Patent ID: 8706635
Filing Date: 2014-04-22
Classification: G06F,H04N

Abstract:
1. A method in connection with a piece of encrypted digital content, the method for a user to obtain a content key (CK) for decrypting the encrypted digital content, the method comprising: obtaining, by a first computing device, content encrypted with a content key, the content key encrypted with a public key of a licensor, and the public key of the licensor from a distributor's computing device; determining, by the first computing device, values including a public exponent e and modulus n from the public key of the licensor; selecting, by the first computing device, a value R; obscuring, by the first computing device, the content key encrypted with the public key of the licensor according to the public key of the licensor and the value R by computing Y using e and modulus n determined from the public key of the licensor, wherein Y is computed as Y=Re mod n, and multiplying the content key encrypted with the public key of the licensor by the computed Y to result in an obscured content key encrypted with the public key of the licensor; sending, by the first computing device, the obscured content key encrypted with the public key of the licensor Obs (PU-L(CK)) to the licensor's computing device; receiving, by the first computing device, obscured content key from the licensor's computing device, wherein the obscured content key is (R*CK) mod n and is derived from applying a private key of the licensor to the obscured content key encrypted with the public key of the licensor; obtaining, by the first computing device, the content key from the obscured content key by applying R to the obscured content key; and decrypting, by the first computing device, the content encrypted with the content key with the obtained content key.