How To Downgrade iOS 10.3.x To iOS 10.2.1 / 10.2 For Jailbreak Purposes
Here’s how to downgrade iOS 10.3.3 to iOS 10.2 / iOS 10.2.1 without having to have a jailbreak in place, and then jailbreak using yalu or Saigon.
This method relies on using the v0rtex bug found by S1guza and requires you to have SHSH2 blobs already saved for the version of firmware that you are looking to downgrade to.
There are a few things that you will need in order to successfully go through this process, including access to Cydia Impactor, the necessary IPA file of the app that has been built to exploit the S1guza v0rtex bug, and, of course, an iOS device running iOS 10.3.x. As mentioned earlier, you’ll also need your SHSH2 blobs saved for the firmware you are downgrading to, which in this case will be for 10.2.1 or 10.2.
It is important to note that this process supports iPhone 5s, iPhone 6/6s, iPhone SE, and iPhone 7/7 Plus.
Step 1: Download the necessary v0rtexNonce IPA file from here.
Step 2: This initial part of the process will involve having your iOS device connected to your PC or Mac and using Cydia Impactor to install the IPA file. To do this, drag the previously downloaded IPA file into Cydia Impactor and verify with a valid Apple ID and password to proceed. For detailed instructions on how to install the said IPA file on your iOS device using Cydia Impactor, you can always check our guide here: Sideload iOS Apps On Windows, Mac With Cydia Impactor Without Jailbreak, Here’s How.
Step 3: Once the app has been sideloaded, you will need to go to Settings > Profile(s) & Device Management and then trust the installed profile to allow iOS to run the sideloaded app.
Step 4: Once this is all done, locate your SHSH2 blobs for iOS 10.2.1 or 10.2 and open the .SHSH2 file with notepad or any editor of your choice. Scroll down to the bottom until you see the generator key sandwiched between <key></key>. Underneath that, you will find an associated string which is the value that you’ll need. Copy this string.
Step 5: Now launch the v0rtexNonce app on your iOS device and paste the copied generator value into the ‘Set Generator‘ section in the app. Hit Enter to proceed once that Generator value has been set.