It sounds like you're referring to (a common typo: "shsh" instead of "SHSH").
SHSH blobs are digital signatures used by Apple to verify iOS/iPadOS firmware restores. They are essential for downgrading an iPhone, iPad, or iPod touch to an older, unsigned iOS version.
Shsh Blobs !!link!! Site
It sounds like you're referring to (a common typo: "shsh" instead of "SHSH").
SHSH blobs are digital signatures used by Apple to verify iOS/iPadOS firmware restores. They are essential for downgrading an iPhone, iPad, or iPod touch to an older, unsigned iOS version. shsh blobs