Video data bus communication system and method

Abstract

A video data communication system and method are disclosed which provides for the secure transmission of video data among devices connected to a video data bus. The video data is transmitted with address information corresponding to a particular device or, alternatively, video data is encrypted and transmitted on the data bus without address information.

1. A method for communicating video data via a data bus between a master device and a slave device which are each coupled to said bus, comprising the steps of:
 transmitting from said master device to said data bus a slave address of said slave device and a command;    generating, at said master device, a KEYCMD signal as a function of said command and a master security key;    receiving, at said slave device from said data bus, said slave address and said command and recognizing said slave address as corresponding to said slave device;    generating, at said slave device, an ACK signal as a function of said command and a slave security key;    transmitting from said slave device to said data bus a master address of said master device and said ACK signal;    receiving, at said master device from said data bus, said master address and said ACK signal and recognizing said master address as corresponding to said master device;    comparing said KEYCMD signal generated by said master device with said ACK signal received by said master device; and    executing a data transfer between said master device and said slave device if said KEYCMD signal corresponds to said ACK signal.    
     
     
       2. The method, according to  claim 1 , further comprising the step of:
 inhibiting a data transfer between said master device and said slave device if said KEYCMD signal does not correspond to said ACK signal.    
     
     
       3. The method, according to  claim 2 , wherein said data is unencrypted and encoded and wherein said step of inhibiting a data transfer comprises:
 transmitting said data from said slave device to said data bus; and    preventing said master device from decoding said data from said data bus.    
     
     
       4. The method, according to  claim 2 , wherein said step of inhibiting a data transfer comprises:
 preventing said master device from transmitting said data to said data bus.    
     
     
       5. The method, according to  claim 1 , wherein said master device is a receiver and said slave device is a peripheral device. 
     
     
       6. The method, according to  claim 5 , wherein said peripheral device is a display device. 
     
     
       7. The method, according to  claim 1 , wherein said master device is a peripheral device and said slave device is a receiver. 
     
     
       8. The method, according to  claim 1 , wherein said master device is a first peripheral device and said slave device is a second peripheral device. 
     
     
       9. The method, according to  claim 1 , wherein said slave device comprises means for decoding an unencrypted coded data. 
     
     
       10. The method, according to  claim 1 , wherein said step of executing a data transfer comprises:
 encrypting said data in said master device according to an encryption key; and    decrypting said data in said slave device according to said encryption key.    
     
     
       11. The method, according to  claim 10 , wherein said step of executing a data transfer further comprises:
 transmitting said slave address and said encryption key from said master device to said data bus; and    receiving said encryption key and said slave address at said slave device from said data bus and recognizing said slave address as corresponding to said slave device.    
     
     
       12. The method, according to  claim 10 , further comprising the step of:
 inhibiting a data transfer between said master device and said slave device if said KEYCMD signal does not correspond to said ACK signal.    
     
     
       13. The method, according to  claim 12 , wherein said step of inhibiting a data transfer comprises:
 preventing said master device from transmitting said data to said data bus.    
     
     
       14. The method, according to  claim 10 , wherein said master device is a receiver and said slave device is a peripheral device. 
     
     
       15. The method, according to  claim 14 , wherein said peripheral device is a display device. 
     
     
       16. The method, according to  claim 10 , wherein said master device is a peripheral device and said slave device is a receiver. 
     
     
       17. The method, according to  claim 10 , wherein said master device is a first peripheral device and said slave device is a second peripheral device. 
     
     
       18. The method, according to  claim 10 , wherein said slave device comprises means for decoding a decrypted coded data. 
     
     
       19. The method, according to  claim 1 , wherein said step of executing a data transfer comprises:
 encrypting said data in said slave device according to an encryption key; and    decrypting said data in said master device according to said encryption key.    
     
     
       20. The method, according to  claim 19 , wherein said step of executing a data transfer further comprises:
 transmitting said master address and said encryption key from said slave device to said data bus; and    receiving said master address and said encryption key from said data bus at said master device and recognizing said master address as corresponding to said master device.    
     
     
       21. The method, according to  claim 19 , further comprising the step of:
 inhibiting a data transfer between said master device and said slave device if said KEYCMD signal does not correspond to said ACK signal.    
     
