Secure Mobile Device Recovery Architecture

MD Finder gives you ultimate control over your device's security. Whether your phone is under a couch cushion or in the wrong hands, you can track it, lock it, or wipe it instantly with a single SMS even without an active internet connection.."

DOWNLOAD APPLICATION

// Technology Stack

Android (Java)

REST API

PostgreSQL

HTTPS / TLS

Authentication

Server Validation

Linux Hosting

Git & GitHub

// System Architecture

[ Android Client ]
        │
        │  HTTPS (TLS Encrypted)
        ▼
[ REST API Server ]
        │
        │  Secure Query Handling
        ▼
[ PostgreSQL Database ]

The system follows a secure client-server model. All remote commands require authenticated sessions and server-side validation before execution. No command is trusted without verification.

// Features & Usage

Installation

✔ Download the latest release from the DOWNLOAD APPLICATION link
✔ Note: you might have to temporarly pause Google play-protect services on installation
✔ Complete the System Protection Initialization (Onboarding) to grant necessary permissions.
✔ Keep the MD Finder Active notification visible to ensure persistent protection.

Key Features

✔ Real-time monitoring of battery health, network carrier, screen state, and movement.
✔ Control your device from any other phone using secure, PIN-authorized SMS commands.
✔ Bypass system volume to trigger a maximum-decibel alarm to locate your device nearby.
✔ Remotely lock your screen and arm an auto-wipe policy that triggers after 5 failed unlock attempts.
✔ Intelligent location recovery using cached GPS data when active services are disabled.

Commands

Command	Action	Description
`HELP`	Get Guide	Returns this command list (No PIN required).
`LOCATION`	Track	Fetch coordinates, battery, carrier, and map link.
`SCREENLOCK`	Safe Lock	Instantly locks the screen without auto-wipe risk.
`ALARM`	Find	Triggers the max-volume tactical siren.
`ALARMSTOP`	Silence	Disarms and silences the active siren.
`ARMED-LOCK`	Secure	Locks screen and arms Auto-Wipe (5 attempts).

How to send a command

To control your device remotely, send an SMS to your number using the following format: `COMMAND [YourPIN]`
Example
To lock down the device, send: SCREENLOCK [YourPIN] This will remotely lock the device.

// Security Design Principles

Authentication & Authorization

✔ Password hashing
✔ Session validation
✔ Access control enforcement

Secure Communication

✔ HTTPS/TLS encryption
✔ Server-side input validation
✔ Sanitized database queries

Defensive Coding

✔ Principle of least privilege
✔ Controlled background execution
✔ Error handling & logging

Data Protection Awareness

✔ User-controlled account deletion
✔ Minimal data collection
✔ Secure storage practices

// Engineering Focus

This project was developed to strengthen skills in full‑stack development and secure system architecture. It explores real‑world concerns such as authentication flows, API hardening, database integrity, and mobile background services. The emphasis is on writing secure, maintainable, and well‑structured code.

// Responsible Use

This repository is intended for educational and portfolio purposes only. The software should only be installed on devices owned or authorized by the user. The project is designed to demonstrate secure development practices — not to bypass platform protections or enable unauthorized monitoring.