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Miscellaneous Forums => Scripting and Reverse Engineering => Topic started by: Jedimark on 2010-08-07 12:58:08

Title: PSP .VMP Header - Checksum
Post by: Jedimark on 2010-08-07 12:58:08
Does anyone know much about the PSP save file format. In particular the header which appears to contain a 160bit checksum (SHA1??) which prevents you from modifying the data (PSP just re-formats the memory card). I wanted to adapt Jenova to edit FF7 save games created on the PSP.
Title: Re: PSP .VMP Header - Checksum
Post by: Bosola on 2010-08-07 14:21:26
Well, for a start, you should move to working with Black Choco rather than Jenova - it's newer, and also open source.

I know very little about the PSP save format. If the header looks like a SHA1 checksum to you, I'll take your word for it. You could always try to find an SHA hash generator, pipe in the data block, and see if it matches.
Title: Re: PSP .VMP Header - Checksum
Post by: Jedimark on 2010-08-07 15:12:48
Well I'm only guessing SHA1 because its 160-bit but who knows. The main problem is working out what bytes are used to calculate the checksum because it's certainly not all of them.
Title: Re: PSP .VMP Header - Checksum
Post by: sithlord48 on 2010-08-07 15:29:43
PSP saves are on our todo list, but i have been lazy about doing so.Mainly because i don't have a psp to test with. your more then welcome to hack w/ us on black chocobo,  you might want to start by checking out the exsisting code over on the SVN portion of the webpage (http://blackchocobo.sourceforge.net). in order to hack w/ us you will need to know C++. also we use Qt, so knowlege of that may be helpful (but its not required since its a Framework that uses C++)
Title: Re: PSP .VMP Header - Checksum
Post by: Jedimark on 2010-08-07 17:32:10
Very nice program, don't visit these forums very much these days but nice to see the community still going strong.
If you PM me your email address I can email you a VMP file to play with if you like.