Medium, apparatus, and method related to encryption resultant information

Abstract

A disk-shaped recording medium includes a transparent substrate, and an optical recording layer formed on the transparent substrate. A light source emits light. An optical head is operative for applying the light to the optical recording layer from the light source via the transparent substrate, for focusing the light on the optical recording layer, and for reproducing information from the optical recording layer. A position detecting device is operative for detecting at least one of a pit depth and a physical position of information which has a first given relation with a specified address and which is recorded on the recording medium, and for generating first positional information representing at least one of the pit depth and the physical position. A previously-recorded secret code is reproduced from the recording medium. The secret code represents second positional information. The secret code is decoded into the second positional information. The second positional information represents at least one of a predetermined reference pit depth and a predetermined reference physical position. The first positional information and the second positional information are collated, and a check is made as to whether or not the first positional information and the second positional information are in a second given relation. When the first positional information and the second positional information are not in the second given relation, one of outputting of a reproduced signal of the recording medium, operation of a program stored in the recording medium, and decoding of the secret code is stopped.

1. A reproducing apparatus for reproducing signals from a recording medium in which first physical feature information indicative of a physical feature unique to said recording medium was recorded as ciphered information, said apparatus comprising:
 deciphering means for deciphering said ciphered information to obtain said first physical feature information;  
 detecting means for detecting and obtaining second physical feature information from said first physical feature information;  
 checking means for checking whether or not said first and second physical feature information have a specific relationship; and  
 means for stopping a specific operation when said checking means indicates that said first and second physical feature information do not have said specific relationship.  
 
     
     
       2. The reproducing apparatus as claimed in  claim 1 , wherein said specific operation comprises outputting information reproduced from said recording medium. 
     
     
       3. The reproducing apparatus as claimed in  claim 1 , wherein said specific operation comprises an operation under control of a program reproduced from said recording medium. 
     
     
       4. The reproducing apparatus as claimed in  claim 1 , wherein a public key cipher key is used, in said deciphering means, as a key for deciphering said ciphered information. 
     
     
       5. The reproducing apparatus as claimed in  claim 4 , wherein RSA cipher is used as said public key cipher key. 
     
     
       6. A reproducing apparatus for reproducing signals from a recording medium in which first physical feature information indicative of a physical feature unique to said recording medium was recorded as ciphered information, said method comprising the steps of:
 deciphering said ciphered information to obtain said first physical feature information;  
 detecting and obtaining second physical feature information from said first physical feature information;  
 checking whether or not said first and second physical feature information have a specific relationship; and  
 stopping a specific operation when said checking means indicates that said first and second physical feature information do not have said specific relationship.  
 
     
     
       7. The reproducing method as claimed in  claim 6 , wherein said specific operation comprises outputting information reproduced from said recording medium. 
     
     
       8. The reproducing method as claimed in  claim 6 , wherein said specific operation comprises an operation under control of a program reproduced from said recording medium. 
     
     
       9. The reproducing method as claimed in  claim 6 , further comprising a step of performing a specific display when said checking step indicates that said first and second physical feature information do not have said specific relationship. 
     
     
       10. The reproducing method as claimed in  claim 6 , wherein a public key cipher key is used, in said deciphering means, as a key for deciphering said ciphered information. 
     
     
       11. The reproducing apparatus as claimed in  claim 10 , wherein RSA cipher is used as said public key cipher key. 
     
     
       12. A reproducing apparatus for reproducing video signals recorded in a recording layer of an optical disk in such a manner that some pits are shifted in a direction normal to a longitudinal direction of a circular or spiral track comprising:
   disk driving means for rotating an optical disk;        an optical head for emitting a light beam and for receiving light from said optical disk to read information recorded in said disk in the form of pits;        tracking control means for effecting tracking control so that a light spot on said recording layer of said optical disk resulted from said light beam follows a series of pits on a track of said optical disk;        a tracking displacement amount detector unit for detecting displacement of said light spot in the direction normal to the longitudinal direction of the track;        a random number generator for generating random numbers;        reference value generating means for generating a reference value using an address obtained by decoding an output signal of said optical head and a random number from said random number generator;        a collation unit for generating collation information by collating said displacement obtained by said tracking displacement amount detector unit with said reference value;        reproducing means responsive to an output signal from said optical head for reproducing a video signal; and        an output/operation stopping section for stopping outputting of video information reproduced by said reproducing means to be externally outputted or for stopping reproducing operation of said reproducing means in accordance with said collation information.