Method and apparatus for communicating scrambled digital data

Abstract

[A copy prevention method and apparatus of a digital magnetic recording / reproducing system performs the copy prevention function by encoding to insert a marker involving copy prevention function information and executing the function and allows a program supplier to realize a desired copy prevention function of various patterns, in which the marker formed by a control word for scrambling audio and video bit straps and copy prevention information for preventing an illegal copy is encrypted by an encoded key to be multiplexed with the audio and video bit strips scrambled by the control word. The marker transmitted is detected from the bit strips to be decrypted and analyzed by the encoded key to determine whether the copy is permitted or not, so that the detected marker is updated to be recorded on a video tape and the control word is produced from the marker to perform the descrambling to supply the result to a monitor to be displayed. Thus, the program supplier selects the copy prevention function, and a separate format converting apparatus is not required since a field defined within a GA format is utilized while an existing DVCR is not need to be changed for performing the copy prevention function as the data amount to be recorded is not increased.] The method and apparatus for transmitting and / or recording digital data generates control data and initializes a scrambler based on the control data. Digital data is scrambled using the scrambler. A marker is formed including the control data and the scrambled digital data and the marker are transmitted or recorded as a packet. The packet includes a header, which includes the marker. When the scrambled digital data and the marker, as a packet, are received, the marker is detected and the control data is obtained from the marker. A descrambler is initialized based on the control data, and the scrambled digital data is descrambled using the descrambler.

Description

BACKGROUND OF THE INVENTION1. Field of the InventionThe present invention relates to a copy prevention method and apparatus of a digital .[.magnetic.]. recording / reproducing system, and more particularly to a copy prevention method and apparatus of a digital .[.magnetic.]. recording / reproducing system, wherein a marker .[.involving copy prevention function information and executing the function is coded and inserted to perform the copy prevention function and realize the copy prevention function of various patterns desired by a program supplier.]. .Iadd.includes control data for descrambling digital data.Iaddend..2. Description of the Prior ArtOne example of a conventional copy prevention method is described in U.S. Pat. No. 4,819,098, in which a signal inducing an interference to an automatic gain controller (AGC) circuit within a VCR is inserted to a video waveform to be recorded on a tape. When the tape is reproduced to display the signal on a television, the interference signal ...

AI Technical Summary

Problems solved by technology

However, when the reproduced signal is recorded by another VCR, i.e., when it is duplicated, the interference signal brings about .[.the.]. interference in the AGC circuit of the .Iadd.recording .Iaddend.VCR

However, in case of a high-definition image of the analog television (ATV), the copy is performed by means of a digital VCR rather than an analog VCR, so that it is difficult to employ the copy prevention method of the analog system.

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