Sorry for the delayed reply.
@Grumpy_Mike - at first .WAV was an option, but now its fixed to an MP3 player.
You're trying to restrict the device to only play media files that come from you?
You're trying to ensure that no other players can play the media files you create?
Yes and Yes.
what lengths are you willing to go to to prevent people from overcoming your restrictions?
I'm willing to create a script (for encrypting in PC) and sketch that makes use of already existing cryptographic libraries.
I forgot to mention that the proprietary sound file should only be played with one dedicated player (for proof of concept).
e.g. a sound file (SOUND_1.*) can only be played with DEVICE_1 (arduino + mp3 player) and should not be usable/playable with DEVICE_2.
SOUND_1.* is the encrypted propietary sound file. DEVICE_1 and DEVICE_2 are the hardware projects.
I'm thinking that this maybe achieved by assigning IDs to the SOUND file before encryption, which is paired with only one DEVICE.