Overview
CryptChat is a privacy-first Android chat application built with robust security features, including AES-256 symmetric encryption for real-time messaging and steganography-based file transfer. Designed with both usability and security in mind, the app enables end-to-end encrypted communication with embedded image file sharing that conceals payloads from unauthorized interception.
Core Features
• Real-time encrypted chat using AES-256 (CBC mode)
• Key exchange and session-based message encryption
• Steganographic file transfer: hides messages within image pixels
• Contact verification and secure identity initialization
• SQLite-based local chat history with encrypted storage
How It Works
Upon chat initiation, a unique session key is generated and shared securely. All messages are encrypted before transmission. When sending sensitive files, CryptChat embeds the payload within the least significant bits of PNG images using LSB steganography. The receiving device extracts and decrypts the hidden content, ensuring secure and covert delivery.
Security Design
• Advanced Encryption Standard (AES-256-CBC) with PKCS5 padding
• LSB Steganography for image-encoded message delivery
• Salted key derivation using PBKDF2 for enhanced resistance
• Input sanitization to prevent injection and tampering
Tech. Stack
Java, Android Studio, AES Encryption, Steganography, SQLite, XML UI Design, PNG LSB Encoding