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Line 1: − 3DSのセーブデータはゲームカートにまさにDSと同じように保存されています。 − On the 3DS savegames are stored much like on the DS, that is on a FLASH chip in the gamecart. On the DS these savegames were stored in plaintext but on the 3DS a layer of encryption was added. This is highly likely a streamcipher, as the contents of several savegames exhibit the odd behaviour that xor-ing certain parts of the savegame together will result in the plaintext appearing.+ + + +
→暗号化方式
====セーブデータについて====
====セーブデータについて====
=== 暗号化方式 ===
=== 暗号化方式 ===
3DSのセーブデータはゲームカートにまさにDSのそれと同じように保存されています。
DSではこのようなセーブデータはそのまま保存されていましたが、3DSにおいては暗号化して保存する仕組みが加わりました。
これはとても に似ています。
This is highly likely a streamcipher, as the contents of several savegames exhibit the odd behaviour that xor-ing certain parts of the savegame together will result in the plaintext appearing.
The reason this works is because the streamcipher used has a period of 512 bytes. That is to say, it will repeat the same keystream after 512 bytes. The way you encrypt with a streamcipher is you XOR your data with the keystream as it is produced. Unfortunately, if your streamcipher repeats and you are encrypting a known plaintext (in our case, zeroes) you are basically giving away your valuable keystream.
The reason this works is because the streamcipher used has a period of 512 bytes. That is to say, it will repeat the same keystream after 512 bytes. The way you encrypt with a streamcipher is you XOR your data with the keystream as it is produced. Unfortunately, if your streamcipher repeats and you are encrypting a known plaintext (in our case, zeroes) you are basically giving away your valuable keystream.