Tiny Umbrella is used to save SHSH blobs so that you can downgrade to earlier firmware by using it. For those who don't know SHSH blobs is a signature file which helps users to downgrade the older firmwares which Apple don't allow normally.
According to TinyUmbrella's blog:
“Before you ask; Yes a solution for the 5.x firmware nonce is being investigated… None of us have a working solution yet though. Hang tight. I have a couple trails and ideas I am trying out for 4.x baseband based restores to avoid 10xx errors. Until then save your signatures as you will never know when they may come in handy…"Download Links:
Download TinyUmbrella for Windows
Download TinyUmbrella for Mac