iOS 6.1.3 (build 10B329) is an official Apple over-the-air update for the iPhone 4 (CDMA). The update package is 74.83 MB. This is a delta (partial) update that requires 6.0.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f9d57bf32b73050520540d123371a41db04c3818.zip.