TinyUmbrella is a combination of two earlier tools:
- Umbrella -- used to save the SHSH certificate file of your iPhone to make it possible to later downgrade the firmware. It even works with non-jailbroken devices.
- TinyTSS -- used to start the replay attack to downgrade the firmware. Only needed if Saurik's server is not available and you have the SHSH certificates saved locally.
TinyUmbrella requires Java to be installed (on Windows systems requires 32-bit Java version).