Talk:CXI

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How 3DS system judge encryption type? --Matyapiro

Sorry the question is not understood. What do you mean? --Neimod
I think that he means "How does the 3DS decide what encryption method must be used" --Quincy 23:47, 29 May 2011 (CEST)
That question does not make sense. There are no decisions. It is always AES CTR. --Neimod

Sorry,how does the 3DS decide what key to use for encryption? --Matyapiro

If you figure that out, let us know, thanks. --Neimod 02:45, 1 June 2011 (CEST)

There's a common key used to generate output at compile time, when the cci/ctx files are made. Why do you say 128 bit AES CTR though? --Jl12

Because 128-bit AES CTR is used to encrypt those formats. --Neimod 15:40, 18 June 2011 (CEST)

I know *something* is used to encrypt but do we know it is 128 bit AES CTR? --Jl12

Frankly I don't think it was AES. I think it's using RSA for encryption. Besides it already used it once for the 2048-bit signature as you said. Wouldn't it make way more sense to also use it for the encryption scheme. --Jl12

Lol. --Neimod 16:06, 20 June 2011 (CEST)

What's funny? So I guess it's just based purely on speculation? You should say so. That way nobody believes something that isn't right. --Jl12 22:28, 20 June 2011 (CEST)

RSA is only used for the signature. After that a symmetric block cipher called AES is used in CTR mode. --Neimod 23:32, 20 June 2011 (CEST)


How did you get this data? Did you find some way to dump 3DS cartridges? --Popoffka 09:15, 1 June 2011 (CEST)

Yes, someone found a way to dump the data on 3DS cards. Unfortunately the method cannot be disclosed, and at this point dumping is not really useful since most of the information is encrypted. --Neimod 10:03, 1 June 2011 (CEST)

Do you have any method to run a Dump? and did you find the key for the ctrtool? --Stevechou

Nope on both questions. --Neimod 17:33, 25 June 2011 (CEST)

There's code in ctrtool that takes the AES counter value from some partition ID and type. I can't help but wonder, how do you know that the counter value is generated this way? And if we know that, isn't it a start to finding out the key? --Luigi2us 20:17, 25 June 2011 (CEST)

Sorry this information cannot be disclosed. --Neimod 05:17, 27 June 2011 (CEST)

Anyway, can you read the encrypt datas?


Hi! Do we already know where the offset of the ARM11 code is? And that I got correctly, that the hole 3DS ROM encrypted by AES? --Lazymarek9614 21:10, 1 August 2011 (CEST)

Yes, see ctrtool for more exact details. --Neimod 17:44, 6 September 2011 (CEST)

Hi Neimod, love your work! my question is: The extended header suppose to start right after the NCCH header so why there is twice the space? (extended header size is usually 1024 and plain region offset is usually 5*512 = 2560 -> 2048 after the end of the ncch) thanks. --Elisherer 11:46, 6 September 2011 (CEST)

I'm not sure I understand you. The extended header does come right exactly after the NCCH header. The only place where this does not hold is the NCCH header at offset 0x1000, but this one header should be ignored because this space does not exist on a real card. I suspect this is the plaintext header from command 0x82 that was injected into the ROM in post-processing by the dumpergroup. --Neimod 17:40, 6 September 2011 (CEST)

I have a simple question why Neimod are thinking the code is compressed? I think LZSS is not good for binary images.

Because they just are. --Neimod 17:40, 6 September 2011 (CEST)
Game editors want to fit their game in the smallest ROM chip size possible, to reduce manufacturing costs. Also, encrypting blocks of zeros/FF is bad practices, compression avoids it. --Luigi2us 18:17, 6 September 2011 (CEST)