Nintendo uses a system of "key slots" in the AES engine. Software running on the 3DS can request that the hardware engine decrypt data using a specific slot, but the software never sees the actual key value.
3DS games are encrypted, and emulators require a set of unique AES (Advanced Encryption Standard) keys to decrypt the game files (often .cia , .3ds , or .ncch formats). 3ds aes keys
: Instead of using a single "normal key," the system often combines two keys— KeyX and KeyY —through a hardware "keyscrambler" to generate the final key. Nintendo uses a system of "key slots" in the AES engine