This project presents the design and implementation of an innovative graphical authentication system for Android, replacing traditional alphanumeric passwords with a more intuitive and memorable image-based puzzle. The system enhances security and user experience by leveraging the human brain's superior ability to recognize and recall visual patterns. The application operates in two primary phases: registration and authentication. During registration, the user selects an image from their local device storage, which is then discretized into a tile-based puzzle. The correct arrangement of these tiles serves as the user's unique graphical password, which is stored locally on the device. For login, the same image is presented to the user in a scrambled state. The user must successfully reassemble the puzzle by rearranging the tiles to their original configuration. Upon successful authentication, the system does not merely grant access to the application itself but acts as a secure gateway, unlocking a secondary, restricted application—in this instance, a standard calculator app. This demonstrates a practical use case where the puzzle mechanism secures access to sensitive tools or data. By eliminating text-based credentials, the system mitigates risks associated with shoulder surfing and brute-force attacks. This project successfully establishes a functional prototype for a graphical password system, proving that a tile-rearrangement puzzle can serve as a robust and user-friendly authentication method for mobile platforms.

Keywords:  Android, graphical password, image puzzle, authentication, security, calculator unlock.