Method and device for qualitative saving of digitized data
First Claim
1. A method for the qualitative protection of digital information recorded on a medium that can be erased or modified, said method comprising the steps of generating an encrypted computed signature representative of the information and of the identity of a signer holder of said information by means of of a computation algorithm according to computing parameters, and recording the signature on the same medium as said information, wherein said method further comprises the steps of recording said parameters for computing said signature on at least one inviolable medium, said computer algorithm being an algorithm for encryption and compression of the information to be protected on the basis of at least one secret key associated with said signer holder of the information, said algorithm comprising the steps of:
- initializing the creation of a sequence of random or pseudo-random numbers on several digits from said at least one secret key, said sequence of numbers comprising the same number Ci of terms as the number Ii of characters in the information to be protected,establishing term by term the scalar product P of the sequence of random numbers Ci and the information Ii to be protected, as defined by the equation;
##EQU3## applying modular reduction to the scalar product modulo p so as to define a number A=P modulo p in which p is a prime number comprising the same number of digits as there are characters in said at least one secret key or the signature, andapplying modular exponentiation to the number A so as to define a number S=A * ed modulo q in which q is another prime number comprising the same number of digits as there are characters in the at least one secret key or the signature and d is at least one of the digits of the at least one secret key, the number S constituting the encrypted signature.
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Abstract
An encrypted signature S representative of the information and of the identity of the holder of the information is established by means of a calculation algorithm for the encryption and the compression of the information to be saved. The signature S is recorded on the medium carrying the information forming the message M. The parameters for the calculation of the signature S, one or several secret keys, are recorded on at least one inviolable carrying medium. The application is to qualitative safeguarding and protection of data, on-line or not, in data bases.
140 Citations
27 Claims
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1. A method for the qualitative protection of digital information recorded on a medium that can be erased or modified, said method comprising the steps of generating an encrypted computed signature representative of the information and of the identity of a signer holder of said information by means of of a computation algorithm according to computing parameters, and recording the signature on the same medium as said information, wherein said method further comprises the steps of recording said parameters for computing said signature on at least one inviolable medium, said computer algorithm being an algorithm for encryption and compression of the information to be protected on the basis of at least one secret key associated with said signer holder of the information, said algorithm comprising the steps of:
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initializing the creation of a sequence of random or pseudo-random numbers on several digits from said at least one secret key, said sequence of numbers comprising the same number Ci of terms as the number Ii of characters in the information to be protected, establishing term by term the scalar product P of the sequence of random numbers Ci and the information Ii to be protected, as defined by the equation;
##EQU3## applying modular reduction to the scalar product modulo p so as to define a number A=P modulo p in which p is a prime number comprising the same number of digits as there are characters in said at least one secret key or the signature, andapplying modular exponentiation to the number A so as to define a number S=A * ed modulo q in which q is another prime number comprising the same number of digits as there are characters in the at least one secret key or the signature and d is at least one of the digits of the at least one secret key, the number S constituting the encrypted signature. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. Device for qualitative protection of digital information stored on a medium that can be erased or modified, comprising:
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a) first storage means in which are stored at least one key of a signer holder or an addressee of the information, b) second storage means in which is stored a program for computing at least one signature representative of the information and the identity of said signer holder of the digital information, c) means for computing said at least one signature and means for writing the computed at least one signature onto the same medium as the information to be protected, d) means for comparing the at least one signature written onto the same medium as the information with the at least one computed signature, e) means for validating use of the protected information when the at least one computed signature and the at least one signature recorded on the medium on which the information is recorded are identical, and f) peripheral means for input of data and peripheral means for output of data. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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Specification