The full name of SHSH is Signature HaSH blobs, Chinese: Signature HaSH. Shsh is a certificate to verify the legality of iTunes firmware recovery operation. When we use iTunes to restore firmware, iTunes will submit the ECID of the firmware device to be restored to Apple's verification server, and apply for the shsh verification certificate to restore this version of firmware (that is, the shsh corresponding to each version of firmware is different and unique, such as version 4.3.2, version 4.3.3 and version 4.3.5), and Apple will send a shsh certificate corresponding to the ECID through the verification server.

Not backing up shsh means not backing up this version of signature verification, but it is only applicable to old devices. Because of A5 equipment, even if there is a backup of shsh, it cannot be degraded by shsh.