The blog post "Homomorphic Encryption in iOS 18" by Bastian Bohm details the introduction of homomorphic encryption capabilities within Apple's iOS 18 operating system, specifically focusing on the newly available APIs for performing calculations on encrypted data without requiring decryption. The author expresses excitement about this development, highlighting the potential for enhanced privacy and security in various applications.
The post begins by explaining the concept of homomorphic encryption, emphasizing its ability to process encrypted information directly, thus preserving the confidentiality of sensitive data. It distinguishes between Fully Homomorphic Encryption (FHE), which supports arbitrary computations, and Partially Homomorphic Encryption (PHE), which is limited to specific operations like addition or multiplication. The post clarifies that iOS 18 implements PHE, specifically focusing on additive homomorphic encryption.
The core of the post revolves around the newly introduced SecKeyEncryptedData class and its associated methods. The author provides a concise code example demonstrating how to create encrypted integers using this class and how to perform homomorphic addition on these encrypted values. The resulting sum remains encrypted, and only the holder of the decryption key can reveal its true value. The author meticulously breaks down the code snippet, explaining the role of each function and parameter. For instance, the post elucidates the process of generating a public key specifically designated for encrypted data operations and how this key is subsequently used to encrypt integer values. It also explains the significance of the perform method in executing homomorphic operations on these encrypted integers.
Furthermore, the post discusses the underlying cryptographic scheme employed by Apple, revealing that it leverages a variant of the Paillier cryptosystem. This choice is deemed suitable for integer additions and is acknowledged for its established security properties. The post also touches upon the practical limitations of PHE, specifically noting the inability to perform other operations like multiplication or comparison directly on the encrypted data without decryption.
Finally, the author speculates on the potential applications of this technology within the Apple ecosystem. The example given is privacy-preserving data collection, suggesting how homomorphic encryption could enable the aggregation of user statistics without compromising individual data privacy. This could be useful for applications like collecting usage metrics or accumulating health data while ensuring that the individual contributions remain confidential. The author concludes with an optimistic outlook on the future implications of homomorphic encryption within the iOS environment and expresses anticipation for further advancements in this field.
This blog post by Naehrdine explores an unexpected reboot phenomenon observed on an iPhone running iOS 18 and details the process of reverse engineering the operating system to pinpoint the root cause. The author begins by describing the seemingly random nature of the reboots, noting they occurred after periods of inactivity, specifically overnight while the phone was charging and seemingly unused. This led to initial suspicions of a hardware issue, but traditional troubleshooting steps, like resetting settings and even a complete device restore using iTunes, failed to resolve the problem.
Faced with the persistence of the issue, the author embarked on a deeper investigation involving reverse engineering iOS 18. This involved utilizing tools and techniques to analyze the operating system's inner workings. The post explicitly mentions the use of Frida, a dynamic instrumentation toolkit, which allows for the injection of custom code into running processes, enabling real-time monitoring and manipulation. The author also highlights the use of a disassembler and debugger to examine the compiled code of the operating system and trace its execution flow.
The investigation focused on system daemons, which are background processes responsible for essential system operations. Through meticulous analysis, the author identified a specific daemon, 'powerd', as the likely culprit. 'powerd' is responsible for managing the device's power state, including sleep and wake cycles. Further examination of 'powerd' revealed a previously unknown internal check within the daemon related to prolonged inactivity. This check, under certain conditions, was triggering an undocumented system reset.
The blog post then meticulously details the specific function within 'powerd' that was causing the reboot, providing the function's name and a breakdown of its logic. The author's analysis revealed that the function appears to be designed to mitigate potential hardware or software issues arising from extended periods of inactivity by forcing a system restart. However, this function seemed to be malfunctioning, triggering the reboot even in the absence of any genuine problems.
While the author stops short of providing a definitive solution or patch, the post concludes by expressing confidence that the identified function is indeed responsible for the unexplained reboots. The in-depth analysis presented provides valuable insights into the inner workings of iOS power management and offers a potential starting point for developing a fix, either through official Apple updates or community-driven workarounds. The author's work demonstrates the power of reverse engineering in uncovering hidden behaviors and troubleshooting complex software issues.
