Encrypt image in image

On this page, you can encrypt a picture inside another picture. You can decode it here . Unfortunately, images do not support transparency. The size of the encrypted image must be 3 times smaller than the size of the image in which it is encrypted, minus 4 pixels. The size of the image in which the picture will be encrypted must be more than 4 pixels. If these conditions are met, then if the encrypted picture does not fit into the image, then it will automatically be proportionally compressed to the desired size (maximum possible). Any encryption key can be used. For decryption, you need an encrypted picture and this key.