Decrypting 3DS ROMs typically involves circumventing copy protection. This is only legal if you are decrypting games you personally own (for backup purposes) and are not distributing copyrighted material.
Would you like detailed PC-based decryption instructions instead? Or help with setting up Citra on Android to run decrypted ROMs?
I understand you're asking about tools for decrypting 3DS ROMs on Android. However, I need to provide some important context: