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[Question] Decrypt savedata?

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jl1990
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[Question] Decrypt savedata?

Post by jl1990 » Sun Mar 18, 2012 8:45 pm

Hi,

I had to sell my psp to buy the new psvita, i bought a psp game on store, and im trying to exploit it using savedata.
When i had my psp i could decrypt savedata through it, the problem is i sold mine.
I tried to use an emulator like JPCSP, but it didnt work, so do you know a way to decrypt psp (from psvita) savedata?

Thanks a lot

edit: i've already seen this post viewtopic.php?f=52&t=10804&p=132535&hil ... pt#p132535
but i couldnt find the duplicated post
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m0skit0
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Re: [Question] Decrypt savedata?

Post by m0skit0 » Thu Mar 22, 2012 9:11 am

jl1990 wrote:so do you know a way to decrypt psp (from psvita) savedata?
You can't.
jl1990 wrote: i've already seen this post viewtopic.php?f=52&t=10804&p=132535&hilit=decrypt#p132535
but i couldnt find the duplicated post
The duplicated post doesn't matter: there's no such thing.
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Re: [Question] Decrypt savedata?

Post by Disturbed0ne » Thu Mar 22, 2012 9:55 am

jl1990 wrote:edit: i've already seen this post viewtopic.php?f=52&t=10804&p=132535&hil ... pt#p132535
but i couldnt find the duplicated post
The thread was deleted. The user clicked "Submit" twice by accident causing the thread to be posted twice, it was a simple mistake. Nothing to be concerned about what so ever.
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Re: [Question] Decrypt savedata?

Post by wololo » Fri Mar 23, 2012 1:32 am

technically, with the work made on kirk last year, wouldn't it be possible to write a PC version of SED?
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Re: [Question] Decrypt savedata?

Post by wth » Fri Mar 23, 2012 1:42 am

if it were, that would really be awesome !
that way we could have programs modifying psp saves on their own and still outputting saves in the same encrypted format, meaning like no need for SGDeemer anymore at all to edit a savefile :)

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m0skit0
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Re: [Question] Decrypt savedata?

Post by m0skit0 » Fri Mar 23, 2012 9:58 am

wololo wrote:technically, with the work made on kirk last year, wouldn't it be possible to write a PC version of SED?
Hmmm, but aren't savegames encrypted with specific PSP key?
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Re: [Question] Decrypt savedata?

Post by wololo » Fri Mar 23, 2012 11:50 am

m0skit0 wrote:
wololo wrote:technically, with the work made on kirk last year, wouldn't it be possible to write a PC version of SED?
Hmmm, but aren't savegames encrypted with specific PSP key?
Yes and no. They can, but most games actually don't use the PSP key (which is why we can then read back a hacked savegame from any other psp). Not sure if it's a different function call, or if the game just passes a hardcoded value for the psp key.

So technically we could probably use one hardcoded psp key and that would work for "most" games.
I thin Virtua Fighter, and Gladiator begins, are some of the games I believe use the PSP key.
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Re: [Question] Decrypt savedata?

Post by m0skit0 » Fri Mar 23, 2012 12:26 pm

wololo wrote:Not sure if it's a different function call, or if the game just passes a hardcoded value for the psp key.
AFAIK, the game does not pass any hardcoded value (which btw would mean all savegames from that game would be the same, and thus useless to protect per device). Kirk does it using PSP ID (I think it's Syscon's ID or some hardware ID unique per PSP).
wololo wrote:I thin Virtua Fighter, and Gladiator begins, are some of the games I believe use the PSP key.
I think it's easier to do the first decryption step on PSP if needed, then you got the "universal" savegame, but still encrypted.

If anyone could point to a library to encrypt/decrypt PSP stuff, I can take a look. I believe the homebrew signer should be enough to do so, but I have no time to RE stuff...
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Re: [Question] Decrypt savedata?

Post by wololo » Fri Mar 23, 2012 12:50 pm

There's this one, but not sure how the kirk functions are related to psp savegames:
http://code.google.com/p/kirk-engine/source/list
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Re: [Question] Decrypt savedata?

Post by codestation » Fri Mar 23, 2012 5:06 pm

m0skit0 wrote: If anyone could point to a library to encrypt/decrypt PSP stuff, I can take a look. I believe the homebrew signer should be enough to do so, but I have no time to RE stuff...
The CryptoEngine from the jpcsp emulator can decrypt savedata (and other things) on PC, is easy as:

Code: Select all

byte out[] = new CryptoEngine().DecryptSavedata(savedata_byte_array, savedata_byte_array.length, gamekey, 0);
With just the classes at "src/jpcsp/crypto/", the Bouncy Castle Crypto API jar file and a quick wrapper class one can make a decrypter in 10 mins.

Sadly you still need a psp to hook the savedata function and retrieve the gamekey (that or know some mips and reverse a little around sceUtilitySavedataInitStart to get the gamekey from the eboot).
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