PhotoFolder: Secure Document Locking and Viewing App

Securely lock and view private documents with PhotoFolder app

Safety/ Security

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Key takeaways

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PhotoFolder is an application designed to keep your documents locked and allow you to view them privately. Developed in a B2C environment using Xcode and Objective-C, the app utilizes the MVC framework, Realm database, and Reactive programming. It is compatible with iOS 8.0 and later.

The client required an app that could securely lock private files, including audio and video content. The app needed to support encryption, sync across multiple devices, and ensure access was restricted to authorized users. It also needed premium features like removing advertising banners, a flip-to-hide feature, fake PINs, break-in alerts, and cloud synchronization.

The developers chose Realm Mobile Database for its efficient synchronization capabilities. This choice accelerated development and enabled features like the PIN screen, which activates each time the app closes. To unlock the screen, users can use Touch ID or enter a PIN. Additionally, a fake mode requires a fake password, displaying standard content while hiding the locked content.

The auto-renewable subscription system was implemented with a remote server. The app uses AES-256+SHA2 encryption with a 64-byte key, verified through the SHA-2 HMAC protocol. The Touch ID option was implemented using the standard Local Authentication framework, simplifying access when the app is in background mode.

The app allows data storage on the Realm server, data syncing, folder creation, and management. Users can save, import, export, and delete photo and video content within chosen folders. Folder configurations include cover selection, name editing, and password setup. Application settings allow password editing, email configuration, and management of in-app purchases. Premium features, available after purchase, include ad removal, flip-to-hide, fake PINs, break-in alerts, and cloud synchronization. If the wrong password is entered three times, the app blocks access for five minutes.

The development resulted in a user-friendly application that securely locks private audio and video content with high-level encryption. The Realm database enables cloud storage through iCloud, Dropbox, and Amazon. Touch ID provides a convenient unlock method, and the app can synchronize with multiple devices.

Rrahul Sethi
May 30, 2024
5 min read