The Nintendo 3DS uses AES encryption to protect its software. For Citra to run encrypted .3ds or .cia files, it needs access to the system's decryption keys.
The safest, most legal, and most reliable way to get citra_aes_keys.txt is to dump it from hardware you own. This process is called "key dumping." Citra Aes Keys.txt Download
In the dimly lit corner of a digital forum, a user named " The Nintendo 3DS uses AES encryption to protect its software
Obtaining aes_keys.txt involves a few steps, and users should proceed with caution and respect for copyright laws: fully compliant with Citra’s guidelines
: 100% safe, fully compliant with Citra’s guidelines, works with all games you own.