     
       22. The method, according to  claim 21 , wherein said data is encrypted and encoded and wherein said step of inhibiting a data transfer comprises:
 transmitting said data from said slave device to said data bus; and    preventing said master device from decoding said data from said data bus.    
     
     
       23. The method, according to  claim 19 , wherein said master device is a receiver and said slave device is a peripheral device. 
     
     
       24. The method, according to  claim 23 , wherein said peripheral device is a display device. 
     
     
       25. The method, according to  claim 19 , wherein said master device is a peripheral device and said slave device is a receiver. 
     
     
       26. The method, according to  claim 19 , wherein said master device is a first peripheral device and said slave device is a second peripheral device. 
     
     
       27. The method, according to  claim 19 , wherein said slave device comprises means for decoding a decrypted coded data. 
     
     
       28. A system for communicating video data comprising:
 at least one master device having a master address;    at least one slave device having a slave address;    a data bus, coupled to said master device and to said slave device;    said master device including: 
 means for transmitting to said data bus said slave address and a command;  
 means for generating a KEYCMD signal as a function of said command and a master security key,  
 means for receiving from said data bus said master address and an ACK signal,  
 means for recognizing said master address as corresponding to said master device,  
 means for comparing said KEYCMD signal and said ACK signal, and  
 means for receiving said video data from said data bus if said KEYCMD signal corresponds to said ACK signal; and  
   said slave device including: 
 means for receiving from said data bus said slave address and said command,  
 means for recognizing said slave address as corresponding to said slave device,  
 means for generating said ACK signal as a function of said command and a slave security key, and  
 means for transmitting to said data bus said master address, said ACK signal, and said video data.  
   
     
     
       29. The system according to  claim 28 , wherein said master device further comprises means for inhibiting reception of said video data from said data bus if said KEYCMD signal does not correspond to said ACK signal. 
     
     
       30. The system according to  claim 29 , wherein said means for inhibiting includes a switch. 
     
     
       31. The system according to  claim 28 , wherein said master device is a receiver and said slave device is a peripheral device. 
     
     
       32. The system according to  claim 28 , wherein said master device is a peripheral device and said slave device is a receiver. 
     
     
       33. The system according to  claim 28 , wherein said master device is a first peripheral device and said slave device is a second peripheral device. 
     
     
       34. The system according to  claim 28 , wherein said video data is unencrypted and encoded and wherein said slave device comprises means for decoding said video data. 
     
     
       35. The system according to  claim 28 , wherein:
 said master device further includes means for decrypting said video data according to an encryption key; and    said slave device further includes means for encrypting said video data according to said encryption key.    
     
     
       36. The system according to  claim 35 , wherein:
 said master device further includes means for receiving said encryption key from said data bus; and    said slave device further includes means for transmitting said encryption key to said data bus.    
     
     
       37. A system for communicating video data comprising:
 at least one master device having a master address;    at least one slave device having a slave address;    a data bus, coupled to said master device and to said slave device;    said master device including: 
 means for transmitting to said data bus said slave address and a command,  
 means for generating a KEYCMD signal as a function of said command and a master security key,  
 means for receiving from said data bus and master address and an ACK signal,  
 means for recognizing said master address as corresponding to said master device,  
 means for comparing said KEYCMD signal and said ACK signal, and  
 means for transmitting to said data bus said video data if said KEYCMD signal corresponds to said ACK signal; and  
   said slave device including: 
 means for receiving from said data bus said slave address, said command and said video data,  
 means for recognizing said slave address as corresponding to said slave device,  
 means for generating said ACK signal as a function of said command and a slave security key, and  
 means for transmitting to said data bus said master address and said ACK signal.  
   
     
     
       38. The system according to  claim 37 , wherein said master device further includes means for inhibiting transmission of said video data to said data bus if said KEYCMD signal does not correspond to said ACK signal. 
     
     
       39. The system according to  claim 37 , wherein:
 said master device further includes means for encrypting said video data according to an encryption key; and    said slave device further includes means for decrypting said video data according to said encryption key.    
     
     
       40. The system according to  claim 39 , wherein:
 said master device further includes means for transmitting said encryption key to said data bus; and    said slave device further includes means for receiving said encryption key from said data bus.    
     
