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TrustByte Solutions
Research & Academic CapstoneAcademic Capstone (CUST)
Context: CUST Software Engineering FYP II (Fall 2026)

Aegis Chat — Zero-Knowledge Secure Messaging & Threat Detection

Mobile and web secure messaging platform engineered at CUST implementing the Signal Protocol Double Ratchet algorithm for end-to-end encryption paired with privacy-preserving, on-device machine learning for real-time threat detection.

Aegis Chat — Zero-Knowledge Secure Messaging & Threat Detection primary technical interface or architecture overview
DisciplineCustom Software & Portals
Delivery StatusAcademic Capstone (CUST)
Primary StackFlutter
Project ScopeR&D Capstone

Authentic system diagrams, CAD models, and prototype artifacts documented from technical project reports and live deployments. Click any diagram to inspect full resolution.

Layered End-to-End Cryptographic Security Architecture (Signal Protocol E2EE & Relay Boundaries)System Schematic
Layered End-to-End Cryptographic Security Architecture (Signal Protocol E2EE & Relay Boundaries)
Double Ratchet Cryptographic Key Derivation & Message Transmission WorkflowTechnical Blueprint
Double Ratchet Cryptographic Key Derivation & Message Transmission Workflow
Native Flutter Secure Conversation Client with Verified Session Encryption StatusTechnical Blueprint
Native Flutter Secure Conversation Client with Verified Session Encryption Status
Contact Discovery, Verified Peer Keys & Active Session Management DashboardTechnical Blueprint
Contact Discovery, Verified Peer Keys & Active Session Management Dashboard

Problem Statement and Solution Architecture

Operational Need

The Problem & Constraints

Mainstream messaging platforms either inspect user content server-side to flag spam/phishing (violating user confidentiality) or remain completely blind to client-side threats. Aegis Chat solves this privacy-security paradox by executing threat classification locally on the device prior to message transmission.

Delivered Architecture

The Engineering Solution

Developed a Flutter application utilizing Libsignal / Signal Protocol Double Ratchet sessions, an encrypted SQLCipher local store, and an on-device TensorFlow Lite model that warns users of phishing, fraud, or coercive patterns without ever sharing decrypted plaintext with the relay server.

System Architecture & Operational Workflow

Flutter client (Android & Web) running SQLCipher and TFLite locally, communicating with a lightweight Node.js zero-knowledge relay server using WebSockets for encrypted ciphertext transit.

Step 01

Pre-Key Handshake

Clients upload signed pre-keys to the relay server; initiating sender computes shared master secret using X3DH.

Step 02

Double Ratchet Iteration

Every individual message advances the KDF chain, generating ephemeral symmetric keys for message encryption.

Step 03

Local Threat Evaluation

Inbound decrypted text is evaluated by local on-device TFLite model without network egress.

Step 04

Secure Cipher Persistence

Message history and ratcheted state are persisted into local AES-256 encrypted SQLCipher storage.

Key Subsystems & Functional Modules

Detailed breakdown of core software components, algorithms, and automated interfaces engineered for this project.

Forward Secrecy & Break-in Recovery

Ratchet keys rotate with every message, guaranteeing that a compromised key cannot decrypt past conversations.

Zero-Knowledge Relay Server

Server handles only blind ciphertext routing, preventing man-in-the-middle inspection.

Offline Machine Learning

TFLite classification runs in isolated device memory with 0 bytes transmitted to cloud APIs.

PIN & Biometric App Locker

Encrypted database access requires local authentication PIN verification.

Applied Technology Stack & Frameworks

Specific libraries, cloud services, and protocols utilized across the development lifecycle.

Client Application

Flutter 3DartProvider State Management

Cryptography & Data

Signal Protocol (Double Ratchet, X3DH)SQLCipher (AES-256)

On-Device AI

TensorFlow LiteQuantized Mobile NLP Classifier

Relay & Transit

Node.jsExpressWebSocketsFirebase Auth

Engineering Contribution

  • Co-developed by Muhammad Huzaifa Jawed and team at CUST; contributed to mobile Flutter UI architecture, Signal Protocol session lifecycle handlers, encrypted local SQLCipher migrations, and test harness.

Validation & Testing Evidence

  • Validated against automated cryptographic session teardown tests; verified offline ML inference speed (< 45ms per message on mobile); formal thesis defense and evaluation approved by CUST department faculty.

Technical Scope Transparency & Future Roadmap

TrustByte adheres to rigorous engineering ethics. We explicitly delineate verified production features from simulated models, proposed future integrations, or hardware constraints:

  • Implemented as an academic engineering capstone; cryptographic guarantees are verified against the documented reference Signal Protocol architecture and report benchmarks rather than an external commercial third-party audit.
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