This is the most complete video tutorial you can find on the internet about creating the CFW (Modified IPSW) using iBEC, IBSS and ASR Patches and using F.C.E. 365 Firmware Manager to Decrypt / Encrypt DMGs and IMG3 files.
The concept idea is simple: You modify the IPSW and restore it without Setup.app and therefore you skip activation.
The tutorial is beginner friendly, and as you can see is up to date as we use iPhone 5,2 and iOS 9.2.1 IPSW.
For this operation you need to have the keys for ROOT, Ramdisk and DFU / IMG3 files from The iPhone Wiki.
This Tutorial is provided "as-is" without any guarantee and any responsibility. You are the only one liable for the usage of the information provided here for Educational purpose only.
Links are taken from my other video description, sorry for the ad, too lazy today to reupload the tools.
F.C.E. 365 Firmware Manager: https://www.theiphonewiki.com/wiki/F.C.E._365_Firmware_Manager
Keys and IPSWs: https://www.theiphonewiki.com/wiki/Firmware
This is how to restore the CFW created using libimobiledevice:
This is my successful attempt on an iPhone 5:
Thanks for watching. Good luck!