It sounds like sort of a fit for an
asymmetric algorithm. You'd have to give the encryption systems a public key. The receivers would then decrypt the image with the private key.

This gets a bit complicated, because asymmetric encryption doesn't encrypt large datasets such as images. You'll have to create a random password and IV and then encrypt the image using those and a
symmetric algorithm. Then, use the asymmetric algorithm to encrypt the key and IV you randomly chose.

On the decryption end, do this in reverse: decrypt the key and IV using your asymmetric algorithm and private key, then decrypt the image data using the symmetric algorithm.

Darin R.