Hacking A way to recompile/repack an PUP ? (PsVita Update)

[narutonic]

hello as the title says i want to know if it's possible to recompile an extracted PUP ?
And how the different files are checked ?

 

[Deleted User]

I don't think there's currently a way to recompile the PUP files yet. It would be possible, though.

 

[narutonic]

Ah... thought it could be possible to downgrade if there is a specific file which is checked when the update app open the PUP , and we just have to replace the file by the one which is in a more recent W.
But seems to simple to be true. Maybe in this file there are informations about the PKG's in the update or the pup is signed or anything else.

 

[cracker]

There is be some encryption involved to build a working PUP. Until the keys are found then it won't happen.

 

[Deleted User]

There is be some encryption involved to build a working PUP. Until the keys are found then it won't happen.

Would you need signing keys? Or just common keys? Or neither?

 

[cracker]

It seems there is an encrypted file hash in the header of the pup but the pkgs themselves will have encryption as well. The key(s) used to encrypt are probably changed every so often too to further avoid tampering just like other systems (PS3, PSP, etc.) have had done. They are always privately signed.