The Hacker News post titled "Reverse Engineering iOS 18 Inactivity Reboot" sparked a discussion with several insightful comments.
One commenter questioned the necessity of the inactivity reboot, especially given its potential to interrupt important tasks like long-running computations or data transfers. They also expressed concern about the lack of user control over this feature.
Another commenter pointed out the potential security implications of the reboot, particularly if a device is left unattended and unlocked in a sensitive environment. They suggested the need for an option to disable the automatic reboot for specific situations.
A different commenter shared their personal experience with the inactivity reboot, describing the frustration of having their device restart unexpectedly during a long process. They emphasized the importance of giving users more control over such system behaviors.
Several commenters discussed the technical aspects of the reverse engineering process, praising the author of the blog post for their detailed analysis. They also speculated about the potential reasons behind Apple's implementation of the inactivity reboot, such as memory management or security hardening.
One commenter suggested that the reboot might be related to preventing potential exploits that rely on long-running processes, but acknowledged the inconvenience it causes for users.
Another commenter highlighted the potential negative impact on accessibility for users who rely on assistive technologies, as the reboot could interrupt their workflow and require them to reconfigure their settings.
Overall, the comments reflect a mix of curiosity about the technical details, concern about the potential drawbacks of the feature, and a desire for more user control over the behavior of their devices. The commenters generally appreciate the technical analysis of the blog post author while expressing a need for Apple to provide options or clarity around this feature.
Summary of Comments ( 121 )
https://news.ycombinator.com/item?id=42666959
Hacker News users discussed the practical implications and limitations of homomorphic encryption in iOS 18. Several commenters expressed skepticism about Apple's actual implementation and its effectiveness, questioning whether it's fully homomorphic encryption or a more limited form. Performance overhead and restricted use cases were also highlighted as potential drawbacks. Some pointed out that the touted benefits, like encrypted search and image classification, might be achievable with existing techniques, raising doubts about the necessity of homomorphic encryption for these tasks. A few users noted the potential security benefits, particularly regarding protecting user data from cloud providers, but the overall sentiment leaned towards cautious optimism pending further details and independent analysis. Some commenters linked to additional resources explaining the complexities and current state of homomorphic encryption research.
The Hacker News post titled "Homomorphic encryption in iOS 18" spawned a modest discussion with a handful of comments focusing on the practicalities and limitations of the technology, rather than the announcement itself. No one expressed outright excitement or skepticism about the announcement, instead offering pragmatic observations.
One commenter pointed out that the homomorphic encryption being utilized is limited to integer addition and multiplication, and thus isn't fully homomorphic encryption (FHE) in the broader, more powerful sense. They clarified that true FHE allows arbitrary computation on encrypted data, which is not what Apple is implementing. This comment served as an important clarification to distinguish the specific type of homomorphic encryption being employed.
Another user expanded on this by mentioning that the specific technique used is called "additive homomorphic encryption" and likely leverages the Paillier cryptosystem. This added technical depth to the discussion, providing a potential underlying mechanism for Apple's implementation. They then speculated about its use case, suggesting it could be applied to scenarios like federated learning or aggregated metrics collection.
A subsequent comment explored the performance limitations of homomorphic encryption. The commenter noted the significant computational overhead associated with these techniques, which makes them unsuitable for many real-time or performance-sensitive applications. This comment highlighted the trade-offs involved in using homomorphic encryption, emphasizing that while it offers enhanced privacy, it comes at the cost of performance.
Finally, one commenter linked to a related project called "Concrete," further adding context to the types of operations and optimizations possible within the homomorphic encryption space. This provides an avenue for those interested in learning more about practical implementations and advancements in the field.
Overall, the comments section offers a concise and informed discussion focusing on the technical nuances of Apple's implementation rather than broad speculation or hype. They provide valuable context and clarification regarding the specific type of homomorphic encryption being used and its inherent limitations.