PC-based personal video recorder

A computer comprising:

• a memory;
• a tuner to tune a receiver for reception of video content;
• a content scrambler to scramble the video content;
• a memory access device to designate where the scrambled video content is stored in the memory and to retrieve the scrambled video content from the memory;
• a content descrambler to descramble the video content read from the memory;
• and
• a network connection to enable transmission of the video content to a remote decoder unit for decoding and display.

A video recorder card that is installable in a general-purpose computer, the video recorder card comprising:

• a tuner to tune a receiver for reception of video content;
• a key management processor to derive keys based on a local secret maintained on the video recorder card but kept unknown to the general-purpose computer;
• a content scrambler to encrypt the video content using ones of the keys derived by the key management processor;
• and
• a direct memory access (DMA) engine to direct storage of the encrypted video content in memory external of the video recorder card.

A method comprising:

• receiving a program in an original form;
• recording the program in memory of a general-purpose computer in a converted form that prevents the general-purpose computer from perceptibly displaying the recorded video content;
• and
• upon request by a viewer, retrieving the program from the memory and outputting the program in the original form for playback on a display device.

A method comprising:

• receiving content at a general-purpose computer;
• generating keys using a secret unknown to the general-purpose computer;
• encrypting the content using a first set of the keys;
• storing the encrypted content in memory of the general-purpose computer at selected memory addresses;
• encrypting the memory addresses using a second set of the keys;
• storing the encrypted memory addresses in the memory;
• encrypting the first and second sets of the keys;
• and
• storing the encrypted first and second sets of the keys in the memory.