| 摘要 |
An integrated, modular computer program system provides for the encryption and decryption of files utilizing conventional encryption algorithms and a relational key generated by the system. The computer program system also generates a series of labels that are encrypted and appended as a trailer to the encrypted message. The encrypted labels provide a history behind the particular encryption and they can be individually selected, separated, and decrypted from the total file. A rule based expert system is utilized as an intelligent label selection system to minimize message sensitivity. An access control module permits a user with a preassigned passphrase to have access to the encryption or decryption portion of the program by comparing a generated vector or key with a partially decrypted version of a second vector or key stored on a portable storage medium such as a floppy disk. If successful, the access control module creates a main key that is then used throughout the remainder of the program to encrypt or decrypt the labels. Part of the encryption or decryption process utilizes an internal, reproducible, but not reversible scrambling subroutine in which the bytes of an initializing vector are successively Exclusive ORed with one another and then the result concatenated to the initializing vector until all of the bytes have been so treated, and then the process repeated an integral number of times depending upon an input variable called a spinup number.
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