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=== SNVS modification ===
=== SNVS modification ===


Current Firmware version is stored in Syscon Secure [[Non Volatile Storage]]. SNVS is an area encrypted with per-console keys. SNVS encryption is handled by SAMU.
Current Firmware version is stored in Syscon SNVS. SNVS is an area encrypted with per-console keys. SNVS encryption is handled by SAMU.


See the research done by fail0verflow on PS4 Syscon. [https://fail0verflow.com/blog/2018/ps4-syscon]
See the research done by fail0verflow on PS4 Syscon. [https://fail0verflow.com/blog/2018/ps4-syscon]
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=== SPKG decryption ===
=== SPKG decryption ===


Modoru is a PS Vita Firmware downgrader made by TheFloW. It relies on the fact that PS Vita checks current Firmware version in its secure processor, but even on such error it decrypts successfully SPKG and returns data to kernel. All modoru has to do is to hook some functions in the updater. It does not require a secure processor hack at all, except for 3 things:
Modoru is a PSVita Firmware downgrader made by TheFloW. It relies on the fact that PSVita checks current Firmware version in its secure processor, but even on such error it decrypts successfully SPKG and returns data to kernel. All modoru has to do is to hook some functions in the updater. It does not require a secure processor hack at all, except for 3 things:
- when TheFloW made modoru, he had access to all PS Vita secure processor keys and binaries, allowing him to ensure downgrade would work. Doing it blind would have been dangerous for his tester' PS Vitas and he could not even have been sure it would work.
- when TheFloW made modoru, he had access to all PSVita secure processor keys and binaries, allowing him to ensure downgrade would work. Doing it blind would have been dangerous for his tester' PSVitas and he could not even have been sure it would work.
- when downgrading from a recent Firmware to a very old Firmware where SPKG keys where different: need old secure processor keys to decrypt SPKGs in modoru directly without asking secure processor as it does not contain these old keys.
- when downgrading from a recent Firmware to a very old Firmware where SPKG keys where different: need old secure processor keys to decrypt SPKGs in modoru directly without asking secure processor as it does not contain these old keys.
- when downgrading from a very recent Firmware, checks have been added in secure processor: need secure processor patching to bypass current Firmware check.
- when downgrading from a very recent Firmware, checks have been added in secure processor: need secure processor patching to bypass current Firmware check.


See PS Vita downgrader: Modoru by TheFloW. [https://github.com/TheOfficialFloW/modoru]
See PSVita downgrader: Modoru by TheFloW. [https://github.com/TheOfficialFloW/modoru]


== Official Current Firmware Version Bypass ==
== Official Current Firmware Version Bypass ==
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