JavaScript Encrypted Data Vault Client (edv-client)

A JavaScript library for Web and node.js apps for interfacing with a remote Encrypted Data Vault server

Table of Contents

• Background
• Install
• Usage
• API
• Contribute
• Commercial Support
• License

Background

This library provides a client that Web and node.js apps can use to interface with remote Encrypted Data Vault (EDV) servers.

It consists of one main class:

1. EdvClient - instances provide a CRUD (+ find) interface to a specific configured Encrypted Data Vault server and ensure appropriate database indexes are set up. Static methods allow for the creation of EDVs with a remote storage service, e.g. Encrypted Data Vault storage server.

Install

• Browsers and Node.js 18+ are supported.
• Streams API required. Older browsers must use a polyfill.
• Web Crypto API required. Older browsers must use a polyfill.

To install from NPM:

npm install @digitalbazaar/edv-client

To install locally (for development):

git clone https://github.com/digitalbazaar/edv-client.git
cd edv-client
npm install

Usage

Creating and registering an Encrypted Data Vault (EDV)

First, create a key agreement key and an HMAC (hash-based message authentication code) key for encrypting your documents and blinding any indexed attributes in them. This requires creating some cryptographic key material which can be done locally or via a KMS system. The current example shows using a KMS system (TODO: show a simpler local example):

import {CapabilityAgent, KeystoreAgent, KmsClient} from 'webkms-client';
import {EdvClient} from 'edv-client';

Although Encrypted Data Vaults are not bound to any particular key management system, we recommend that you set up a Key Management Service using an implementation such as webkms-switch which you can connect to using webkms-client.

Optional:

// create a CapabilityAgent (for invoking zcaps)
const capabilityAgent = await CapabilityAgent.fromSecret({secret, handle});

// create a keystore and an agent for working with it
// the baseUrl can be set to a dev API or production API
const kmsBaseUrl = `${config.server.baseUri}/kms`;
const keystore = KmsClient.createKeystore({
  // the url for the keystore is configurable
  url: `${kmsBaseUrl}/keystores`,
  config: {
    // on init the sequence must be 0
    sequence: 0,
    controller: capabilityAgent.id,
    invoker: capabilityAgent.id,
    // this allows the capabilityAgent to delegate zCaps
    delegator: capabilityAgent.id
  },
  /**
   * optional `httpsAgent`,
   * usually not applicable for front-end (you may use axios),
   * for back-end use cases a nodejs `https.Agent`
   * may be used to allow the use of self signed certificates using
   * the `rejectUnauthorized: false` flag in the contructor.
  */
  httpsAgent
});
const keystoreAgent = new KeystoreAgent({keystore, capabilityAgent});

// use the keystore agent to create key agreement and HMAC keys
const keyAgreementKey = await keystoreAgent.generateKey({type: 'keyAgreement'});
const hmac = await keystoreAgent.generateKey({type: 'hmac'});

Now you can create and register a new EDV configuration:

// TODO: explain EDV service must be able to authenticate user
const controller = 'account id goes here';

const config = {
  // on init the sequence must be 0 and is required
  sequence: 0,
  controller,
  // TODO: Explain what 'referenceId' is
  referenceId: 'primary',
  keyAgreementKey: {id: keyAgreementKey.id, type: keyAgreementKey.type},
  hmac: {id: hmac.id, type: hmac.type}
};

// sends a POST request to the remote service to create an EDV
const remoteConfig = await EdvClient.createEdv({config});

// connect to the new EDV via a `EdvClient`
const client = new EdvClient({id: remoteConfig.id, keyAgreementKey, hmac});
// to only use fips-compliant key agreement and encryption algorithms:
const client = new EdvClient(
  {id: remoteConfig.id, keyAgreementKey, hmac, cipherVersion: 'fips'});

You can specify a url when you create and register a new EDV configuration:

// TODO: explain EDV service must be able to authenticate user
const controller = 'account id (or DID if using zcaps) goes here';

const config = {
  // on init the sequence must be 0 and is required
  sequence: 0,
  controller,
  // TODO: Explain what 'referenceId' is
  referenceId: 'primary',
  keyAgreementKey: {id: keyAgreementKey.id, type: keyAgreementKey.type},
  hmac: {id: hmac.id, type: hmac.type}
};

// sends a POST request to the remote service to create an EDV
const remoteConfig = await EdvClient.createEdv({
  url: 'https://server.example/edvs',
  config,
  // must pass `invocationSigner` and optional `capability` if `controller`
  // is a DID
  /* invocationSigner, capability */
});

// connect to the new EDV via a `EdvClient`
const client = new EdvClient({id: remoteConfig.id, keyAgreementKey, hmac});

Loading a saved EDV config

If you have previously registered an EDV config (via createEdv()), and you know its id, you can fetch its config via get():

// registered config
const {id} = await EdvClient.createEdv({config});

// later, it can be fetched via the id
const remoteConfig = await EdvClient.getConfig({id});

// connect to the existing EDV via an `EdvClient` instance
const client = new EdvClient({id: remoteConfig.id, keyAgreementKey, hmac});

If you know a controller/accountId but do not know a specific EDV id, you can create a client for an EDV by a controller-scoped custom referenceId:

// get the account's 'primary' EDV config to connect to the EDV
// note that a referenceId can be any string but must be unique per controller
const config = await EdvClient.findConfig(
  {controller: accountId, referenceId: 'primary'});
const client = new EdvClient({id: config.id, keyAgreementKey, hmac});

Using a EdvClient instance for document storage

See the API section below.

API

EdvClient

constructor

insert

get

update

delete

find

ensureIndex

updateIndex

Contribute

Please follow the existing code style.

PRs accepted.

If editing the Readme, please conform to the standard-readme specification.

Commercial Support

Commercial support for this library is available upon request from Digital Bazaar: [email protected]

License

BSD-3-Clause © Digital Bazaar