초록 ▼

A copyright protection scheme downloads data from a server, typically over the World Wide Web to a client for presentation to a user. The downloaded data is cryptographically protected, by encryption and hashing. When displayed by the client, storing and copying functions are selectively disabled i

A copyright protection scheme downloads data from a server, typically over the World Wide Web to a client for presentation to a user. The downloaded data is cryptographically protected, by encryption and hashing. When displayed by the client, storing and copying functions are selectively disabled in respect of the data, in order to prevent unauthorized copying.

대표청구항 ▼

What is claimed is: 1. A method of protecting data sent from a server to a client, said method comprising: running a program portion at the client, the program portion generating and uploading to the server a request for access to data; cryptographically protecting the data; sending the cryptograp

What is claimed is: 1. A method of protecting data sent from a server to a client, said method comprising: running a program portion at the client, the program portion generating and uploading to the server a request for access to data; cryptographically protecting the data; sending the cryptographically protected data to the client; and after the running of the program portion has begun and under control of the program portion at the client, converting the cryptographically protected data to an unprotected form and selectively controlling access to copy or save functions at the client in respect of the data in its unprotected form. 2. A method as in claim 1 wherein cryptographically protecting the data comprises protecting the data by encryption. 3. A method as in claim 1 wherein cryptographically protecting the data comprises protecting the integrity of the data cryptographically. 4. A method as in claim 3 wherein the integrity of the data is achieved by hashing. 5. A method as in claim 1 including authenticating that the client is permitted to receive the data. 6. A method as in claim 1 including identifying the client to the server before the data are sent to the client. 7. A method as in claim 1 including: generating the program portion at a server, downloading the program portion to the client, and running the program portion on the client such that a request is uploaded to the server for a file containing the cryptographically protected data. 8. A method as in claim 7 wherein the program portion is generated in response to, and corresponds with, an earlier received request for access to the data. 9. A method of controlling access to data downloaded from a server computer to a client computer, said method comprising: downloading a protected copy of requested data from a server to a client; and before using said protected copy, running a program at the client so that after running the program at the client has begun at the client, the program serves to both: (a) unprotect the downloaded data thereby to provide access to an unprotected copy of the requested data, and (b) suppress client computer copy or save functions with respect to the unprotected copy of the requested data. 10. A method of controlling access to data sent from a server to a client, said method comprising: running a program portion at the client, the program portion generating and uploading to the server a request for access to data; cryptographically protecting the data; sending the cryptographically protected data to the client; and after access to the program portion is permitted and under control of the program portion, converting the cryptographically protected data to an unprotected form and restricting or preventing access to copy or save functions at the client in respect of the data in its unprotected form. 11. A method of controlling access to data downloaded from a server computer to a client computer, said method comprising: downloading a protected copy of requested data from a server to a client; and running a program at the client after access to the program is permitted to both: (a) unprotect the downloaded data thereby to provide access to an unprotected copy of the requested data, and (b) restrict or prevent client computer copy or save functions with respect to the unprotected copy of the requested data. 12. A method as in claim 1 wherein the data are sent to the client from the server through a network. 13. A server for providing access to data sets in a protected form, the server comprising: an input for receiving a request for access to a data set; protecting means for cryptographically protecting the requested data set; and generating means for generating a program portion for sending to the source of the access request, wherein said program portion is operable and after the program portion is permitted to run at the source of the access request, in use: to generate a request for access to the cryptographically protected data set; on receipt of the cryptographically protected data set, to convert it into an unprotected form; and to selectively control access to copy or save functions in respect of the data set when in said unprotected form. 14. A method as in claim 7 wherein the program portion includes data concerning a cryptographic key, and the method including using the key to render the downloaded cryptographically protected data into an unprotected form. 15. A method as in claim 1 wherein the server and the client each hold data corresponding to a cryptographic key and a machine identifier for uniquely identifying the client, the method including: sending a challenge to the client, such that it generates a signed response as a cryptographic function of the key and the machine identifier held therein, generating from the cryptographic key and machine identifier held associated with the server, a corresponding signed response as a cryptographic function of the key and the machine identifier, comparing the signed responses from the client and the server, and if they correspond, performing the cryptographic protection of the data with the key, and converting the cryptographically protected data into an unprotected form at the client with the key. 16. A method as in claim 1 wherein the data is steganographically marked. 17. A method as in claim 1 including registering the client with the server. 18. A method as in claim 1 including: determining a machine identifier of the client by analysing its hardware and/or its software configuration, transmitting the machine identifier to the server, combining the transmitted machine identifier with a cryptographic key to form a unique determinator for the client, transmitting the unique determinator to the client, to be stored therein for use subsequently in identifying the client to the server, to permit encypted data to be downloaded thereto from the server. 19. A method of protecting data downloaded from a server computer to a client computer, said method comprising: downloading a protected copy of requested data from a server to a client; and running a program at the client after access to the program is permitted to both: (a) unprotect the downloaded data thereby to provide access to an unprotected copy of the requested data, and (b) restrict or prevent client computer copy and save functions with respect to the unprotected copy of the requested data. 20. A method as in claim 19, wherein the program running at the client generates and uploads a request for data from the client to the server, and the protected copy of requested data is downloaded from the server to the client in response to the request. 21. A data storage medium storing copy protected data on the client received by a method according to claim 1. 22. A computer program carrier medium containing a computer program which are executable by a computer to perform method steps for implementing a server, the method steps comprising: receiving a request for access to a data set; cryptographically protecting the requested data set; and generating a program portion for sending to the source of the access request, wherein said program portion is operable and after the program portion is permitted to run at the source of the access request, in use: generating a request for access to the cryptographically protected data set; on receipt of the cryptographically protected data set, converting it into an unprotected form; and selectively controlling access to copy or save functions in respect of the data set when in said unprotected form. 23. A method of protecting data downloaded from a server computer to a client computer, said method comprising: downloading a protected copy of requested data from a server to a client; and running a program at the client so that after running the program at the client has begun at the client, the program serves to both: (a) unprotect the downloaded data thereby to provide access to an unprotected copy of the requested data, and (b) suppress client computer copy and save functions with respect to the unprotected copy of the requested data. 24. A method as in claim 23, wherein the program running at the client generates and uploads a request for data from the client to the server, and the protected copy of requested data is downloaded from the server to the client in response to the request. 25. A method of protecting data sent from a server to a client, said method comprising: running a program portion at the client, the program portion generating and uploading to the server a request for access to data; cryptographically protecting the data; sending the cryptographically protected data to the client; and after access to the program portion is permitted and under control of the program portion, converting the cryptographically protected data to an unprotected form and restricting or preventing access to copy or save functions at the client in respect of the data in its unprotected form. 26. A server for providing access to data sets in a protected form, the server comprising: an input for receiving a request for access to a data set; protecting means for cryptographically protecting the requested data set; and generating means for generating a program portion for sending to the source of the access request, wherein after access to the program portion is permitted and said program portion is operable, in use: to generate a request for access to the cryptographically protected data set; on receipt of the cryptographically protected data set, to convert it into an unprotected form; and to restrict or prevent access to copy or save functions in respect of the data set when in said unprotected form.