Abstract: A method of transmitting a media work such as a movie to a client is disclosed. The method includes (a) encrypting the work using a sequence of different keys corresponding to respective temporally spaced segments of the document, (b) transmitting software code containing an algorithm from a security server to the client, the algorithm having a result that is a function of the state of the client, (c) executing the code at the client and returning the result to the security server, (d) determining whether the result is indicative of an unmodified client. The method further includes (e) transmitting a segment from a server to the client, (f) securely streaming a key corresponding to the transmitted segment from a secure remote server to the client, (g) decrypting the segment using the obtained media key, (h) if step (d) indicates a modified client, preventing further keys from being transmitted, otherwise repeating steps (e) to (g) and repeating steps (b) to (d).

Abstract: The invention provides a method of transmitting a media work such as a movie to a client comprising the steps of (a) encrypting the work using a sequence of different keys corresponding to respective temporally spaced segments of the document, (b) transmitting software code containing an algorithm from a security server to the client, the algorithm having a result that is a function of the state of the client, (c) executing the code at the client and returning the result to the security server, (d) determining whether the result is indicative of an unmodified client, and further comprising the steps of: (e) transmitting a segment from a server to the client, (f) securely streaming a key corresponding to the transmitted segment from a secure remote server to the client, (g) decrypting the segment using the obtained media key, (h) if step (d) indicates a modified client, preventing further keys from being transmitted, otherwise repeating steps (e) to (g) and repeating steps (b) to (d).

Abstract: A method of and apparatus for transmitting data in systems such as computer networks, for example in client-server or peer-to-peer arrangements. Access to transmitted data received by a destination apparatus is limited by the provision of software code at the destination apparatus. The software code is arranged to produce a result which is a function of the state of the destination apparatus, and this result is used to access the data. The software code may be either transmitted to the destination apparatus, for example along with the data it is used to access or from a separate server, or may be generated at the destination apparatus. The method and apparatus is particularly applicable in the field of on-line gaming, wherein the transmitted data is encrypted gaming data and the result of the software code provides the access key to the encrypted data.

Abstract: The invention provides a method of transmitting a media work such as a movie to a client comprising the steps of (a) encrypting the work using a sequence of different keys corresponding to respective temporally spaced segments of the document, (b) transmitting software code containing an algorithm from a security server to the client, the algorithm having a result that is a function of the state of the client, (c) executing the code at the client and returning the result to the security server, (d) determining whether the result is indicative of an unmodified client, and further comprising the steps of: (e) transmitting a segment from a server to the client, (f) securely streaming a key corresponding to the transmitted segment from a secure remote server to the client, (g) decrypting the segment using the obtained media key, (h) if step (d) indicates a modified client, preventing further keys from being transmitted, otherwise repeating steps (e) to (g) and repeating steps (b) to (d).