Method for preventing copying of digital video disks

Claim 1

A method for securely storing a series of frames of analog information which occur at a synchronous rate comprising: generating an analog noise signal; sampling said analog noise signal at said synchronous rate to produce a sample each frame; combining each sampled noise signal with said analog information signal of each frame to produce a combined signal; digitizing said combined signal; deriving a digital representation of said sampled analog noise signal; encrypting said digitized combined signal; and creating a plurality of frames of said encrypted digitized signal, each frame having a header with a frame identification field and said digital representation of said sampled noise signal; and storing said plurality of frames of said encrypted digitized signal on a data storage medium.

Claim 2

A method for securely storing a series of frames of analog information which occur at a synchronous rate comprising: generating an analog noise signal; sampling said analog noise signal at said synchronous rate to produce a sample each frame; combining each sampled noise signal with said analog information signal of each frame to produce a combined signal; digitizing said combined signal; deriving a digital representation of said sampled analog noise signal; encrypting said digitized combined signal; and creating a plurality of frames of said encrypted digitized signal, each frame having a header with a frame identification field and said digital representation of said sampled noise signal; and storing said plurality of frames of said encrypted digitized signal on a data storage medium.

Claim 10

A method for recovering analog information from a data medium comprising: reading digital data stored as frames on said data medium; deriving a key from data contained in each frame on said data medium derived from a noise component of said digital data; decrypting said digital data with said key; converting said digital data to an analog signal; and combining said key derived from a noise component with said analog signal to remove noise contained in said analog signal.

Claim 11

A method for recovering analog information from a data medium comprising: reading digital data stored as frames on said data medium; deriving a key from data contained in each frame on said data medium derived from a noise component of said digital data; decrypting said digital data with said key; converting said digital data to an analog signal; and combining said key derived from a noise component with said analog signal to remove noise contained in said analog signal.

Claim 14

An apparatus for securely storing analog information as occurring in frames at a synchronous rate comprising: a source of analog video signals comprising a synchronous sequence of frames; a sample and hold circuit, connected to operate in synchronism with said analog signal, said sample and hold circuit being connected to a noise generator for providing a sample of noise for each frame of the video signal; means for combining the value of noise derived from said sample and hold circuit with each frame of said analog video signal; means for converting said combined analog video signal and sample of noise signal to a digital signal; means for converting said sample of noise signal into a digital encryption key; means for encrypting said combined video signal and noise signal with said key forming a frame of encrypted data; means for inserting a frame number and a value of said key in a header of a frame of said encrypted data; and means for storing each of said frames on the medium.

Claim 15

An apparatus for securely storing analog information as occurring in frames at a synchronous rate comprising: a source of analog video signals comprising a synchronous sequence of frames; a sample and hold circuit, connected to operate in synchronism with said analog signal, said sample and hold circuit being connected to a noise generator for providing a sample of noise for each frame of the video signal; means for combining the value of noise derived from said sample and hold circuit with each frame of said analog video signal; means for converting said combined analog video signal and sample of noise signal to a digital signal; means for converting said sample of noise signal into a digital encryption key; means for encrypting said combined video signal and noise signal with said key forming a frame of encrypted data; means for inserting a frame number and a value of said key in a header of a frame of said encrypted data; and means for storing each of said frames on the medium.

Claim 17

A system for decrypting frames of encrypted video information stored on a recording medium comprising: a reader circuit for reading each frame of stored video signals; a decoder for recovering from a header on each read frame an encrypted key, and frame number; means for deriving a decyrption key from said encrypted key and frame number; means for decrypting information stored within said frame containing said encryption key with said decryption key; means for converting said decryption key into an analog voltage; means for converting said decrypted information into an analog voltage; and means for combining said analog voltages to produce an analog video signal.

Claim 18

A system for decrypting frames of encrypted video information stored on a recording medium comprising: a reader circuit for reading each frame of stored video signals; a decoder for recovering from a header on each read frame an encrypted key, and frame number; means for deriving a decyrption key from said encrypted key and frame number; means for decrypting information stored within said frame containing said encryption key with said decryption key; means for converting said decryption key into an analog voltage; means for converting said decrypted information into an analog voltage; and means for combining said analog voltages to produce an analog video signal.