To provide a document structure capable of preventing mixing of an ill-intentioned program regardless of operating environment of a computer.
An encapsulated document 64 is prepared by integrally encapsulating an encrypting public key 61 decoding encrypted digital information, a file 62 of an encrypted operation program decoded on the basis of the encrypting public key 61, and a file 63 of document information expressed and substantialized on the computer by the decoded operation program, as a single document. Thereby, the document 64 can be read even under environment different from a producer's computer. By imposing a limit by a security function on the operation program such that the file 62 of the operation program is decoded by a starting program 65 by use of the encrypting public key 61, the mixing of the ill-intentioned program is prevented to safely read the document.
KOIDE MASAMI
Naoto Koyama
Akira Kashiwagi
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