I am exploring DRM technology now.
Forward lock and Combined delivery looks not secure, because hacker can catch midlet in the delivery phase (by PC for example).
But what about Separate delivery? It looks very protected. As I understood, MidLet should be delivered encrypted by AES. And AES key should be sended to the phone by o3.48 SMS. It looks absolutly protected. Am I right? Or separate delivery has any defect too?