PlayStation 4 developer @DimosGsxR let us know he'd like to share his UnFSelf Windows application to convert PS4 FSELF files back to ELF files by simply dragging and dropping the FSELF file on UnfSelf.exe to get the resulting ELF file with "-decrypted" added to the filename. 
Download: unfself.zip (21.7 KB) / unfself.zip (Mirror) / UnfSelf.exe (51.0 KB) / selfutil.zip (1.59 MB - includes selfutil.exe) by @zezu420 (aka Znullptr on Twitter or dmiller423 on Github) / SelfUtil.exe (Compiled by RetroGamer_74) / Selfutil_PS5.exe
For those curious the Greek sentence in the prompt roughly translated states "Please enter the location of the file:" which isn't necessary if you drag and drop it, however, like me you may need to install Microsoft Visual C++ 2015 Redistributable Update 3 RC to run it.
Here's more details from his email earlier today, to quote: Guys I have made a tool to convert FSELF back to ELF. That will be useful for PS4 <5.05 to unself FSELF and lower firmware on games.
I tested and confirmed the ELF file from my program is same with dumped ELF from PS4 dumped payload.
The program is simple, no UI just drag n drop FSELF file on program and you get same name file with "-decrypted" ELF file.
You can drag multiple files at same time but need all files to be FSELF else the program is close. Just try yourself to be sure. I am not a pro development just learning C++.
I made that because I didn't want to upgrade 4.55-> 5.05, but because no one shared the ELF file from games to patch it lowering FW. Nevermind now I am on 5.05 but that will be useful for those guys who haven't upgrade.
Try it and check if decrypted FSELF files from that program is equal with PS4dump payload ELF files (all test I have done it's equal).
The process is:
Step 1) extract fake PKG
Step 2) get the FSELF files from extracted PKG
Step 3) drag and drop to program
Step 4) do mods on ELF file (ex. lowering FW)
Step 5) rebuild PKG
I hope that will be useful for someone. As I say before I just beginner C++ programmer.
orbis-ld --fself-flags= >>> Set the fself flags specified.
Possible values are "videoservice" and "nongame"
Download: unfself.zip (21.7 KB) / unfself.zip (Mirror) / UnfSelf.exe (51.0 KB) / selfutil.zip (1.59 MB - includes selfutil.exe) by @zezu420 (aka Znullptr on Twitter or dmiller423 on Github) / SelfUtil.exe (Compiled by RetroGamer_74) / Selfutil_PS5.exe
For those curious the Greek sentence in the prompt roughly translated states "Please enter the location of the file:" which isn't necessary if you drag and drop it, however, like me you may need to install Microsoft Visual C++ 2015 Redistributable Update 3 RC to run it.
Here's more details from his email earlier today, to quote: Guys I have made a tool to convert FSELF back to ELF. That will be useful for PS4 <5.05 to unself FSELF and lower firmware on games.
I tested and confirmed the ELF file from my program is same with dumped ELF from PS4 dumped payload.
The program is simple, no UI just drag n drop FSELF file on program and you get same name file with "-decrypted" ELF file.
You can drag multiple files at same time but need all files to be FSELF else the program is close. Just try yourself to be sure. I am not a pro development just learning C++.
I made that because I didn't want to upgrade 4.55-> 5.05, but because no one shared the ELF file from games to patch it lowering FW. Nevermind now I am on 5.05 but that will be useful for those guys who haven't upgrade.
Try it and check if decrypted FSELF files from that program is equal with PS4dump payload ELF files (all test I have done it's equal).
The process is:
Step 1) extract fake PKG
Step 2) get the FSELF files from extracted PKG
Step 3) drag and drop to program
Step 4) do mods on ELF file (ex. lowering FW)
Step 5) rebuild PKG
I hope that will be useful for someone. As I say before I just beginner C++ programmer.
orbis-ld --fself-flags= >>> Set the fself flags specified.
Possible values are "videoservice" and "nongame"
Code:
orbis-bin.exe --dump-fself-info file.elf Flag Value Non-game 0 Video service 0