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Hackernoon logoImplementing OAuth.0 using Google Sign-in for a DIY Secure Smart Lock by@namrathasubramanya

Implementing OAuth.0 using Google Sign-in for a DIY Secure Smart Lock

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@namrathasubramanyaNamratha Subramanya

In Part One, we built our own IoT smart lock with secure access management and learned how to implement a secure smart lock system using PubNub Access Manager (PAM). In this part, let’s implement OAuth 2.0 using Google sign-in, a secure authentication system. This reduces the burden of login for the users of your app, by enabling them to sign-in with their Google account.

A full GitHub repo for the project is available here.

What is OAuth?

OAuth is an open standard for authorization of which any developer can implement it. OAuth provides access to your personal data without exposing user’s password. OAuth 2.0 is the latest and most conventional version of OAuth. The key thing to note is that OAuth 2.0 is a completely new protocol and it is not backward compatible with the previous versions. Google APIs use the OAuth 2.0 protocol for authentication and authorization.

Getting Started

Before you can integrate Google sign-in into your app, you need to create Client ID. Client ID is a unique string representing the registration information provided by Google. You can configure your project here.

In the Authorized JavaScript origins field, enter the origin for your app. I am running this demo on Apache server and hence I have set my origin to http://localhost:8080/

You also need to include the following line into your HTML page:

<script src="https://apis.google.com/js/platform.js" async defer></script>

Go to Developers Console and click on Enable APIs and Services and search for “Google+ API”. Enable this API and copy your Client ID. This goes into the below line:

<meta name="google-signin-client_id" content="YOUR_CLIENT_ID.apps.googleusercontent.com">

You could use the following lines of code in your HTML page to create the sign-in button.

You can customize the button according to Google standard by checking this link.

Google Authentication

The first step is to initialize your client ID in JavaScript code. It can be done using the code below:

You must send the ID token to your server with an HTTPS POST request. After you receive the ID token, you must verify the integrity of the token. To validate the ID token using tokeninfo endpoint, you need to make a GET or POST request to the following:

https://www.googleapis.com/oauth2/v3/tokeninfo?id_token=XYZ123

PubNub Functions

PubNub Functions is a Function-as-a-Service platform that allows you to program the PubNub Data Stream Network. PubNub Functions enables users to quickly and easily spin up micro-services in the PubNub Data Stream Network (DSN) without the requirement of any additional supporting infrastructure. You can call these functions on request, after presence, after publish or before publish according to your convenience.

In this demo, we are going to use PubNub Functions with our login and signup functions to create new accounts, verify if the accounts exist and check their passwords so that the device can get access to operate the smart lock.

Sign Up Function

In the signup function, we check if the user already has a smart lock account. If the user doesn’t have one, we create a smart lock account by saving the user credentials into the kvstore database which can be entered by the user every time they log in.

The kvstore is a persistent key-value store that acts as a database to the PubNub Functions. You can read more about kvstore in this link.

Login Function

In the login function, we check if the user has an account and if they do, we check if the password entered is matching with the password stored in kvstore.

Google Signup

Once your PubNub Function for signup is ready, you can copy the URL and do POST request by passing the ID and password as parameters.

Google Login

Similar to signup, a POST request is done with ID and password as parameters. If the username and password exist then the webpage is directed to the screen where you can lock and unlock the smart lock.

UUID

When you instantiate a PubNub instance (i.e. new PubNub()), the PubNub SDK generates a new UUID for you. So this UUID could be used as your authKey to which you can grant access in your Python script. Different ways to generate UUID can be found in this link.

Once you set your UUID in Python script, you can subscribe to the message in your login page so that the smart lock sends UUID to your login page. After the UUID is set as authKey, PubNub Access Manager (PAM) grants access to the UUID so that your device can access the smart lock.

Wrapping Up

As you can see, OAuth and PubNub Access Manager go hand in hand to provide two layers of security to your smart lock. In order to make your Google authentication more secure, you can make sure that you do not accept plain user IDs. Instead, you can send the token that you acquired on the client side to the server. Then you can make a server-side API call using that token to get the user ID.

You can download my demo project from my Github here.

Originally published at www.pubnub.com.

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