iOS 18 introduces homomorphic encryption for some Siri features, allowing on-device processing of encrypted audio requests without decrypting them first. This enhances privacy by preventing Apple from accessing the raw audio data. Specifically, it uses a fully homomorphic encryption scheme to transform audio into a numerical representation amenable to encrypted computations. These computations generate an encrypted Siri response, which is then sent to Apple servers for decryption and delivery back to the user. While promising improved privacy, the post raises concerns about potential performance impacts and the specific details of the implementation, which Apple hasn't fully disclosed.
iOS 18 introduces a new feature that automatically reboots devices after a prolonged period of inactivity. Reverse engineering revealed this is managed by the SpringBoard process, which monitors user interaction and triggers a reboot after approximately 72 hours of inactivity. The reboot is signaled by setting a specific flag in a system property and is considered a "soft" reboot, likely to maintain device state where possible. This feature seems primarily targeted at corporate devices enrolled in Mobile Device Management (MDM) systems, as a way to clear temporary states and potentially address performance issues resulting from prolonged uptime without requiring manual intervention. The exact conditions for triggering the reboot, beyond inactivity time, are still being investigated.
Hacker News users discussed the potential reasons behind iOS 18's automatic reboot after extended inactivity, with some speculating it's related to memory management, specifically clearing caches or resetting background processes. Others suggested it could be a security measure to mitigate potential exploits or simply a bug. A few commenters expressed concern about the reboot happening without warning, potentially interrupting ongoing tasks or data syncing. Some highlighted the lack of official documentation on this behavior and the author's reverse engineering efforts to uncover the cause. The discussion also touched on similar behavior observed in other operating systems and the overall complexity of modern OS architectures.
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.