Many iOS encryption measures are not actually used, study finds

According to Johns Hopkins University cryptographers, iOS doesn't take advantage of built-in encryption as much as it could, leaving potential unnecessary security holes. Using public documents from Apple and Google, law enforcement reports on bypassing mobile security features, and their own analysis, the cryptographers assessed the robustness of iOS and Android encryption. The study found that while the encryption infrastructure on iOS sounds really good, it's largely unused.

Especially on iOS, this layered encryption infrastructure is already in place, and it sounds really great, but the researchers were very surprised to see how much it was not being used at the time. When an iPhone boots up, all stored data is in a completely protected state, and the user must unlock the device before anything can be decrypted. While this is very secure, the researchers stressed that once the device is unlocked for the first time after a reboot, a lot of data goes into a state that Apple calls "protected until first user authentication."

Since devices rarely reboot, most data is in a "protected until first user authentication" state rather than "fully protected" most of the time. The benefit of this less secure state is that the decryption keys are stored in fast access memory and can be quickly accessed by applications. In theory, an attacker could find and exploit certain types of security vulnerabilities in the iOS system to obtain encryption keys in fast access memory, enabling them to decrypt large amounts of data on the device. I believe this is also the working principle of many smartphone cracking access tools, such as those from forensic access company Grayshift.

While an attacker does need a specific operating system vulnerability to get the key, and both Apple and Google have patched many of these vulnerabilities as they are discovered, this could have been avoided by hiding the encryption keys deeper. "It really shocked me because I went into this project thinking these phones protected user data really well, and now I'm walking away from this project thinking almost nothing is protected," said Matthew Green, a cryptographer at Johns Hopkins University. "So why do we need a law enforcement backdoor if the protection these phones actually provide is so poor?"

The researchers also shared their findings and some technical recommendations directly with Apple. An Apple spokesperson made a public statement: "Apple devices are designed with multiple layers of security to protect against a variety of potential threats, and we are constantly working to add new protections for user data. As the amount of sensitive information stored by customers on their devices continues to grow, we will continue to develop more protections in hardware and software to protect their data."

The spokesperson also told Wired that Apple's security efforts are focused on protecting users from hackers, thieves, and criminals who want to steal personal information. They also pointed out that the types of attacks highlighted by the researchers are very expensive to develop, require physical access to the target device, and can only work until Apple releases a patch. Apple also emphasized that its goal for iOS is to balance security and convenience.