iOS 12.0 (build 16A5365b) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2018-08-27T17:02:50Z. The update package is 55.82 MB. This is a delta (partial) update that requires 12.0 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 111c2108d453d53296d8776cea49e63ca296f438.zip.