Post: Understanding the RSA Signature
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05-10-2012, 02:36 AM
#1
Choco
Respect my authoritah!!
Understanding the RSA signature
I have noticed lots of confusion about this lately, so I wanted to post this to help clarify things for those who don't understand how the RSA signature works. With that being said, let's get started
-First off, there are two different keys used on the RSA signature: Public and Private. The public key is responsible for decrypting the RSA signature to check it, while the Private key is responsible for generating the RSA signature.
-In the Black Ops fastfile, the RSA signature starts at 0x3C and ends at 0x13B (giving it a total length of 256 bytes). Essentially, the RSA signature is a hash of the encrypted data contained inside the file. The signature is generated by Treyarch when they create the fastfile using their private key. If you change anything inside a fastfile at all, the RSA signature will not match the file and the game will abort loading the fastfile resulting in a blackscreen.
-So how does the game know that the RSA signature doesn't match the fastfile?
Well, the EBOOT.BIN (t5mp_ps3f.self for multiplayer) contains everything the game uses to load, and it includes a check on the RSA signature. So, in order to run a modded fastfile you need to modify the EBOOT.BIN to skip the RSA signature check. Lucky for you, I have already done this for everyone and you can download an EBOOT for your region with RSA signature checks removed You must login or register to view this content..
-So, why can't I just use a modded fastfile online?
If you have a modified fastfile you need a modified EBOOT, and as many of you probably know a modified EBOOT.BIN cannot be used on any firmware above 3.55. This is because Sony has changed the keys they use for encrypting executables after the whole custom firmware incident.
-Someone found the Public Key, so why can't they find the Private Key too?
The public key has it's name for a reason. Since the game cannot load an encrypted file, it has to decrypt it before runtime so the key has to be stored somewhere. The public key is contained inside the EBOOT.BIN and gets loaded into the SPU when you launch the game, and from there it is used to decrypt all fastfiles. The private key, however, is not stored anywhere in the game files. It is only used by treyarch to generate RSA signatures for their game update fastfiles.
This should help to clarify things for some of you, but if you have any questions feel free to ask. I hope you all learned something by reading
The following 33 users say thank you to Choco for this useful post:
ResistTheMoon, AMNE, blikefritz, BuC-ShoTz, Correy, DylanOc1, eazynow82, FaSt_FrEEdOm, Harry, ibombo, iLLy-i, KingcreekS, Kitty=^.^=, lbalancel, ljjp, lovebros, User23434, Ninja, Phrenzy, Press ►, primetime43, Cmd-X, rimka06510, SavageRising, Swampman, Taylor, Swifter, TheUnexpected, Uk_ViiPeR, Vectriixx, xMrSuperMoDzZ--, User2340034u
05-10-2012, 09:06 PM
#20
CodJumper:
I defeated!
Originally posted by ShoTz
choco the total length of the sig is 256 bytes (RSA256)
256 decimal = 0x100 hex
so basically the rsa sig is an unhackable hash/checksum
to decrypt the ff's the game uses the salsa20 key
the private key is what activision uses to make the rsa sig
the public key is what the game uses to verify the rsa sig
---------- Post added at 09:32 AM ---------- Previous post was at 09:28 AM ----------
its already online without the save key.
---------- Post added at 09:33 AM ---------- Previous post was at 09:32 AM ----------
mods are online just not a cl
------------------------------------------------------------------------------------------
now is anybody interested in modding MW3???????
could use some help...
256 decimal = 0x100 hex
so basically the rsa sig is an unhackable hash/checksum
to decrypt the ff's the game uses the salsa20 key
the private key is what activision uses to make the rsa sig
the public key is what the game uses to verify the rsa sig
---------- Post added at 09:32 AM ---------- Previous post was at 09:28 AM ----------
its already online without the save key.
---------- Post added at 09:33 AM ---------- Previous post was at 09:32 AM ----------
mods are online just not a cl
------------------------------------------------------------------------------------------
now is anybody interested in modding MW3???????
could use some help...
Wait i'm sorry he just said "as many of you probably know a modified EBOOT.BIN cannot be used on any firmware above 3.55. This is because Sony has changed the keys they use for encrypting executables after the whole custom firmware incident" So why are we focused on the Game data utility when people have already cracked the save data utility. Yes it won't be a challenge lobby but you can still do xp, ufo, god mode ext.. I know because i have been in these lobbies.. This could lead up to modding Mw3 One cod at a time.
I knew this anyway but great for people who didnt
05-10-2012, 09:19 PM
#22
Newelly
Guest
Originally posted by .Choco
Understanding the RSA signature
I have noticed lots of confusion about this lately, so I wanted to post this to help clarify things for those who don't understand how the RSA signature works. With that being said, let's get started
-First off, there are two different keys used on the RSA signature: Public and Private. The public key is responsible for decrypting the RSA signature to check it, while the Private key is responsible for generating the RSA signature.
-In the Black Ops fastfile, the RSA signature starts at 0x3C and ends at 0x13B (giving it a total length of 256 bytes). Essentially, the RSA signature is a hash of the encrypted data contained inside the file. The signature is generated by Treyarch when they create the fastfile using their private key. If you change anything inside a fastfile at all, the RSA signature will not match the file and the game will abort loading the fastfile resulting in a blackscreen.
-So how does the game know that the RSA signature doesn't match the fastfile?
Well, the EBOOT.BIN (t5mp_ps3f.self for multiplayer) contains everything the game uses to load, and it includes a check on the RSA signature. So, in order to run a modded fastfile you need to modify the EBOOT.BIN to skip the RSA signature check. Lucky for you, I have already done this for everyone and you can download an EBOOT for your region with RSA signature checks removed You must login or register to view this content..
-So, why can't I just use a modded fastfile online?
If you have a modified fastfile you need a modified EBOOT, and as many of you probably know a modified EBOOT.BIN cannot be used on any firmware above 3.55. This is because Sony has changed the keys they use for encrypting executables after the whole custom firmware incident.
-Someone found the Public Key, so why can't they find the Private Key too?
The public key has it's name for a reason. Since the game cannot load an encrypted file, it has to decrypt it before runtime so the key has to be stored somewhere. The public key is contained inside the EBOOT.BIN and gets loaded into the SPU when you launch the game, and from there it is used to decrypt all fastfiles. The private key, however, is not stored anywhere in the game files. It is only used by treyarch to generate RSA signatures for their game update fastfiles.
This should help to clarify things for some of you, but if you have any questions feel free to ask. I hope you all learned something by reading
I still don't understand :carling:
05-10-2012, 10:27 PM
#26
Swampman
Luvin' Da Cajun Life
Originally posted by caleb01
Wait...So since the black ops isnt being modified by the eboot, but is instead being modded through the game's save data, does that mean we don't need a ps3 with modified firmware on it? My little brother upgraded my ps3 
Correct, it can be done without a jailbroken system. But it will not get released.
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