Actually, I can think of one point: If using the same SN/AK would allow me to play with a different guild card on PC tan on DC, but the SN/AK is otherwise the same on the PC version save as it is in the DC version save, it might make it easier to figure out how the save files are encrypted. For example, what happens if I create a new character with the same name and the same SN/AK, but on PC? It would at least be interesting to compare the files. Second best case scenario they were lazy in making the PC version and just used a VMU save dump.BlueCrab wrote:Probably, but there's absolutely no point to doing so and it will not get the same guild card number as the Dreamcast copy on the server.
Yeah, I am seeing that, but thanks for confirming!BlueCrab wrote:The VMI file is useless for the most part, just ignore it (it's just metadata).
I think I figured out where it is, although I'd have to do a few more tests to be sure. As for how it works, still not sure, although I have my thoughts.BlueCrab wrote:You'd have to figure out where in the code of the game the encryption/decryption is performed and figure out how it works.
Yeah, I am fairly certain they are using Stream Encryption here. In which case the key cipher is probably derived from simple math done on the SN/AK. I doubt that they did anything complicated with the SN/AK though. For example, if they did some math on the SN and AK together that would mean that the console would either have to store that new key somewhere on the console or they'd have to do additional math every time the game saves and loads which could impair performance.BlueCrab wrote:It wouldn't surprise me that most of the data is the same, as Sega pretty much just used simple stream encryption without any salting all over the place in the game. If that is the case here (which I always suspected was the case), the only things that would be different between two copies of the save file from the same character would indeed be the bytes that are different in the plaintext before encryption (give or take a few around them for the block size of the encryption cipher).
If we could figure out, at the very least, exactly what change results in the character results in what change to the hex values and compare the results between multiple different SN/AK tests it should at least give enough information to take a character on one save and change it to match another on another save if nothing else, although best case scenario would be figuring out out to change it back to plain text and encrypt again which would allow you to change SN/AK even without having to create a new character on the new SN/AK.
My Dreamcast is modified with a dual BIOS switch and an overclock switch (that can't be used with GDEMU or DreamConn+). I also play with a VGA mod that I run through the HDMI adapter so I can play using my computer's video capture card which is how I get the screenshots. (Technically, if I wanted to, I could even setup a video channel of me playing Dreamcast games with my setup). The second BIOS was setup primarily to dump original discs through the serial port. I wonder if maybe there would be a way to set something up with the second BIOS to just listen for what the game does when it loads the character up. Like, dump the RAM or something. Although in that case I wonder if a Dreamcast emulator would work better, assuming any emulator supports the VMU files. Being able to see what the game is actually doing would probably help quite a bit.
That makes sense. And anyone who stuck with a game this long actually enjoys the grind. For some reason playing a dungeon crawler without effort somehow doesn't feel fun, although figuring out how to min max to reduce the effort does feel fun.BlueCrab wrote:I think it just has a lot to do with the fact that most of us playing the games now are older and wiser... and not a bunch of teenagers anymore.I assure you, PSO was pretty dern toxic, full of cheaters, pkers, etc. back in the day on Sega's servers (especially the US ones).
Now I wonder how people were able to cheat on the Dreamcast though. I didn't really play much online back in the day since I didn't have a reliable internet access (was still on a 28k modem and needed phone for other things) but I didn't know PKing was even a thing. Looking it up I heard about people somehow breaing into password protected parties to kill pople, and something called "NOLing" where they'd overwrite your character with an NPC named NOL somehow. (which, to be honest, shouldn't be that hard to avoid since you can just remove your VMU while playing and only insert when you want to save the game). How can the game be so locked down that we still don't have a decryption key for the saves today, yet decades ago people were able to do things like that? Was it just a game shark thing?
