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Method for interdependently validating a digital content package and a corresponding digital license

  • US 6,973,444 B1
  • Filed: 01/13/2000
  • Issued: 12/06/2005
  • Est. Priority Date: 03/27/1999
  • Status: Expired due to Fees
First Claim
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1. A method for a device to interdependently validate a piece of digital content and a corresponding digital license for rendering the digital content, the digital content being encrypted, the encrypted digital content being decryptable according to a decryption key (KD) and being packaged in a digital content package, the digital content package being provided by a content provider having a public key (PU-C) and a private key (PR-C), the digital license being provided by a license provider having a public key (PU-L) and a private key (PR-L), the device having a public key (PU-D) and a private key (PR-D), the digital content package comprising:

  • the encrypted digital content; and

    the content provider public key (PU-C) encrypted with the decryption key (KD) and signed by the content provider private key (PR-C) (i.e., (KD (PU-C) S (PR-C)));

    the digital license comprising;

    the decryption key (KD) encrypted with the device public key (PU-D) (i.e., (PU-D (KD)));

    a digital signature from the license provider (without any attached certificate) based on (KD (DRL)) and (PU-D (KD)) and encrypted with the license provider private key (i.e., (S (PR-L))); and

    a certificate containing the license provider public key (PU-L) and signed by the content provider private key (PR-C) (i.e., (CERT (PU-L) S (PR-C)));

    the method comprising;

    obtaining (PU-D (KD)) from the license;

    applying (PR-D) to (PU-D (KD)) to produce (KD);

    obtaining (KD (PU-C) S (PR-C)) from the digital content package;

    applying (KD) to (KD (PU-C) S (PR-C)) to produce (PU-C);

    applying (PU-C) to (S (PR-C)) to validate (KD (PU-C) S (PR-C)), thereby validating the digital content package;

    obtaining (CERT (PU-L) S (PR-C)) from the license;

    applying (PU-C) to (CERT (PU-L) S (PR-C)) to validate (CERT (PU-L) S (PR-C)), thereby validating the content provider, and also to obtain (PU-L);

    obtaining (S (PR-L)) from the license; and

    applying (PU-L) to (S (PR-L)), thereby validating the license.

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