3DSaveTool can be used to find the XOR key used for encryption and use it to encrypt/decrypt EEPROM savefiles of 3DS games.
Change log :
v0.2b
fixed a bug in the 0xFF block detection
v0.2
de/encrypting now starts at 0x1000
fixed a few new line errors in the usage info
when de/encrypting only 512byte blocks of 0xFF are skipped now
fixed a bug which would not de/encrypt the last 0x2000 bytes