Image Number 10 for United States Patent #8132020.
The present invention relates to a system and method for digitally authenticating users both online and offline. In one embodiment, a hardware token assigned by a trusted token provider to the user is employed to ensure the identity of the user. In the online authentication, the token is adapted for generating an exposed key EK and a hidden key HK based on a noise code NC and a time code TC of the token, a space code SC of a service server, and an owner code OC of the user. A login session is initialized by entering a user identifier at the service server and the generated EK from a computing device. The service server computes an expose key CEK and a hidden key CHK based one an authentication license generated by the token provider. The service server authenticates the user if the CEK is same as the EK, and sends a response message encrypted the CHK to the computing device. Then, the user provides the HK to the computing device to decrypt the encrypted response message so as to access his/her account. In the offline authentication, the token is adapted for generating a license exposed key LEK used to render the encrypted digital content on an offline compliant device. The compliant device authenticates the user if a license exposed key computed by the compliant device based on a content license of which the user bought is same as LEK, so as to render the protected digital content after authentication.