Licensing content for use on portable device

A computer-readable medium having stored thereon computer-executable instructions implementing a method in connection with a computing device having encrypted digital content and a corresponding digital license having a decryption key (KD) for decrypting the encrypted content, the license allowing the computing device to render the content thereon, the method for the computing device to issue a digital sub-license based on the license to a portable device communicatively coupled thereto, the sub-license for allowing the portable device to render the content thereon and having the decryption key (KD), the portable device having a digital device certificate including information on the portable device, the method comprising:

• the computing device receiving from the portable device a copy of the device certificate thereof;
• the computing device determining based on rules in the license and also based on the information on the portable device as set forth within the device certificate whether the computing device can in fact issue the sub-license to the portable device;
• and
• if the computing device can in fact issue the sub-license to the portable device, the computing device constructing such sub-license to include the decryption key (KD) and transmitting the constructed sub-license to the portable device.