| 摘要 |
A level of security is applied to an object file by selecting sections of the file for encryption, whilst leaving other portions of the file unencrypted. For large files of the order of 5 to 100 megabytes or above, the whole file can be "spoiled" to a potential hacker, since parts of the complete file are either missing, or are protected by encryption. The file can be distributed in various ways, for example electronically by data transfer over a communications network or on a physical storage media or any confirmation thereof. The file may be split into encrypted and unencrypted portions or any combination thereof and sent as a series of separate packages either physical, for example loaded on a DVD and/or as electronic transmitted data files. Reconstitution of the original data file requires decryption of the encrypted sections, and access to both the encrypted and the unencrypted portions. In the best mode implementation, decryption of the file is left as late as possible in a chain of computer entities, so as to be as close as possible to a point of delivery of the file content as possible. By only partially encrypting a file, a trade off of security against data processing power required for decryption can be applied. <IMAGE> |
