.SHSH File Extension

System file used by iPhone and iPod Touch devices; saves authorization information for device firmware updates; saves information specific to each individual device and disables the ability for devices to downgrade their firmware.

SHSH files are sometimes used when "jailbreaking" iPhones and iPod Touch devices. When saved from a device, these files are sometimes used for loading downgraded firmware versions. Programs such as TinyUmbrella are used save the SHSH files.