How to jailbreak iOS 8.0 to iOS 8.1.2

iOS 8.1.2 can be jailbroken using TaiG jailbreak tool.Take a backup of your device using iTunes or iCloud before proceeding. Jailbreaking your Apple device may void your warrant.Proceed  at your own risk.

Important
-Disable Passcode from Settings > Touch ID & Passcode(Settings -> General -> Passcode Lock On -> Turn Passcode Off). Also turn off Find my iPhone from Settings > iCloud > Find my iPhone.
-Please ensure you’ve updated iTunes to the latest version.
-Disable any Anti-virus programs or firewalls that could prevent TaiG from connecting to the internet.

Requirements:
Windows 7,8,10 (windows only)
TaiG Jailbreak Tool version 1.2.1
Latest version of iTunes
Reliable Internet connection.
A good condition Data cable . Original cable is better.

Supported devices:

Phone 6, iPhone 6 Plus, iPhone 5s, iPhone 5c, iPhone 5, iPhone 4S

iPad Air 2, iPad Air, iPad 4, iPad 3, iPad 2

iPad mini 3, iPad mini 2, iPad mini

iPod touch 5G

Guide:

Step 1: Download the  version 1.2.1 TaiG jailbreak from below TaiG website on your computer, and unzip the zip file.
http://www.taig.com/en/

Step 2: Connect your device to your computer using the USB cable.

Step 3: Please launch the application as an Administrator. Right click on the TaiG.exe and select the “Run as Administrator” option.

Step 6: TaiG will take some time to detect your device. Once you confirm that it is showing the correct firmware version, deselect the TaiG App Store (the one in Chinese), just below Cydia 1.1.16.

Step 7: Click on the green jailbreak (Begin or Start) button to proceed. You will see the circular progress bar.After the jailbreak is complete, your device will reboot automatically, and you should should see the Cydia icon on the Home screen.

Note: If TaiG gets stuck at 30% or so then don’t worry, wait for 20-30 minutes for the process to progress, it can take time if you’re using it in a virtual machine. Check this post for more details.

You can untether your device by intalling TaiG untether package from Cydia