With the rapid advancement of quantum computing, traditional cryptographic algorithms used in secure communication systems are becoming increasingly vulnerable to quantum-based attacks. This has created an urgent need for quantum-resistant security mechanisms to ensure long-term data protection. This project presents the design and implementation of a secure messaging platform based on Post-Quantum Cryptography (PQC), integrating the CRYSTALS-Kyber algorithm for secure key exchange, along with Advanced Encryption Standard for data encryption and Secure Hash Algorithm for data integrity verification. The system ensures End-to-End Encryption (E2EE) by encrypting messages and files at the sender’s end and allowing decryption only at the receiver’s end. Kyber, a lattice-based cryptographic algorithm, is employed to securely generate and exchange encryption keys resistant to quantum attacks. AES is used for efficient symmetric encryption of message content, while SHA ensures data integrity and authentication. The platform is structured into sender and receiver modules, enabling secure user registration, authentication, encrypted communication, file sharing, and message history tracking. Additionally, cloud storage is utilized to store encrypted data securely without exposing plaintext information. This project evaluates the effectiveness of post-quantum cryptographic techniques in real-world communication systems while addressing challenges such as computational overhead, key management, and system usability. By integrating quantum-resistant algorithms with efficient encryption methods, the proposed system provides a future-proof solution for secure digital communication in the era of quantum computing.

Keywords: Post-Quantum Cryptography (PQC), CRYSTALS-Kyber, AES, SHA, End-to-End Encryption (E2EE), Quantum Security, Secure Messaging, Data Privacy, Cloud Security, Key Encapsulation Mechanism (KEM)