Digital signal transmitting method, digital signal receiving apparatus, and recording medium and method

Abstract

A digital signal transmitting method, a digital signal receiving apparatus, and a recording medium which ensure the security of fee-charged software information. When an image providing predetermined services is transmitted, a band-compression coded digital video signal is given first-encryption processing and then the digital signal is further given encryption processing and transmitted. Therefore, double security can be added to the video signal and a digital signal transmitting method where its security is more firmly ensured can be realized.

What is claimed is:  
     
       1. A method for transmitting a digital signal, comprising the steps of: 
       band-compression coding a first digital signal and a second digital signal, each respective digital signal defining an image;  
       encrypting the band-compression coded first digital signal;  
       multiplexing the encrypted first digital signal and the band-compression coded second digital signal; and  
       encrypting the multiplexed first and second digital signals to form said digital signal for transmission.  
     
     
       2. The method according to  claim 1 , wherein the band-compression coded first digital signal is encrypted with a first encryption key, and the multiplexed first and second digital signals are encrypted with a second encryption key. 
     
     
       3. Apparatus for transmitting a digital signal, comprising: 
       means for band-compression coding a first digital signal and a second digital signal, each respective digital signal defining an image;  
       means for encrypting the band-compression coded first digital signal;  
       means for multiplexing the encrypting first digital signal and the band-compression coded second digital signal; and  
       means for encrypting the multiplexed first and second digital signals to form said digital signal for transmission.  
     
     
       4. Apparatus according to  claim 3 , wherein the band-compression coded first digital signal is encrypted with a first encryption key, and the multiplexed first and second digital signals are encrypted with a second encryption key. 
     
     
       5. Digital signal receiving apparatus for receiving a digital video signal formed by multiplexing an encrypted first digital signal and a band-compression coded second digital signal and by encrypting the multiplexed first and second digital signals, said digital video signal encrypted with a first and second encryption key and transmitted by a broadcasting station, comprising: 
       first-decryption means for decrypting said digital video signal encrypted with said first encryption key;  
       recording/reproducing means for recording the first-decrypted digital video signal on a recording medium and for reproducing the first-decrypted digital video signal from said recording medium; and  
       second-decryption means for decrypting the reproduced first-decrypted digital video signal encrypted with said second encryption key.  
     
     
       6. Apparatus according to  claim 5 , wherein said broadcasting station comprises means for multiplexing said first digital signal and said second digital signal having a predetermined image band-compression coded, and means for encrypting the multiplexed first and second digital signals. 
     
     
       7. Apparatus according to  claim 5 , wherein during variable speed reproduction, and recording/reproducing means reproduces a variable-speed reproduction image defined by said digital video signal. 
     
     
       8. Apparatus according to  claim 5 , further comprising means for providing access to a plurality of management stations forming a billing system for processing billing information corresponding to predetermined services supplied by said digital video signal. 
     
     
       9. A recording medium comprising data recorded thereon, said data defined by a digital video signal formed by multiplexing an encrypted first digital signal and a band-compression coded second digital signal and by encrypting the multiplexed first and second digital signals. 
     
     
       10. A method for transmitting a digital transmission signal, comprising the steps of: 
       
         providing a first digital signal and a second digital signal, wherein the first digital signal is digital software data for a digital software distribution service;  
       
       
         encrypting the first digital signal with a first encryption key; wherein said digital software data is to be stored on a storage medium at a receiver side in an encrypted form encrypted with the first encryption key to secure the stored digital software data;  
       
       
         multiplexing the encrypted first digital signal and the second digital signal; and  
       
       
         encrypting the multiplexed digital signals with a second encryption key to form said digital transmission signal and to secure the digital transmission signal. 
       
     
     
       11. The method according to  claim 10 , further comprising: 
       
         charging a software fee to a user when said encrypted digital software data is reproduced from said storage medium at said receiver side and decrypted with a decryption key corresponding to said first encryption key at said receiver side. 
       
     
     
       12. The method according to  claim 10 , wherein 
       
         said digital software data is one of video software, music software and game software. 
       
     
     
       13. A method for transmitting a digital transmission signal, comprising the steps of: 
       
         providing a digital signal, wherein the digital signal is digital software data for a digital software distribution service;  
       
       
         encrypting the digital signal with a first encryption key; wherein said digital software data is to be stored on a storage medium at a receiver side in an encrypted form encrypted with the first encryption key to secure the stored digital software data;  
       
       
         multiplexing with other signals said encrypted digital signal encrypted with said first encryption key; and  
       
       
         encrypting the encrypted digital signal with a second encryption key to form said digital transmission signal and to secure the digital transmission signal. 
       
     
     
       14. A method for transmitting a digital transmission signal, comprising the steps of: 
       
         providing a digital signal, wherein the digital signal is digital software data for a digital software distribution service;  
       
       
         encrypting the digital signal with a first encryption key;  
       
       
         encrypting the encrypted digital signal with a second encryption key to form said digital transmission signal and to secure the digital transmission signal; and  
       
       
         charging a software fee to a user when said encrypted digital software data is reproduced from said storage medium at said receiver side and decrypted with a decryption key corresponding to said first encryption key at said receiver side;  
       
       
         wherein said digital software data is to be stored on a storage medium at a receiver side in an encrypted form encrypted with the first encryption key to secure the stored digital software data. 
       
     
     
       15. A method for transmitting a digital transmission signal, comprising the steps of: 
       
         providing a digital signal, wherein the digital signal is digital software data for a digital software distribution service;  
       
       
         encrypting the digital signal with a first encryption key; wherein said digital software data is to be stored on a storage medium at a receiver side in an encrypted form encrypted with the first encryption key to secure the stored digital software data; and  
       
       
         encrypting the encrypted digital signal with a second encryption key to form said digital transmission signal and to secure the digital transmission signal;  
       
       
         wherein said digital software data is one of video software, music software and game software. 
       
