Virgil Pythia Objective-C/Swift SDK

Introduction | SDK Features | Installation | Usage Examples | Docs | Support

Introduction

Virgil Security provides an SDK which allows you to communicate with Virgil Pythia Service and implement Pythia protocol in order to generate user's BrainKey. BrainKey is a user's Private Key which is based on user's password. BrainKey can be easily restored and is resistant to online and offline attacks.

SDK Features

• communicate with Virgil Pythia Service
• generate user's BrainKey
• use Virgil Crypto library

Installation

Virgil Pythia SDK is provided as a set of frameworks. These frameworks are distributed via SPM and CocoaPods. Also in this guide, you find one more package called VirgilCrypto (Virgil Crypto Library) that is used by the SDK to perform cryptographic operations.

Frameworks are available for:

• iOS 9.0+
• macOS 10.11+
• tvOS 9.0+
• watchOS 2.0+

COCOAPODS

CocoaPods is a dependency manager for Cocoa projects. You can install it with the following command:

$ gem install cocoapods

To integrate Virgil Pythia into your Xcode project using CocoaPods, specify it in your Podfile:

target '<Your Target Name>' do
  use_frameworks!

  pod 'VirgilSDKPythia', '~> 0.12.1'
end

Then, run the following command:

$ pod install

Swift Package Manager

Swift Package Manager is an official Apple tool for managing the distribution of Swift code.

The Apple documentation can be used to add frameworks to an Xcode project.

Usage Examples

BrainKey

PYTHIA Service can be used directly as a means to generate strong cryptographic keys based on user's password or other secret data. We call these keys the BrainKeys. Thus, when you need to restore a Private Key you use only user's Password and Pythia Service.

In order to create a user's BrainKey, go through the following operations:

• Register your E2EE application on Virgil Dashboard and get your app credentials
• Generate your API key or use available
• Set up JWT provider using previously mentioned parameters (App ID, API key, API key ID) on the Server side
• Generate JWT token with user's identity inside and transmit it to Client side (user's side)
• On Client side set up access token provider in order to specify JWT provider
• Setup BrainKey function with access token provider and pass user's password
• Send BrainKey request to Pythia Service
• Generate a strong cryptographic keypair based on a user's password or other user's secret

Generate BrainKey based on user's password

import VirgilSDK
import VirgilSDKPythia

/// 1. Specify your JWT provider

// Get generated token from server-side
let authenticatedQueryToServerSide: ((String) -> Void) -> Void = { completion in
    completion("eyJraWQiOiI3MGI0NDdlMzIxZjNhMGZkIiwidHlwIjoiSldUIiwiYWxnIjoiVkVEUzUxMiIsImN0eSI6InZpcmdpbC1qd3Q7dj0xIn0.eyJleHAiOjE1MTg2OTg5MTcsImlzcyI6InZpcmdpbC1iZTAwZTEwZTRlMWY0YmY1OGY5YjRkYzg1ZDc5Yzc3YSIsInN1YiI6ImlkZW50aXR5LUFsaWNlIiwiaWF0IjoxNTE4NjEyNTE3fQ.MFEwDQYJYIZIAWUDBAIDBQAEQP4Yo3yjmt8WWJ5mqs3Yrqc_VzG6nBtrW2KIjP-kxiIJL_7Wv0pqty7PDbDoGhkX8CJa6UOdyn3rBWRvMK7p7Ak")
}

// Setup AccessTokenProvider
let accessTokenProvider = CallbackJwtProvider { tokenContext, completion in
    authenticatedQueryToServerSide { jwtString in
        completion(jwtString, nil)
    }
}

/// 2. Setup BrainKey

let brainKeyContext = BrainKeyContext.makeContext(accessTokenProvider: accessTokenProvider)
let brainKey = BrainKey(context: brainKeyContext)

// Generate default public/private keypair which is Curve ED25519
// If you need to generate several BrainKeys for the same password,
// use different IDs (optional). Default brainKeyId value is nil.
let keyPair = try! brainKey.generateKeyPair(password: "Your password",
                                            brainKeyId: "Optional BrainKey id").startSync().getResult()

Generate BrainKey based on unique URL

The typical BrainKey implementation uses a password or concatenated answers to security questions to regenerate the user’s private key. But a unique session link generated by the system admin can also do the trick.

This typically makes the most sense for situations where it’s burdensome to require a password each time a user wants to send or receive messages, like single-session chats in a browser application.

Here’s the general flow of how BrainKey can be used to regenerate a private key based on a unique URL:

• When the user is ready to begin an encrypted messaging session, the application sends the user an SMS message
• The SMS message contains a unique link like https://healthcare.app/?session=abcdef13803488
• The string 'abcdef13803488' is used as a password for the private key regeneration
• By clicking on the link, the user immediately establishes a secure session using their existing private key regenerated with Brainkey and does not need to input an additional password

Important notes for implementation:

• The link is one-time use only. When the user clicks on the link, the original link expires and cannot be used again, and so a new link has to be created for each new chat session.
• All URL links must be short-lived (recommended lifetime is 1 minute).
• The SMS messages should be sent over a different channel than the one the user will be using for the secure chat session.
• If you’d like to add additional protection to ensure that the person clicking the link is the intended chat participant, users can be required to submit their name or any other security question. This answer will need to be built in as part of the BrainKey password.

...
    let keyPair = try! brainKey.generateKeyPair(password: "abcdef13803488",
                                                brainKeyId: "Optional User SSN").startSync().getResult()
...

Note! if you don't need to use additional parameters, like "Optional User SSN", you can just omit it: let keyPair = try! brainKey.generateKeyPair(password: "abcdef13803488").startSync().getResult()

Docs

Virgil Security has a powerful set of APIs, and the documentation below can get you started today.

• Brain Key Use Case
• The Pythia PRF Service - foundation principles of the protocol
• Virgil Security Documentation

License

This library is released under the 3-clause BSD License.

Support

Our developer support team is here to help you. Find out more information on our Help Center.

You can find us on Twitter or send us email support@VirgilSecurity.com.

Also, get extra help from our support team on Slack.