Two-Factor Authentication

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.

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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 PHP, follow our instructions to set up a PHP development environment.

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Create the PHLO

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

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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-php-demo.git<

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

$ cd 2fa-php-demo<

• Install the necessary dependencies using the composer.json file.

$ composer install<

• Edit config.ini. 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).

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A review of the code

Let‘s walk through what the code does.

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Step 1: Generate the OTP

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

   $code = random_int(100000, 999999);

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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.

function send_verification_code_phlo($dst_number,$mode)
    {
        $code = random_int(100000, 999999);
        $client = new PhloRestClient($this->config['auth_id'], $this->config['auth_token']);
        try {
            $phlo = $client->phlo->get($this->config['phlo_id']);
            $phlo->run(["from" => $this->config['app_number'], "to" => $dst_number, "mode"=>$mode, "otp"=>$code]); // These are the fields entered in the PHLO console
            return $code;
        } 
        catch (PlivoRestException $ex) {
            print_r($ex);
        }
    }

​

Step 3: Verify the OTP

We verify the OTP the user enters on their handset.

<?php
/**
 * Initiate Validation process
 * @param $param[2] route param(Phone number) from index.php
 * @param $param[3] route param(OTP entered by user) from index.php
 */
    $number = $param[2];
    $code   = $param[3];

$original_code = $client->get('number:' . $number . ':code');

​

Test

To test the application, start the Redis server.

$ redis-server<

Run the application.

$ php -S localhost:8000

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.

Here’s how to implement 2FA using Plivo APIs.

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 using Plivo APIs, follow our instructions to set up a PHP development environment.

Set up the demo application locally

• Clone the repository from GitHub

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

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

$ cd 2fa-php-demo<

• Install the dependencies using the composer.json file.

$ composer install<

• Edit config.ini. Replace the auth placeholders with your authentication credentials from the Plivo console. Replace the phone number placeholder with an actual phone number in E.164 format (for example, +12025551234). Replace the PHLO ID with null.

A review of the code

Let‘s walk through what the code does.

Step 1: Generate the OTP

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

    $code = random_int(100000, 999999);

Step 2: Send an SMS message with the OTP

Send an SMS message with the OTP to the user’s registered mobile number using Plivo’s Send Message API.

function send_verification_code_sms($dst_number, $message)
    {
        $code = random_int(100000, 999999);
        try{
            $this->$client->messages->create(["src"=>$this->config['app_number'], "dst"=>[$dst_number], "text"=>str_replace("__code__", $code, $message)]);
            return $code;

        }
        catch (PlivoRestException $ex) {
            print_r($ex);
        }
        
    }

Failover: Make a phone call with the OTP

If the SMS message doesn’t reach the mobile device, the user can request a voice OTP.

function send_verification_code_call($dst_number)
    {
        $code = random_int(100000, 999999);
        try 
        {
            $this->$client->calls->create($this->config['app_number'], [$dst_number], 'https://twofa-answerurl.herokuapp.com/answer_url/'.$code,'POST');
            return $code;
        }
        catch (PlivoRestException $ex) {
            print_r($ex);
        }
    }

Step 3: Verify the OTP

Verify the OTP the user entered on their handset.

    <?php
    /**
    * Initiate Validation process
    * @param $param[2] route param(Phone number) from index.php
    * @param $param[3] route param(OTP entered by user) from index.php
    */
        $number = $param[2];
        $code   = $param[3];

    $original_code = $client->get('number:' . $number . ':code');

Test

To test the application, start the Redis server.

$ redis-server<

Save your code and run it.

$ php -S localhost:8000

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.