Copy protection method and system for digital media
A copy protection method and a copy protection system are disclosed. The system includes a private key verifier receiving a media certificate that includes a private key identification of a compliant playing device and searching for an actual private key corresponding to the private key identification, an intermediate key decryptor receiving an encrypted intermediate key and decrypting the intermediate key with the actual private key, a media key decryptor obtaining an original media key by decrypting the decrypted intermediate key with a media identification; and a media data decryptor receiving an encrypted media data set and decrypting the media data set with the original media key. The method and system of the present invention are applicable to all types of digital media data, and it makes no assumption of any specific media properties. The primary goal of the present invention is to significantly reduce the possibility of making any illegal copies on any nonstandard equipment and is to restrict the media data transfers only to authorized entities.
1. A copy protection method for digital media, the method comprising:
(a) encrypting an original media data set with a symmetric algorithm corresponding to an original media key;
(b) generating an intermediate key by encrypting said original media key with a media identification;
(c) encrypting said intermediate key with a public key of a compliant playing device; and
(d) delivering said encrypted media data set, said encrypted intermediate key and a media certificate to said playing device, said media certificate including said media identification and a private key identification of said playing device, said private key identification generated by encrypting said media identification with said public key of said playing device, wherein said private key identification is used to recognize a valid private key among private keys stored in said playing device, and said media certificate is used to verify said valid private key.
2. The method of claim 1 , wherein said media identification and said public key are separately provided and are independent of each other.
3. The method of claim 2 , wherein said original media key and said intermediate key are encrypted with independent encipherment algorithms.
4. A copy protection system for digital media, the system comprising:
a media data encryptor configured to encrypt an original media data set with a symmetric algorithm corresponding to an original media key;
a media key encryptor configured to generate an intermediate key by encrypting said original media key with a media identification;
an intermediate key encryptor configured to encrypt said intermediate key with a public key of a compliant playing device; and
a deliverer configured to deliver said encrypted media data set, said encrypted intermediate key and a media certification to said playing device, said original media data set including a media certificate, said media certificate including a media identification and a private key identification of a compliant playing device, said private key identification generated by encrypting said media identification with said public key of said playing device, wherein said private key identification is used to recognize a valid private key among private keys stored in said playing device, and said media certificate is used to verify said valid private key.
5. The system of claim 4 , wherein said media identification and said public key are separately provide and are independent of each other.
6. The system of claim 5 , wherein said original media key and said intermediate key are encrypted with independent encipherment algorithms.