k-time encryption for k-time licensing

We introduce the notion of a k-time license for digital content and a method for ensuring its security via a k-time encryption scheme. A k-times license is an agreement that legally allows the purchaser to use the licensed material at most k times. The digital content is only accessible through a provided application that decrypts and re-encrypts the content according to our k-time encryption scheme. The application must use secret keys during this process, a vulnerability since the application resides on the user´s PC or electronic device. To help heighten the level of security of our system, we also introduce the idea of hiding secret keys in the heuristic solutions of NP-hard problems and then further extend the security with some other well known methods.