AltStore

AltStore is an alternative app store for iOS devices that allows users to install applications that are not available on the official Apple App Store. Unlike jailbreaking, AltStore does not require modification of the iOS operating system's core. Instead, it leverages developer features within iOS to sideload apps.

Functionality

AltStore functions by using personal Apple Developer accounts to sign apps. Apple allows developers to sign up to three apps per Apple ID for testing purposes on their own devices. AltStore utilizes this mechanism to install and run apps directly on the device. This sideloading process requires the user to have access to a computer with AltServer installed, which facilitates the communication between the user's iOS device and Apple's servers for app signing.

AltServer

AltServer is a desktop application, available for both macOS and Windows, which is essential for using AltStore. AltServer is responsible for resigning the installed applications every seven days (for free Apple Developer accounts) or up to one year (for paid Apple Developer accounts). This resignation process is necessary to prevent the apps from expiring and becoming unusable. AltServer must be running on the same local network as the iOS device to perform this resigning process.

Limitations

AltStore's reliance on personal Apple Developer accounts imposes several limitations:

• Resigning Requirement: Apps installed through AltStore must be resigned regularly (typically every seven days for free accounts). This requires connecting the iOS device to the same Wi-Fi network as the computer running AltServer.
• App Limit: While Apple allows up to three apps to be signed per Apple ID, AltStore manages this limitation by resigning existing apps when a new one is installed, potentially requiring the user to prioritize which apps they want to keep active.
• Apple ID Dependency: The entire process is dependent on the user’s Apple ID. If Apple revokes the developer certificate associated with the Apple ID, all apps installed via AltStore will stop working until the certificate is renewed or a new one is obtained.

Use Cases

AltStore provides a platform for developers to distribute beta versions of their apps, and for users to install apps that Apple might reject from the App Store for various reasons, such as functionality that conflicts with Apple's guidelines. Common use cases include installing emulators, game modifications, or alternative media players. It can also be used to install developer builds of apps that are available on the App Store.

Security Considerations

While AltStore doesn't require jailbreaking, users should still be cautious about the apps they install. Apps from unofficial sources may pose security risks, including malware or privacy violations. Users are advised to only install apps from trusted developers and to be aware of the permissions requested by these apps.

Future Developments

Future development of AltStore focuses on improving the user experience, streamlining the resigning process, and potentially exploring alternative methods for app distribution within Apple's ecosystem.