Two-Factor Authentication Using Ruby

You can create and deploy a PHLO to handle 2FA with a few clicks on the PHLO canvas and trigger it with a few lines of code.

Prerequisites

To get started, you need a Plivo account — sign up with your work email address if you don’t have one already. If this is your first time triggering a PHLO with Ruby, follow our instructions to set up a Ruby development environment.

Create the PHLO

Plivo provides a prototype for 2FA; all you have to do is select the PHLO and give it a friendly name.

Set up the demo application locally

Once you‘ve created the PHLO, download and modify the code to trigger it.

• Clone the repository from GitHub.

 $ git clone https://github.com/plivo/2fa-ruby-demo.git

• Change your working directory to 2fa-ruby-demo.

 $ cd 2fa-ruby-demo

• Install the necessary dependencies using the Gemfile.

 $ bundle install

• Edit config.yaml. Replace the auth placeholders with your authentication credentials from the Plivo console. Enter your PHLO ID, which you can find on the Plivo console. Replace the phone number placeholder with an actual phone number in E.164 format (for example, +12025551234).

A review of the code

Let‘s walk through what the code does.

Step 1: Generate the OTP

We use the Time-Based OTP algorithm to generate a random six-digit one-time password (OTP).

1
code = rand(999_999)

Step 2: Send SMS and make a call

With a single function, we can send an SMS message or make a call via PHLO (in the event the initial SMS message never arrives). The argument that tells PHLO whether to send an SMS message or make a call is mode, and the allowed values passed to it are sms and call.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
def initiate_phlo(dst_number, mode)
    code = rand(999_999)
    begin
      phlo = @phloclient.phlo.get(@phlo_id)
      # parameters set in PHLO - params
      params = {
        from: @app_number,
        to: dst_number,
        otp: code,
        mode: mode
      }
      phlo.run(params)
      code
    rescue PlivoRESTError => e
      puts 'Exception: ' + e.message
    end
  end

Step 3: Verify the OTP

We verify the OTP the user enters on their handset.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
get '/checkcode/:number/:code' do
  ##
  # Validates the code entered by the user
  #
  number = params['number']
  code = params['code']
  original_code = r.get('number:%s:code' % number)
  content_type :json
  if original_code == code
    r.del('number:%s:code' % number)  # verification successful, delete the code
    return { status: 'success', message: 'codes match, number verified' }.to_json
  elsif original_code != code
    return { status: 'failure', message: 'codes do not match, number not verified' }.to_json
  else
    return { status: 'rejected', message: 'number not found' }.to_json
end

Test

To test the application, start the Redis server.

 $ redis-server

Run the application.

$ ruby app.rb

Set up ngrok to expose your local server to the internet.

You should be able to see the application in action at https://<ngrok_identifier>.ngrok.io/.

The finished application should look like this.