     
     
       16. Digital transmission apparatus for transmitting a digital transmission signal, comprising: 
       
         means for providing a first digital signal and a second digital signal, wherein the fist digital signal is digital software data for a digital software distribution service;  
       
       
         a first encryption circuit for encrypting the first digital signal with a first encryption key; wherein said digital software data is to be stored on a storage medium at a receiver side in an encrypted form encrypted with the first encryption key to secure the stored digital software data;  
       
       
         a multiplexer for multiplexing the encrypted first digital signal and the second digital signal; and  
       
       
         a second encryption circuit for encrypting the multiplexed digital signals with a second encryption key to form said digital transmission signal and to secure the digital transmission signal. 
       
     
     
       17. Digital signal receiving apparatus for receiving a digital transmission signal formed by encrypting a digital signal with a first encryption key and by encrypting the encrypted digital signal with a second encryption key to secure the digital transmission signal, wherein the digital signal is digital software data for a digital software distribution service, said digital signal receiving apparatus comprising: 
       
         a decryption circuit for decrypting said digital transmission signal with a second decryption key corresponding to said second encryption key;  
       
       
         an extracting circuit for extracting said digital signal in an encrypted form, the extracted digital signal having been encrypted with said first encryption key;  
       
       
         an outputting circuit for outputting the extracted digital signal to a recording/reproducing circuit which is connected via a digital bus or provided in the digital signal receiving apparatus in order to record the extracted digital signal on a storage medium in an encrypted form; and  
       
       
         a communication circuit for communicating billing information with a billing center, wherein a software fee is charged to a user where said recorded digital signal is reproduced from said storage medium and decrypted with a first decryption key corresponding to said first encryption key. 
       
     
     
       18. A method for receiving a digital transmission signal formed by encrypting a digital signal with a first encryption key and by encrypting the encrypted digital signal with a second encryption key to secure the digital transmission signal, wherein the digital transmission signal is digital software data for a digital software distribution service, said method comprising the steps of: 
       
         decrypting said digital transmission signal with a second decryption key corresponding to said second encryption key;  
       
       
         extracting said digital signal in an encrypted form, the extracted digital signal having been encrypted with said first encryption key;  
       
       
         outputting the extracted digital signal to a recording/reproducing circuit which is connected via a digital bus or provided in a digital receiving apparatus in order to record the extracted digital signal on a storage medium in an encrypted form; and  
       
       
         communicating billing information with a billing center, wherein a software fee is charged to a user when said recorded digital signal is reproduced from said storage medium and decrypted with a first decryption key corresponding to said first encryption key. 
       
     
     
       19. A method of transmitting a digital signal, the method comprising the steps of: 
       
         compressing a first digital signal and a second digital signal;  
       
         encrypting said compressed first digital signal with a first encryption key  ( Km ) ;    
       
         multiplexing the encrypted compressed first digital signal and compressed second digital signal;  
       
         encrypting the multiplexed first and second digital signals with a second encryption key  ( Ks ) ;    
       
         receiving an inquiry to reproduce said first digital signal stored on a recording medium of a receiver;  
       
       
         confirming registration of a subscriber who owns said receiver in response to said inquiry;  
       
       
         performing a billing processing if said registration is confirmed; and  
       
         transmitting said first encryption key  ( Km )  to said receiver after said billing processing is performed.   
     
     
       20. The method according to  claim 19 , further comprising: 
         encrypting said second encryption key  ( Ks );  
         wherein said multiplexing step multiplexes said first digital signal, second digital signal and said encrypted second encryption key  ( E ( Ks )) .   
     
     
       21. The method according to  claim 19 , further comprising: 
         encrypting said first encryption key  ( Km ) ;    
         wherein said transmitting step transmits said encrypted first encryption key  ( E ( Km ))  to said receiver.   
     
     
       22. The method according to  claim 19 , wherein said receiving step receives said inquiry via telephone line. 
     
     
       23. The method according to  claim 22 , wherein said transmitting step transmits said first encryption key ( Km )  via telephone line.   
     
     
       24. Apparatus for transmitting a digital signal, the apparatus comprising: 
       
         means for compressing a first digital signal and a second digital signal;  
       
         means for encrypting said compressed first digital signal with a first encryption key  ( Km ) ;    
       
         means for multiplexing the encrypted compressed first digital signal and compressed second digital signal;  
       
         means for encrypting the multiplexed first and second digital signals with a second encryption key  ( Ks ) ;    
       
         means for receiving an inquiry to reproduce said first digital signal stored on a recording medium of a receiver;  
       
       
         means for confirming registration of a subscriber who owns said receiver in response to said inquiry;  
       
       
         means for performing a billing processing if said registration is confirmed; and  
       
         means for transmitting said first encryption key  ( Km )  to said receiver after said billing processing is performed.   
     
     
       25. Apparatus according to  claim 24 , further comprising: 
         means for encrypting said second encryption key  ( Ks ) ;    
         wherein said multiplexing means multiplexes said first digital signal, second digital signal and said encrypted second encryption key  ( E ( Ks )) .   
     
     
       26. Apparatus according to  claim 24 , further comprising: 
         means for encrypting said first encryption key  ( Km ) ;    
         wherein said transmitting means transmits said encrypted first encryption key  ( E ( Km ))  to said receiver.   
     
     
       27. Apparatus according to  claim 24 , wherein said receiving means receives said inquiry via telephone line. 
     
     
       28. Apparatus according to  claim 27 , wherein said transmitting means transmits said first encryption key ( Km )  via telephone line.