TSSChecker is a useful tool developed by tihmstar for saving SHSH2 blobs of an iOS firmware so that you can later on downgrade to that firmware once Apple stops signing it. Apparently, there was an issue with the tool that generated incorrect SHSH2 blobs for iPhone 7 and iPhone 7 Plus. But the good news is that tihmstar has fixed that issue in the latest version of TSSChecker, so you can now go ahead and use the tool to save the correct SHSH2 blobs for these devices.
The fact that tihmstar quickly worked on this issue and released an update in just a week is encouraging for the tool’s longevity going forward, and perhaps in a few months’ time, the iOS 10.2 blobs which can now be correctly saved are the ones everyone will need, for example to downgrade from 10.3 to 10.2 to jailbreak.
The original fault with TSSChecker lay in the fact that the iPhone 7(+) derives its nonces differently from the generator in comparison to other devices. Without having been able to test this, tihmstar was initially unaware, and so the tool attempted to save APTickets with a generator in the same way as it did with all other devices, leading to invalid blobs. When he discovered the fault, he was unable at first to work out what method the iPhone 7(+) was using to create its nonces from its generators, but given a few days’ work and some collaboration with Luca Todesco, the problem was resolved. TSSChecker v170 and higher are now capable of correctly saving iPhone 7(+) blobs with a generator again.
As of this writing, Apple is signing iOS 10.2 so you can only generate SHSH2 blobs for this firmware only. If you had saved iOS 10.1.x SHSH2 blobs previously for iPhone 7 using the old TSSChecker version, then unfortunately they are not valid.
The popular tool TSSSaver has been updated to use the latest TSSChecker, so that is probably the quickest way to re-save your iPhone 7(+) blobs if you wish to. Please remember that “futurerestore” is not yet compatible with iPhone 7(+), though support is supposedly coming.
The current beta of Yalu jailbreak supports iOS 10.1 – iOS 10.1.1. The jailbreak is not stable and contains a number of issues that could create problems on your device. It is recommended that you stay put and wait until Luca releases a stable version of this jailbreak. We will keep you updated as soon as this happens.