GASP - Graph Aware Sync Protocol

GASP (Graph Aware Sync Protocol) is a protocol designed to synchronize transaction data between two parties in a blockchain environment. It ensures the legitimacy and completeness of transaction data using a recursive reconciliation method.

Features

• Synchronizes transaction data between two parties.
• Ensures legitimacy and completeness of transaction data.
• Recursive reconciliation method.
• Adaptable to various blockchain environments.
• Emphasizes security, efficiency, and data integrity.

Installation

To install the GASP library, run:

npm i @bsv/gasp

Usage

Example Usage

For now, check out the GASP test suite to see how GASP works.

The below code is for reference only, and will probably not work (it is untested). Check back later for links to examples where GASP is implemented.

Here's a basic example demonstrating how to use the GASP library:

import { GASP, GASPStorage, GASPRemote, GASPInitialRequest, GASPNode } from '@bsv/gasp';

// Mock implementation of the storage interface for demonstration purposes
class ExampleGASPStorage implements GASPStorage {
  private utxos: Array<{ txid: string; outputIndex: number; rawTx: string; timestamp?: number }> = [];

  constructor(utxos: Array<{ txid: string; outputIndex: number; rawTx: string; timestamp?: number }>) {
    this.utxos = utxos;
  }

  async findKnownUTXOs(since: number): Promise<Array<{ txid: string; outputIndex: number }>> {
    return this.utxos
      .filter(utxo => utxo.timestamp && utxo.timestamp > since)
      .map(utxo => ({ txid: utxo.txid, outputIndex: utxo.outputIndex }));
  }

  async hydrateGASPNode(graphID: string, txid: string, outputIndex: number, metadata: boolean): Promise<GASPNode> {
    const found = this.utxos.find(utxo => utxo.txid === txid && utxo.outputIndex === outputIndex);
    if (!found) {
      throw new Error('UTXO not found');
    }
    return {
      graphID,
      rawTx: found.rawTx,
      outputIndex: found.outputIndex,
      // In a real implementation, you would return real proofs and metadata
      proof: metadata ? 'example_proof' : undefined,
      txMetadata: metadata ? 'example_tx_metadata' : undefined,
      outputMetadata: metadata ? 'example_output_metadata' : undefined,
    };
  }

  async findNeededInputs(tx: GASPNode): Promise<{ requestedInputs: Record<string, { metadata: boolean }> } | void> {
    // In a real scenario, this method would analyze the transaction inputs and determine if more information is needed
    return; // Assuming no additional inputs are needed for simplicity
  }

  async appendToGraph(tx: GASPNode, spentBy?: string): Promise<void> {
    console.log(`Appending transaction to graph: ${tx.txid} at output index ${tx.outputIndex}`);
  }

  async validateGraphAnchor(graphID: string): Promise<void> {
    console.log(`Validating graph anchor for graph ID: ${graphID}`);
  }

  async discardGraph(graphID: string): Promise<void> {
    console.log(`Discarding graph with ID: ${graphID}`);
  }

  async finalizeGraph(graphID: string): Promise<void> {
    console.log(`Finalizing graph with ID: ${graphID}`);
  }
}

// Example implementation of the remote interface
class ExampleGASPRemote implements GASPRemote {
  private remoteStorage: ExampleGASPStorage;

  constructor(remoteStorage: ExampleGASPStorage) {
    this.remoteStorage = remoteStorage;
  }

  async getInitialResponse(request: GASPInitialRequest): Promise<{ UTXOList: Array<{ txid: string; outputIndex: number }> }> {
    return { UTXOList: await this.remoteStorage.findKnownUTXOs(request.since) };
  }

  async requestNode(graphID: string, txid: string, outputIndex: number, metadata: boolean): Promise<GASPNode> {
    return this.remoteStorage.hydrateGASPNode(graphID, txid, outputIndex, metadata);
  }
}

// Initializing storages and remotes for two participants: Alice and Bob
const aliceStorage = new ExampleGASPStorage([
  { txid: 'tx1', outputIndex: 0, rawTx: '010000...', timestamp: 162005 },
  { txid: 'tx2', outputIndex: 1, rawTx: '020000...', timestamp: 162010 }
]);

const bobStorage = new ExampleGASPStorage([]);

const bobRemote = new ExampleGASPRemote(aliceStorage);
const alice = new GASP(aliceStorage, bobRemote);

// Simulate synchronization process
(async () => {
  try {
    await alice.sync();
    console.log('Synchronization between Alice and Bob completed successfully.');
  } catch (error) {
    console.error('Failed to synchronize:', error);
  }
})()

License

The license for the code in this repository is the Open BSV License.