iOS 7.1.2 (build 11D257) is an official Apple over-the-air update for the iPhone 4 (GSM / 2012), released on 2014-06-30T18:00:03Z. The update package is 158.9 MB. This is a delta (partial) update that requires 7.0.2 already installed. This update is currently signed by Apple, so it can be applied from Settings › General › Software Update.

Payload file: 63f11bf5ce7bbf6ec76acd2af2b589891dda1b82.zip.