iOS 8.1 (build 12B411) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2014-10-20T17:59:09Z. The update package is 1.18 GB. This is a delta (partial) update that requires 7.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 6024da2143b26d4db181751c8fa52672f0c8a8b1.zip.