What is PSSE?
PSSE stands for PlayStation Suite Encrypted. It is an encryption layer that encrypts the PSM game's filesystem.
The encryption layer is comparable to the PS Vita Filesystem in many ways; however, it seemed that there was a bug at Sony, where besides executable files, the first directory level of a PSM app is not encrypted with PSSE, whose directory level is below the root of RO/. Similarly, the PSM SaveData is not encrypted by such layer either.
|0x00||0x50535345 (ASCII "PSSE")||Magic Number / File Header|
|0x14||CONTENT_ID||Contents of /RW/System/content_id|
|0x40||Signature||Generated by PSMSDK 'publisher key'? - Similar to sce_sys/clearsign file of NpDrm-Encrypted apps|
|0x180||Encrypted Keys||Generated by PSMSDK 'app key' and 'app seed'? - Similar to sce_sys/keystone file of NpDrm-Encrypted apps|
|0x680||Encrypted Data||Actual cipher-text for the encrypted file|