     
       41. An apparatus for receiving a scrambled compressed signal, comprising:
   an input for receiving said scrambled compressed signal;        a descrambler for descrambling said received signal;        an encryptor for encrypting said descrambled signal; and        controller for executing an authentication procedure between the apparatus and an other device via a data bus;        wherein said controller executes a data transfer of said encrypted signal to the other device via said data bus if said authentication procedure is successfully executed.     
     
     
       42. The apparatus of  claim 41 , wherein said controller transfers an encryption key, via said data bus to said other device, that is used by said encryptor. 
     
     
       43. The apparatus of  claim 41 , further comprising:
   a decoder for decoding said descrambler signal; and        a decryptor for decrypting a signal which is processed and transmitted from said other device, wherein said controller executes a data transfer of said processed signal to said decoder via said data bus if said authentication procedure is successively executed.     
     
     
       44. An apparatus for recording a compressed signal on a recording medium, comprising:
   a communication interface coupled to a data bus for receiving an encrypted compressed signal from another device connected to said data bus;        a decryptor for decrypting said received signal;        a recording circuit for recording said decrypted compressed signal on said recording medium;        a controller for executing via said data bus an authentication procedure between said apparatus and said another device, and for controlling said decryptor and said recording circuit;        wherein said controller initiates said decrypting and said recording of said received signal if said authentication procedure is successively executed.     
     
     
       45. The apparatus of  claim 44 , further comprising:
   a reproducing circuit for reproducing said recorded signal; and        an encryptor for encrypting said reproduced signal, wherein said controller executes said reproducing and encryption of said recorded signal if said authentication procedure is successfully executed, and the encrypted signal is transferred via said data bus to said another device connected to said data bus.     
     
     
       46. The apparatus of  claim 44 , wherein said controller receives an encryption key via said data bus, which is used in said encryptor, to said another device connected to said data bus. 
     
     
       47. An apparatus for reproducing a compressed signal recorded on a recording medium, comprising:
   a reproducing circuit for reproducing said signal recorded on said recording medium;        an encryptor for encrypting said reproduced signal;        a communication interface coupled to a data bus for transmitting said encrypted signal;        a controller for executing an authentication procedure via said data bus between said apparatus and another device connected to said data bus, and for controlling said reproducing circuit and encryptor;        wherein said controller executes said reproducing and encrypting of said recorded signal if said authentication procedure is successfully executed.     
     
     
       48. The apparatus of  claim 47 , wherein said controller transfers an encryption key via said data bus, which is used in said encryptor, to said another device connected to said data bus. 
     
     
       49. A method for communicating compressed data via a data bus between a first and a second device which are coupled together via said data bus, comprising the steps of:
   executing an authentication procedure between said first and second device;        transmitting encrypted compressed data from said first device to said second device via said data bus when said authentication procedure is successfully executed; and        receiving said encrypted compressed data at said second device.     
     
     
       50. The method of  claim 49 , further comprising the step of transmitting an encryption key which is used to encrypt the compressed data, via said data bus, from said first device to said second device. 
     
     
       51. A method for communicating compressed data via a data bus between a first and a second device which are coupled together via said data bus, comprising the steps of:
   executing an authentication procedure between said first and second device;        transmitting encrypted compressed data from said first device to said second device via said data bus; and        transmitting an encryption key which is used to encrypt said compressed data, from said first device to said second device via said data bus.     
     
     
       52. A method for communicating compressed data via a data bus between a first and a second device which are coupled together via said data bus, comprising the steps of:
   executing an authentication procedure between said first and second device;        receiving at said first device encrypted compressed data transmitted from said second device via said data bus when said authentication procedure is successfully executed; and        receiving at said first device an encryption key which is used to encrypt said compressed data, from said second device via said data bus.     
     
     
       53. A method for communicating data via data bus between a first and a second device which are coupled together via said data bus, comprising the steps of:
   receiving at said first device an encrypted data;        decrypting at said first device said received encrypted data;        re - encrypting at said first device said decrypted data; and        transmitting said encrypted data from said first device to said second device.     
     
     
       54. The method of  claim 53 , wherein said data is compressed. 
     
     
       55. The method of  claim 53 , further comprising the step of transmitting an encryption key from said first device to said second device via said data bus, the encryption key being used re- encrypt said decrypted data at said first device.   
     
     
       56. The method of  claim 53 , wherein re- encryption uses a different encryption scheme from an encryption scheme used to encrypt said received data.