| Device Age | Unsigned Restore Possible? | Free Tool Required | | :--- | :--- | :--- | | iPhone 4s – iPhone X (A5–A11 chips) | ✅ Yes, using checkm8 exploit | , iOS-OTA-Downgrader , Vieux | | iPhone XS – iPhone 14 (A12–A16) | ❌ No permanent downgrade without SHSH blobs | Limited, requires saved blobs | | iPhone 15+ (A17 Pro) | ❌ No | None |
Restoring an unsigned IPSW is technically impossible for the average user because Apple must provide a digital signature (SHSH blob) to authorize the installation. Once Apple "unsigns" a firmware version, their servers will no longer provide this authorization, causing standard tools like iTunes and Finder to block the process. unsigned ipsw restore tool free