How to Implement Advanced Secure Communication using Celo's On-Chain Messaging Protocol


In today’s interconnected world, secure communication is of utmost importance. Celo, a blockchain platform, offers an on-chain messaging protocol that enables secure communication between users on the Celo network. In this tutorial, we will explore how to use Celo’s on-chain messaging protocol to build a secure messaging application. We will provide an overview of the protocol’s features, guide you through the setup and configuration process using the Celo SDK, and demonstrate how to send and receive messages securely.

Complete Code for our Tutorial


  • Before diving into the implementation details, make sure you have the following prerequisites in place:
  • Basic knowledge of blockchain technology and smart contracts.
  • Familiarity with the Celo blockchain platform.


  • Development environment set up with Node.js and npm installed.

  • Access to the Celo network either through a local development environment or a public testnet.


Step 1: Understanding Celo’s On-Chain Messaging Protocol

Before we start building our secure messaging application, let’s familiarize ourselves with Celo’s on-chain messaging protocol and its key features:

End-to-End Encryption: Celo’s messaging protocol ensures that messages are encrypted from the sender to the recipient, providing privacy and security for all communication.

Message Authentication: The protocol employs digital signatures to verify the authenticity of messages, preventing tampering and ensuring that messages originate from the expected sender.

Decentralized Infrastructure: The messaging protocol operates on the Celo blockchain, leveraging its decentralized architecture for message propagation and storage.

Step 2: Setting up the Development Environment

To begin building our secure messaging application, we need to set up our development environment. Follow these steps:

Install Node.js and npm: Download and install Node.js from the official website ( This will also install npm, the Node Package Manager.

Initialize a New Project: Open your terminal and navigate to the desired directory for your project. Run the following command to create a new project:


$ mkdir secure-messaging-app

$ cd secure-messaging-app

$ npm init -y

This will create a new directory for your project and generate a package.json file.

Install the Celo SDK: Install the Celo SDK by running the following command:

$ npm install @celo/contractkit

This will install the necessary dependencies to interact with the Celo blockchain.

Step 3: Configuring the Messaging Application

Now that our development environment is set up, we can configure our messaging application to connect to the Celo network. Follow these steps:

Import Dependencies: In your project’s main JavaScript file, import the necessary dependencies:


const Web3 = require('web3');

const ContractKit = require('@celo/contractkit');

Connect to the Celo Network: Create a connection to the Celo network using the ContractKit and Web3 libraries:


const web3 = new Web3('');

const kit = ContractKit.newKitFromWeb3(web3);

Replace the URL with the appropriate Celo network endpoint based on your desired network (e.g., mainnet, testnet).

Configure Accounts: Configure the accounts that will interact with the messaging protocol. For simplicity, we’ll use a single account in this tutorial:


const account = web3.eth.accounts.create();

const privateKey = account.privateKey;

const senderAddress = account.address;


Make sure to store the generated privateKey and senderAddress securely.

Step 4: Sending Messages

With our application configured, we can now send messages securely using Celo’s messaging protocol. Follow these steps:

Load the Messaging Contract: Load the messaging contract provided by the Celo SDK:


const messaging = await kit.contracts.getContract('Messaging');

Encrypt and Send a Message: Use the messaging contract’s sendEncryptedMessage function to encrypt and send a message to a recipient:


const recipientAddress = '<recipient-address>';

const message = 'Hello, world!';

const encryptedMessage = await messaging.encrypt(senderAddress, recipientAddress, message);

await messaging.sendEncryptedMessage(recipientAddress, encryptedMessage);

Replace with the actual Celo address of the recipient.

Step 5: Receiving Messages

To complete our secure messaging application, we need to implement the logic for receiving messages. Follow these steps:

Retrieve Incoming Messages: Use the messaging contract’s getIncoming function to retrieve the incoming encrypted messages for the current account:


const incomingMessages = await messaging.getIncoming();

Decrypt and Display Messages: Decrypt and display the received messages:


incomingMessages.forEach(async (encryptedMessage) => {

const decryptedMessage = await messaging.decrypt(senderAddress, encryptedMessage);

console.log(`Received message: ${decryptedMessage}`);



Congratulations! You’ve successfully built a secure messaging application using Celo’s on-chain messaging protocol. Throughout this tutorial, we explored the features of Celo’s messaging protocol, set up the development environment, configured the messaging application, and implemented the logic for sending and receiving messages securely. By leveraging Celo’s on-chain messaging protocol, you can ensure end-to-end encryption and message authentication for secure communication on the Celo network.

Next steps

Remember to explore the Celo documentation and SDK references for further customization and advanced features to enhance your messaging application’s security and functionality. Happy coding!

About the Author​

Chidi Anachebe is a content producer and a backend engineer skilled in Solidity, web3, Ruby, Python, and Node.js. Overall, I’m enthusiastic about the opportunities that blockchain technology presents and am committed to use my abilities to contribute to any technology I lay my hands on in a positive way.

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Celo Official Documentation: The official Celo documentation is a great place to start. It includes guides, API references, and tutorials related to Celo’s features, including its messaging protocol. You can find it at:

Celo GitHub Repository: The Celo project is open-source, and you can find the SDK, smart contracts, and related code on their GitHub repository. You might find implementation details and examples there: Celo · GitHub


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Thank you @Celo_Academy


very interesting


I will be reviewing this

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