| 摘要 |
<p>Encrypted digital information (e.g. a movie) is delivered over a computer network while controlling the number of times and the manner in which the information is used. A playback device (49) includes a decoder used to decrypt data, such as audio or video content, transmitted from a data distribution system or server (42). A key generator contained within the decoder generates a public key and a private key. The public key is transmitted to the server. The decoder receives from the server an encrypted key package including a decryption algorithm that includes instructions from a secret instruction set. The decoder also receives from the server an encrypted data package (58), wherein the data package is decryptable using the decryption algorithm. The decoder decrypts the encrypted key package using the private key to obtain a decrypted decryption algorithm which the decoder executes to decrypt the data package (55).</p> |
