Is Apple Deprecating Bitcode?

Understanding the Impact on Mobile App and API Security


In recent developments, Apple has announced its decision to deprecate Bitcode support for iOS apps, raising concerns about its implications for mobile app and API security. This blog post aims to provide a comprehensive understanding of this decision and its potential impact on the security landscape, while also highlighting security best practices to mitigate the risks.

I. Overview of Bitcode and its Importance in iOS Apps

Bitcode is an intermediate representation of an app's compiled code that allows Apple to optimize app performance and compatibility. It enables developers to upload apps to the App Store without targeting specific device architectures. Bitcode provides advantages like smaller app sizes, improved app optimization, and easier adoption of new device architectures.

II. Apple's Decision to Deprecate Bitcode

Apple's decision to deprecate Bitcode is driven by its ongoing efforts to streamline the app development process and improve the overall user experience. By eliminating the need for Bitcode, Apple aims to simplify the app review and approval process, reduce app download sizes, and enhance app performance.

However, this decision has significant implications for app developers and the security ecosystem as a whole.

III. Impact on Mobile App Security

The removal of Bitcode introduces potential vulnerabilities to mobile app security. Without Bitcode, apps become more susceptible to reverse engineering and code tampering, as attackers can analyze the app's static binary representation more easily. This increases the risk of intellectual property theft, unauthorized access to sensitive data, and the introduction of malicious code.

To mitigate these risks, developers can adopt several security best practices:

A. Binary Code Obfuscation:

Implementing code obfuscation techniques can make it harder for attackers to understand the app's logic and tamper with the code. This includes renaming variables and functions, adding junk code, and encrypting sensitive parts of the code. One notable advantage of binary code obfuscation is its compatibility with the iOS ecosystem. Unlike traditional obfuscation techniques that may not be fully compatible with iOS app development, binary code obfuscation techniques are specifically designed to work seamlessly within the iOS environment. By leveraging the unique characteristics of the iOS platform, binary code obfuscation can effectively protect the app's logic and sensitive code without introducing compatibility issues or compromising the app's functionality. This ensures that developers can implement robust security measures while maintaining the highest level of compatibility and performance on iOS devices.

B. Runtime Application Self-Protection (RASP):

Utilizing RASP solutions can provide an additional layer of security by monitoring the app's runtime environment and protecting against runtime attacks. RASP can detect and prevent code tampering, injection attacks, and unauthorized API calls. Using Approov's RASP integration also allows for dynamically updating security protocols, such that new emerging threats can be handed without the need to re-release the app through the App Store. 

IV. Impact on API Security

Bitcode plays a crucial role in API security measures. With its removal, API authentication and authorization mechanisms may become more vulnerable to exploitation. Attackers could potentially gain unauthorized access to APIs, compromise data privacy and integrity, and disrupt critical services.

To enhance API security in a Bitcode-deprecated environment, consider the following security best practices:

A. Dynamic Certificate Pinning:

Implementing dynamic certificate pinning can help ensure the authenticity and integrity of communication between the app and the API server. By validating the server's SSL certificate at runtime, developers can protect against man-in-the-middle attacks.

B. Runtime Secrets Protection:

Ensure that sensitive information, such as API keys and cryptographic secrets, are securely stored and managed at runtime. Utilize secure storage mechanisms, such as the Approov cloud service, which delivers secrets “just-in-time” to the app only at the moment they are required to make an API call, or an alternative secure enclave to protect secrets from unauthorized access.

C. Token-Based API Protection:

Implement token-based authentication mechanisms, such as OAuth or JWT, to secure API interactions. Token-based authentication provides an additional layer of security by reducing the reliance on session identifiers and enhancing the scalability of authentication processes.

D. Mobile App Attestation:

Leverage mobile app attestation services to verify the integrity and authenticity of the app at runtime. App attestation solutions detect and respond to tampering attempts, ensuring that only genuine and unmodified apps can communicate with protected APIs.

V. Conclusion

The deprecation of Bitcode by Apple introduces many challenges to both mobile app and API security. By implementing security best practices such as binary code obfuscation and adopting runtime protection mechanisms like RASP, developers can mitigate the impact of Bitcode deprecation on app security.

To enhance API security, dynamic certificate pinning, runtime secrets protection, token-based API protection, and mobile app attestation can be employed. These measures help ensure the integrity, confidentiality, and authenticity of API interactions.

While Apple's decision may pose initial challenges, it presents an opportunity for the security community to innovate and develop new techniques that ensure the safety of iOS apps and the protection of user data. Let us embrace these changes and work towards a more secure app ecosystem.