script creation

Next Steps

• Learn about Digital Signatures for script authorization
• Understand Transaction Structure integration
• Explore Key Management for script security

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