Hello guys! πŸ‘‹

Today, let's discover a small chat application developed with React Hooks, Firebase and a new package named Seald! πŸ”₯

cybersecurity meme
Created with meme-studio.io

End-to-end encryption can be complex and expensive to redevelop, even if it is essential to protect the confidential data your applications handle. With Seald SDK, we perform end-to-end encryption on data stored, produced or received by your applications.

Let's take an example with a chat application! πŸ’ͺ

Structure of our chat app 🧰

Seald chat demo
React + Firebase + Seald

Above is a demo of our chat app in React, with an end-to-end encryption system, including several features:

🟒 Create a room
🟒 Add/Remove users from a room
🟒 Modify a room
🟒 Registration / Login
🟒 User status
🟒 Encrypting and decrypting a message

The main tools used are:

Firebase, a ready-to-use framework which allows us to create a persistent authentication system, save our encrypted messages in a database and receive them instantly when a user posts a new message.

React which will be our frontend library to perform and design simple views for each state in our application.

Seald, the turnkey library we will use to bring end-2-end encryption πŸ” to the chat.

Auth system πŸ‘¨β€πŸ’»

React Router
Router with 3 routes

Only 3 routes for our chat application with authentication. Registration, login and room management.

We define if the routes are allowed for authenticated users or not.

Password derivation πŸ”

Normally, we would send Firebase the password in cleartext, and then Firebase would derive it with a secure function such as SCRYPT in order to avoid having it in the database.

In our case, we want to prevent Firebase from ever being able to read the password, even if it’s not stored, because we’re going to use it for protecting the Seald identity end-2-end (even from Firebase).

In order to do that, we just do the same operation Firebase does, but before giving it to Firebase : we derive the password with a secure function (SCRYPT) and then use it as a password.

Password derivation
Password derivation before giving it to Firebase

Sign up πŸ‘€

In order to create a user in this application, a simple form containing 3 fields is enough:

Sign up Seald demo
Sign up form
Sign up code
Sign up code

Nothing very complicated in the code. We ask Firebase to create an authentication via an email and a password provided by the user.

And also add some informations about the user, like the name and a photo URL.

Then, we add the Seald application layer to create our future
encrypted messages.

Sign in πŸ‘€

Then, the login. A classic form (email / password) in order to access the rooms and be able to chat with other users.

Sign in Seald demo
Sign in form
Sign in Seald code
Sign in code

Same as on the registration. We retrieve the Firebase authentication of the user and his Seald account.

Rooms πŸ‘¨β€πŸ‘©β€πŸ‘¦β€πŸ‘¦

That's where the interesting part comes from.

On this application, it is possible to chat in 1 to 1 with an another user, but also to chat with a group of users in a custom room.

Create a room 🧸

Add room Seald demo
Create a room
Add room Seald code
Code for adding a room

Let's detail this code together:

  • First, we send the form data to Firebase. The name of the room and the selected users are required.
  • Then we create an encrypted session using the Seald SDK. This will allow to encrypt and decrypt a message for this room.
  • And finally, we want to send the first encrypted message to welcome the users of this room.
Demo hello
Our first room!

Send encrypted messages πŸ”

Now, let's chat! But, remember, we want an End-To-End encryption for the messages.

Seald sdk

Before each created message, we need to check if we have an authenticated Seald session. If not, create that session with the SDK πŸ”’.

Then, the session allows us to encrypt a string, which is our message.

Alice πŸ‘© sends a message to Bob πŸ‘¨

"Hello my friend"

We call the method encrypt for our message above:

Seald encrypt message

The message will become:

Encrypted message Seald
πŸ”΄ Before decrypting messages

Now, Bob πŸ‘¨(and other users of the room) need to decrypt the message of Alice πŸ‘©. How can we do that?

Decrypted messages πŸ”

Seald sdk code decrypt

Now that we know how to send an encrypted message, let's see how to retrieve a message instantly and decrypt it for other users.

We use the value event to read our messages, as they existed at the time of the event. This method is triggered once when the listener is attached and again every time the data, including children, changes.

Read more about reading and writing Data with Firebase πŸ“‚

We retrieve our message list every time a message is added. So, an encrypted message is displayed, but now we need to be able to decrypt it:

Bob πŸ‘¨ actually sees:


We call the method decrypt for our encrypted message above:

Decrypt sdk Seald

Bob πŸ‘¨ will now see:

"Hello my friend"
Chat demo decrypted Seald
🟒 After decrypting messages

We now have a real-time chat with an end-to-end encryption system πŸ’ͺ

Note: To use the Seald SDK, go to seald.io.


Cheers, 🍻 🍻 🍻