iOS 10.3.1 (build 14E304) is an official Apple over-the-air update for the iPhone 5s (GSM), released on 2017-04-03T17:00:28Z. The update package is 572.79 MB. This is a delta (partial) update that requires 10.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 5c5db578802aa2f14eacc62a00123467d1c0dc6d.zip.