Cryptography – Cryptanalysis
Patent
1995-12-20
1998-05-12
Cangialosi, Salvatore
Cryptography
Cryptanalysis
380 21, H04L 916
Patent
active
057518050
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a system for protecting data such as application software, OS software, etc.
BACKGROUND ART
At present, duplication of data such as application programs, OS software, utility programs, etc. by unauthorized persons is an everyday affair, and no effective countermeasure has yet been devised against unauthorized use of such illegally duplicated programs and software.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to solve the above-mentioned defect inherent in the prior art and provide a data-protecting system which permits an authorized user to use a predetermined data, which could include software, in an ordinary manner and to easily but effectively prevent unauthorized users from using the data.
That is, the present invention is concerned with a data-protecting system in which a center, for example a vender of data, prepares a special algorithm, i.e., a center algorithm which is secretly held by the center only. The center then prepares a secret algorithm exclusively for the data and for the user by applying the center algorithm to the data, which can include software, for each data to be used by an individual user, and applying the user identifier. The secret algorithm is supplied to the user and to the data or software supplier, and the data or software supplier prepares the shared encryption key used between the data or software supplier and the user relying upon the user identifier and the secret algorithm of the data or software that is supplied, and encrypts part or all of the data or software that is to be supplied directly or indirectly based upon the encryption key, and then supplies it to the user. The user then prepares the shared encryption key used between the data or software supplier and the user, based upon the data or software identifier that is supplied, and his own secret algorithm, and decrypts the encrypted software directly or indirectly.
BRIEF DESCRIPTION OF DRAWINGS
FIGS. 1 to 3 are diagrams illustrating a method of embodying the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
In the following embodiment, software is referred to as the object to be protected. However, as mentioned above, any data including software can be protected, by the present invention.
According to the present invention as described above, there is realized a software-protecting system in which a center prepares a special algorithm or a center algorithm which is secretly held by the center only. The center prepares a secret algorithm exclusively used for the software and for the user by applying the center algorithm to the software identifier and the user identifier which are inherent to the software and the user, respectively, and are already known to the public and are used without any substantial change. The secret algorithm is supplied to the user and to the software supplier, and then when it happens that the software supplier must supply software to the user, the software supplier prepares a shared encryption key inherent to both the software that is to be supplied, and the user, by inputting the user identifier into the secret algorithm of the software that is to be supplied, and encrypts part or all of the software that is to be supplied directly or indirectly based on the encryption key and supplies it to the user. The user prepares the shared encryption key between the software that is supplied and the user, by inputting the software identifier that is supplied into his own secret algorithm and decrypts the encrypted software directly or indirectly. Accordingly, the authorized user is allowed to use the software through simple operation but other unauthorized users are not able to use it even though they may be able to copy it.
That is, according to the present invention, a center (such as, for example, an administration authority) is provided and secretly holds a center algorithm.
The center prepares a secret algorithm from the center algorithm, user and software identifiers (name, address, administration
REFERENCES:
patent: 4333207 (1982-06-01), Best
patent: 4484025 (1984-11-01), Ostermann et al.
patent: 5103476 (1992-04-01), Waite et al.
"Constitution of Simple One-way Algorithm," Matsumoto et al., Shingakugiho Co., IT89-23, Jul., 1989.
Matsumoto et al., "IC Card for Key Predistribution System and Cryptographic Communication", IEICE Spring National Convention Lecture Transactions, pp. 1-282, (1990).
Otsuki Kazunori
Watanabe Shinichirou
Cangialosi Salvatore
Kabushiki Kaisya Advance
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