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OTP JWT ⎆

One time password (email, SMS) authentication support for HTTP APIs.

The man who wrote the book on password management has a confession to make: He blew it.

— WSJ.com

This project provides a couple of mixins to help you build applications/HTTP APIs without asking your users to provide passwords.

Your browser probably can work seamlessly with OTPs!!! 😍

About

The goal of this project is to provide support for one time passwords which are delivered via different channels (email, SMS), along with a simple and easy to use JWT authentication.

Main goals:

  • No magic please
  • No DSLs please
  • Less code, less maintenance
  • Good docs and test coverage
  • Keep it up-to-date (or at least tell people this is no longer maintained)

The available features include:

  • Flexible models support for counter based OTP
  • Flexible JWT token generation helpers for models and arbitrary data
  • Pluggable authentication flow using the OTP and JWT
  • Pluggable OTP mailer
  • Pluggable OTP SMS background processing job

This little project wouldn't be possible without the previous work on ROTP and JWT.

Thanks to everyone who worked on these amazing projects!

Sponsors

I'm grateful for the following companies for supporting this project!

Installation

Add this line to your application's Gemfile:

gem 'otp-jwt'

And then execute:

$ bundle

Or install it yourself as:

$ gem install otp-jwt

Usage

To start using it with Rails, add this to an initializer and configure your keys:

# config/initializers/otp-jwt.rb
require 'otp'
# To load the JWT related support.
require 'otp/jwt'

# Set to 'none' to disable verification at all.
# OTP::JWT::Token.jwt_algorithm = 'HS256'

# How long the token will be valid.
# OTP::JWT::Token.jwt_lifetime = 60 * 60 * 24

OTP::JWT::Token.jwt_signature_key = ENV['YOUR-SIGN-KEY']

OTP for Active Record models

To add support for OTP to your models, use the OTP::ActiveRecord concern:

class User < ActiveRecord::Base
  include OTP::ActiveRecord

  ...
end

This will provide two new methods which you can use to generate and verify one time passwords:

  • User#otp
  • User#verify_otp

This concern expects two attributes to be provided by the model, the:

  • otp_secret: of type string, used to store the OTP signature key
  • otp_counter: of type integer, used to store the OTP counter
  • expire_jwt_at: of type datetime, optional and used to force a token to expire

A migration to add these two looks like this:

$ rails g migration add_otp_to_users otp_secret:string otp_counter:integer

Generate opt_secret by running the following in rails console if you have preexisting user data:

User.all.each do |u|
  u.save()
end
Force a token to expire

If there's an expire_jwt_at value that is in the past, the user token will be reset and it will require a new authentication to receive a working token.

This is handy if the user access needs to be scheduled and/or removed.

Mailer support

You can use the built-in mailer to deliver the OTP, just require it and overwrite the helper method:

require 'otp/mailer'

class User < ActiveRecord::Base
  include OTP::ActiveRecord

  def email_otp
    OTP::Mailer.otp(email, otp, self).deliver_later
  end
end

To customize the mailer subject, address and template, update the defaults:

require 'otp/mailer'

OTP::Mailer.default subject: 'Your App magic password 🗝️'
OTP::Mailer.default from: ENV['DEFAUL_MAILER_FROM']
# Tell mailer to use the template from app/views/otp/mailer/otp.html.erb
OTP::Mailer.prepend_view_path(Rails.root.join('app', 'views'))

SMS delivery support

You can use the built-in job to deliver the OTP via SMS, just require it and overwrite the helper method:

require 'otp/sms_otp_job'

class User < ActiveRecord::Base
  include OTP::ActiveRecord

  SMS_TEMPLATE = '%{otp} is your APP magic password 🗝️'

  def sms_otp
    OTP::SMSOTPJob.perform_later(
      phone_number,
      otp,
      SMS_TEMPLATE # <-- Optional text message template.
    ) if phone_number.present?
  end
end

You will have to provide your model with the phone number attribute if you want to deliver the OTPs via SMS.

This job requires aws-sdk-sns gem to work. You will have to add it manually and configure to use the correct keys. The SNS region is fetched from the environment variable AWS_SMS_REGION.

JWT for Active Record models

To add support for JWT to your models, use the OTP::JWT::ActiveRecord concern:

class User < ActiveRecord::Base
  include OTP::JWT::ActiveRecord

  ...
end

This will provide two new methods which you can use to generate and verify JWT tokens:

  • User#from_jwt
  • User#to_jwt

JWT authorization

To add support for JWT to your controllers, use the OTP::JWT::ActionController concern:

class ApplicationController < ActionController::Base
  include OTP::JWT::ActionController

  private

  def current_user
    @jwt_user ||= User.from_jwt(request_authorization_header)
  end

  def current_user!
    current_user || raise('User authentication failed')
  rescue
    head(:unauthorized)
  end
end

The example from above includes helpers you can use interact with the currently authenticated user or just use as part of before_action callback.

The request_authorization_header method is also provided by the concern and allows you to customize from where the token is received. A query parameter based alternative would look like this:

class ApplicationController < ActionController::Base
  include OTP::JWT::ActionController

  private

  def current_user
    @jwt_user ||= User.from_jwt(params[:token])
  end

  ...
end

JWT authentication

The OTP::JWT::ActionController concern provides support for handling the authentication requests and token generation by using the jwt_from_otp method.

Here's an example of a tokens controller:

class TokensController < ApplicationController
  def create
    user = User.find_by(email: params[:email])

    jwt_from_otp(user, params[:otp]) do |auth_user|
      # Let's update the last login date before we send the token...
      # auth_user.update_column(:last_login_at, DateTime.current)

      render json: { token: auth_user.to_jwt }, status: :created
    end
  end
end

The jwt_from_otp does a couple of things here:

  • It will try to authenticate the user you found by email and respond with a valid JWT token
  • It will try to schedule an email or SMS delivery of the OTP and it will respond with the 400 HTTP status
  • It will respond with the 403 HTTP status if there's no user or the OTP is wrong

The OTP delivery is handled by the User#deliver_otp method and can be customized. By default it will call the sms_otp method and if nothing is returned, it will proceed with the email_otp method.

JWT Tokens

To help sign any sort of data, a lightweight JWT Token wrapper is provided.

Signing a payload will follow the pre-defined settings like the lifetime and the encryption key. Decoding a token will validate any claims as well. Finally there's a safe wrapper to help you with the JWT specific exceptions handling.

require 'otp/jwt/token'

token = OTP::JWT::Token.sign(sub: 'my subject')
OTP::JWT::Token.decode(token) == {'sub' => 'my subject'}
OTP::JWT::Token.decode('bad token') == nil

Development

After checking out the repo, run bundle to install dependencies.

Then, run rake to run the tests.

To install this gem onto your local machine, run bundle exec rake install.

To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/stas/otp-jwt

This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.