This is a college-level project: an end-to-end encrypted chat application built in Android Studio with a MongoDB back-end. All user accounts should authenticate strictly through email-and-password flow; no phone or social logins are needed. Core experience • One-to-one and group chats must be fully encrypted on the client before any data leaves the device, then stored in MongoDB in ciphertext. • Group chat creation, member invites, and message history sync are required. • Chats should support file sharing (images, documents, etc.), voice messages, and simple user-profile customisation such as avatar and status text. UI/UX Keep the interface clean and fast: a sign-in/sign-up screen, chat list, message view with attachments, and a lightweight profile edit screen. Material Design components are fine; originality is welcome but not mandatory. Deliverables 1. Complete Android Studio project (Java or Kotlin) with all source code. 2. MongoDB schema and sample data plus connection instructions (Atlas or local). 3. README explaining build steps, encryption approach, and how to run a quick demo on a fresh system. 4. Short video or screenshots demonstrating email sign-up, group creation, sending a file, and a voice note. 5. Final APK suitable for submission as a low-budget college assignment. Acceptance criteria • Message contents, file bytes, and voice data remain unreadable from the database or network logs. • Email registration/login works reliably, including password reset. • Group chat handles at least five members without crashes. • File and voice uploads under 10 MB complete in <10 s on a standard Wi-Fi connection. • All requested features compile and run cleanly in the latest stable Android Studio. I’m aiming to keep costs down, so clean, well-commented code and minimal third-party services are preferred over paid APIs. If a lightweight open-source library simplifies encryption or media handling, feel free to suggest it before integrating. Looking forward to seeing how you can wrap robust security and handy extras into a streamlined student-friendly budget.