🔒 SecureChat

A real-time encrypted chat application built with MERN + Socket.IO to ensure secure communication using AES encryption and a custom substitution cipher for double-layered security.

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🚀 Features

✅ End-to-End Encryption using AES + Custom Cipher Algorithm 🔐
✅ Real-time Communication via Socket.IO ⚡
✅ Secure Authentication for Sender & Receiver 🔑
✅ Decryption of Messages for secure readability 🛡️

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🛠 Tech Stack

📌 Frontend: React (Vite), TailwindCSS
📌 Backend: Node.js, Express, Socket.IO
📌 Security: AES Encryption, Custom Cipher Algorithm
📌 Deployment: Render (Backend), Vercel (Frontend)

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⚙️ How It Works (Simple Workflow)

1️⃣ Key Generation

• The server generates an encryption key for Custom Cipher encryption.
• This key is structured as:
  • Chars Array → Example: ABCD
  • Key Array → Example: PORS
• Before sending, the key is AES encrypted also and then shared with both users.

2️⃣ User 1 (Sender) - Sending a Message

• The sender types a message → Encrypted using the custom cipher.
• Example: "HELLO" converts into a scrambled form like </t:0.
• This result is then AES encrypted, turning into something like "U2F2n+Jv03ay".
• The AES-encrypted message is sent to the Socket.IO server.

3️⃣ Role of Server

• The server decrypts only the AES encryption but does not revert the cipher changes.
• At this point, the message appears as suppose </t:0 (which is not yet the original message).
• The server re-encrypts the message using AES and broadcasts it to User 2 (Receiver).

4️⃣ User 2 (Receiver) - Receiving & Decryption

• The receiver gets the AES-encrypted and ciphered message.
• First, AES decryption is applied to get </t:0 from "U2F2n+Jv03ay".
• Then, custom cipher decryption restores the original message → "HELLO".