So I was browsing around the other day and found that the author of Fightcade had posted some information on how to re-encrypt CPS2 ROMs, which is quite useful for ROM hacks.
He has a Youtube video from a conference here, as well as a PDF posted as "r2con_PauOliva_Hacking_StreetFighter_CPS2_Encryption_FINAL.pdf".
Page 38 has the details on how to encrypt CPS2 roms. While r2hash didn't work for me (for some reason it makes the ROMs larger?), I was able to build a modified MAME binary for properly re-encrypting CPS2 roms using his info.
Here's how it works:
1) Adjust MAME source code to encrypt instead of decrypt.
2) Apply modified instructions (decrypted) to a given encrypted CPS2 rom.
3) Load up in modified MAME build (pass -window -debug), go to "Debug" -> "New Memory Window" -> select decrypted_opcodes in dropdown, navigate to your modified region and there's your encrypted code.
4) Apply the encrypted instructions over your decrypted ones in the ROM, load up with normal MAME and test.
Here's a couple of my ROM hacks (one is brand new and by request!) that work with the encrypted ROMs on the CPS2 multi.
Note that ONLY xdeltas are provided, no ROMS! You must have the original ROMs and use "xdelta UI" to apply the changes against your existing files.
For completeness, the zips have xdeltas for both encrypted and decrypted ROM sets on both CPS2 multi and ROM board formats.
Hope you guys enjoy! I may slowly work on converting my other CPS2 hacks (e.g. Marvel VS character unlocks) for encrypted sets and will keep this thread updated if/when I do.
The decrypted Avalaunch sets are great and work just fine IMO, but with the CPS2 multi now supporting encrypted sets and it being easy to apply hacks against the original ROMs - why not? In the case of Dimahoo there is only one modified instruction, so it's the best of both worlds in terms of playing the game how the developers intended and also being able to select the hidden characters easily.
He has a Youtube video from a conference here, as well as a PDF posted as "r2con_PauOliva_Hacking_StreetFighter_CPS2_Encryption_FINAL.pdf".
Page 38 has the details on how to encrypt CPS2 roms. While r2hash didn't work for me (for some reason it makes the ROMs larger?), I was able to build a modified MAME binary for properly re-encrypting CPS2 roms using his info.
Here's how it works:
1) Adjust MAME source code to encrypt instead of decrypt.
2) Apply modified instructions (decrypted) to a given encrypted CPS2 rom.
3) Load up in modified MAME build (pass -window -debug), go to "Debug" -> "New Memory Window" -> select decrypted_opcodes in dropdown, navigate to your modified region and there's your encrypted code.
4) Apply the encrypted instructions over your decrypted ones in the ROM, load up with normal MAME and test.
Here's a couple of my ROM hacks (one is brand new and by request!) that work with the encrypted ROMs on the CPS2 multi.
Note that ONLY xdeltas are provided, no ROMS! You must have the original ROMs and use "xdelta UI" to apply the changes against your existing files.
For completeness, the zips have xdeltas for both encrypted and decrypted ROM sets on both CPS2 multi and ROM board formats.
- Dimahoo / Great Mahou Daisakusen - All Characters Unlock
- Progear / Progear no Arashi - Second Loop Hack
Hope you guys enjoy! I may slowly work on converting my other CPS2 hacks (e.g. Marvel VS character unlocks) for encrypted sets and will keep this thread updated if/when I do.
The decrypted Avalaunch sets are great and work just fine IMO, but with the CPS2 multi now supporting encrypted sets and it being easy to apply hacks against the original ROMs - why not? In the case of Dimahoo there is only one modified instruction, so it's the best of both worlds in terms of playing the game how the developers intended and also being able to select the hidden characters easily.
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Only other thread I could find was the one Smokemonster opened back in 2016: 
