Patent ID: 7206943

Claim:
A method of using and storing a cryptography key in a display unit, comprising: retrieving a first encrypted key from anon-volatile memory incorporated in the display unit; generating a first decrypted key by decrypting the first encrypted key according to a first encryption protocol; receiving a plurality of pixel data elements encoded in a display signal in an encrypted form that represents an image; decrypting said encrypted plurality of pixel data elements using the first decrypted key; generating said plurality of pixel data elements based upon said decrypted plurality of pixel data elements; displaying said image on a display screen based on said decrypted plurality of pixel data elements; destroying the first encrypted key; receiving a second encrypted key from non-volatile memory that is different from the first encrypted key; generating a second encrypted key by decrypting the second encrypted key according to a second encryption protocol that is different from the first encryption protocol; decrypting a second encrypted plurality of pixel data elements using the second decrypted key; generating a second plurality of pixel data elements based upon said second decrypted plurality of pixel data elements; displaying said second decrypted plurality of pixel data elements.