opensig-ts

Javascript e-signature library for digitally signing and verifying files on EVM-based blockchains using the OpenSig standard. See also https://opensig.net/about.

Also supports public and private message notarisation to the blockchain.

Usage

OpenSig notarises signatures on the blockchain via the OpenSig Registry smart contract. Registries are available on most major blockchains - see https://opensig.net/about#contracts for their addresses. To inform us of new public registries please contact [email protected].

Node.js / React

Installation

npm install opensig-ts

Usage

import { OpenSig, RegistryContract, EthersProvider, SignatureData } from 'opensig-ts';
import { ethers } from 'ethers';

const privateKey = ethers.randomBytes(32);
const chainId = 137;

const registryContract: RegistryContract = {
  address: "0x4037E81D79aD0E917De012dE009ff41c740BB453",
  creationBlock: 40031474
};

// Construct an OpenSig blockchain provider (see Blockchain Providers section below)

const signer = new ethers.Wallet(
  privateKey, 
  new ethers.JsonRpcProvider("https://polygon-rpc.com")  // provider used for publishing signatures
);

const signatureProvider = new EthersProvider(
  chainId,
  registryContract, 
  signer, 
  new ethers.JsonRpcProvider("https://polygon-rpc.com")  // provider used for querying signatures
);

// Construct an OpenSig instance that uses your provider

const opensig = new OpenSig(signatureProvider);

// Construct an OpenSig Document object from a File (or from a document hash)

const myDoc = new opensig.createDocument(new File('./myfile.txt'));

// Verify signatures on the blockchain

const signatures = await myDoc.verify();

signatures.forEach(sig => console.log(sig.time, sig.signatory, sig.data));

// Sign a document. 
// NB: You must `verify()` a document at least once before signing. This brings the object's
// signature chain up to date with the blockchain. See https://opensig.net/about for 
// information about how and why OpenSig chains signatures.

const signData: SignatureData = {
  type: 'string',
  encrypted: true,
  content: 'some data'
};

const result = await myDoc.sign(signData);

console.log(result.txHash, result.signatory, result.signature);

const receipt = await result.confirmed;

console.log('signature published successfully', receipt);

Signature Data

Signatures are published with an optional annotation. Annotations can be strings, objects or binary. By default annotations are encrypted using the document hash (H_d) as the encryption key. This ensures only those with the original document can decrypt the annotation.

Example annotations:

const noData: SignatureData = { type: 'none' };

const unencryptedStringData: SignatureData = {
  type: 'string',
  encrypted: false,
  content: "Hello World!"
}

const encryptedBinaryData: SignatureData = {
  type: 'binary',
  encrypted: true,
  content: "0x010203040506" // binary in hex form
}

const encryptedObjectData: SignatureData = {
  type: 'object',
  encrypted: true,
  content: { foo: 'bar', baz: [1, 2, 3] }
}

Note:

• String data is unicode.
• Object data is packed with the MessagePack protocol.

Blockchain Providers

OpenSig blockchain providers publish signature transactions to the blockchain and query the blockchain for signature events.

The bundled EthersProvider should be sufficient for most purposes, however you are free to implement your own. See src/providers for the IBlockchainProvider interface.

EthersProvider

An EthersProvider publishes and verifies signatures using ethers built in Provider instances.

This allows OpenSig to be used with browser-installed wallets, RPC providers and community providers like Ankr and Infura (see ethers community providers).

The EthersProvider class takes separate signer and rpcProvider constructor parameter. The signer must have a provider

AbstractEVMProvider

Extend AbstractEVMProvider to verify signatures using an ethers provider and publish via a custom protocol.

Testing

This project uses Jest for unit test.

npm test

Contributing

Contributions are welcome. To submit a pull request:

1. Fork the repository

2. Create a new branch (git checkout -b feature/my-feature)

3. Make your changes and add tests if needed

4. Run the test suite with npm test

5. Submit a pull request

Please keep your changes focused and well-documented. Thanks for helping improve the project!

Support

If you'd like to report a bug or suggest a feature then please open an issue in the Github repository.

For usage or any other support please contact [email protected].

License

MIT License (including all dependencies)