Changes

   keytype = SECURE;

   keytype = SECURE;

The insecure key is simply the first 16 bytes of the header. The secure key is constructed from a scrambled key pair, where one part is based on an 8-byte shared secret between all DSi's and an 8-byte expanded gamecode, and the other part is based on the first 16 bytes of the ARM9i SHA1 HMAC hash (0x350). The key scrambling method is currently unknown, and preventing the birth of a PC capable tool.

The insecure key is simply the first 16 bytes of the header. The secure key is constructed from a scrambled key pair, where one part is based on an 8-byte shared secret between all DSi's and an 8-byte expanded gamecode, and the other part is based on the first 16 bytes of the ARM9i SHA1 HMAC hash (0x350). The key pair is scrambled in an unknown way to form the final secure key.

 

It is likely that the insecure key is only used for a debug version of an application, since most card based and NAND based applications are using the secure key.