iOS downgrade using TinyUmbrella Beta is highly possible.

TinyUmbrella tool was well known as the gateway to iOS downgrade back in iOS 5 and 6, where the SHSH blobs were being used for such matter.But after introducing a new called APTickets signature, Apple has win the battle again in restricting the downgrade process.

The good news here is, according to Semaphore TinyUmbrella has been rewritten, and a beta version has been released allowing users to save their current signed-in SHSH blobs for an upcoming downgrade.

Certainly, for users whom updated their devices to iOS 8.2 or a non jailbreakable version; won't benefit from the latest release of TinyUmbrella. But, it is really giving hope as the rules of the game has apparently changed in favor of the jailbreak community. 

The new tool requires Java environment to be run , and it need to be installed on your computer contrariwise as the previous version.A single button  " Fetch OTA for All " is now covering the whole process.

  Source : http://www.idownloadblog.com/