SD title export: Difference between revisions

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The application itself (APP), and the title metadata (TMD) is encrypted with a console specific key. This means that Nintendo intended that these files can only be imported back into the same DSi.

While the banner, the public savegame, and several other ~~metadata blocks~~ are encrypted with a shared key, which means any DSi can inspect these parts of the file.

While the banner, the public savegame, and several other metablocks are encrypted with a shared key, which means any DSi can inspect these parts of the file.

= ES blocks =

An ES block, for lack of a better name, is a commonly used data encryption method on DSi by Nintendo.

It uses AES CCM to encrypt a maximum of 0x20000 bytes of data per time, and extends it with a 32 byte encrypted trail block at the end.

This trail block itself is encrypted with AES CTR, and contains the nonce for decryption and size of the ES block:

0000000: qq qq qq qq qq qq qq qq qq qq qq qq qq qq qq qq

0000010: xx nn nn nn nn nn nn nn nn nn nn nn nn yy yy yy

The counter used for decrypting the trail block is the last 16 bytes of the trailblock, with the first, 12th, 13th and 14th byte set to 0:

00 nn nn nn nn nn nn nn nn nn nn nn nn 00 00 00

After decrypting the trailblock, xx is always 0x3A, and yy is the size of the ES block (excluding the trail block). It is assumed that qq is a MAC (Message Authentication Code), used to verify the contents of the ES block after decryption, but this has not been verified yet.

= B4 block =

@@ Line 3: / Line 3: @@
 The application itself (APP), and the title metadata (TMD) is encrypted with a console specific key. This means that Nintendo intended that these files can only be imported back into the same DSi.
-While the banner, the public savegame, and several other metadata blocks are encrypted with a shared key, which means any DSi can inspect these parts of the file.
+While the banner, the public savegame, and several other metablocks are encrypted with a shared key, which means any DSi can inspect these parts of the file.
+= ES blocks =
+An ES block, for lack of a better name, is a commonly used data encryption method on DSi by Nintendo.
+It uses AES CCM to encrypt a maximum of 0x20000 bytes of data per time, and extends it with a 32 byte encrypted trail block at the end.
+This trail block itself is encrypted with AES CTR, and contains the nonce for decryption and size of the ES block:
+ 0000000: qq qq qq qq qq qq qq qq qq qq qq qq qq qq qq qq
+ 0000010: xx nn nn nn nn nn nn nn nn nn nn nn nn yy yy yy
+The counter used for decrypting the trail block is the last 16 bytes of the trailblock, with the first, 12th, 13th and 14th byte set to 0:
+nn nn nn nn nn nn nn nn nn nn nn nn 00 00 00
+After decrypting the trailblock, xx is always 0x3A, and yy is the size of the ES block (excluding the trail block). It is assumed that qq is a MAC (Message Authentication Code), used to verify the contents of the ES block after decryption, but this has not been verified yet.
 = B4 block =