Decryption method and device, and access right authentication method and apparatus

A decryption device that decrypts a cipher text encrypted by RSA method, comprising:

• a first storage unit that stores a modulus n of a modulus exponentiation operation;
• a second storage unit that stores first decryption information d1;
• a cipher text input unit that inputs a cipher text C;
• an information input unit that inputs second decryption information d2;
• and
• an operation unit that performs the modulus exponentiation operation in which C is raised to a power, a product of d1 and a result of a predetermined operation on d2, modulo n and outputs a result of the operation.

A decryption device that decrypts a cipher text encrypted by RSA method, comprising:

• a first storage unit that stores a modulus n of a modulus exponentiation operation;
• a second storage unit that stores an Euler number of n (φ(n));
• a cipher text input unit that inputs a cipher text C;
• an information input unit that inputs decryption information d;
• a first operation unit that calculates an inverse number of d modulo φ(n);
• and
• a second operation unit that performs the modulus exponentiation operation in which C is raised to a power, a result of operation by the first operation unit, modulo n and outputs a result of the operation.

A decryption device that decrypts a cipher text encrypted by RSA method, comprising:

• a first storage unit that stores a modulus n of a modulus exponentiation operation;
• a first operation unit that calculates an Euler number of n (φ(n));
• a cipher text input unit that inputs a cipher text C;
• an information input unit that inputs decryption information d;
• a second operation unit that calculates an inverse number of d modulo φ(n);
• and
• a third operation unit that performs the modulus exponentiation operation in which C is raised to a power, a result of operation by the second operation unit, modulo n and outputs a result of the operation.

A decryption device that decrypts a cipher text encrypted by RSA method, comprising:

• a first storage unit that stores a modulus n of a modulus exponentiation operation;
• a second storage unit that stores an Euler number of n (φ(n));
• a cipher text input unit that inputs a cipher text C;
• an information input unit that inputs decryption information d;
• a first operation unit that calculates an inverse number of a result of a predetermined operation on d modulo φ(n);
• and
• a second operation unit that performs the modulus exponentiation operation in which C is raised to a power, a result of the operation by the first operation unit, modulo n and outputs a result of the operation.

A decryption device comprising:

• a storage unit that stores at least a piece of secret decryption information kept secret to the decryption device;
• a cipher text input unit that inputs a cipher text C;
• an information input unit that inputs at least a piece of open decryption information disclosed to the decryption device;
• and
• a decryption unit that decrypts C based on the secret decryption information and the open decryption information.

A decryption method comprising the steps of:

• storing at least a piece of secret decryption information kept secret to a decryption device;
• inputting a cipher text C;
• inputting at least a piece of open decryption information disclosed to the decryption device;
• and
• decrypting C based on the secret decryption information and the open decryption information.

A key generation device for an encryption method adopting a modulus exponentiation operation using an integer as a modulus, comprising:

• an operation unit that operates a non collision function;
• a composite number generation unit that generates a composite number;
• and
• a key generation unit that generates keys I, D and E used in the encryption method so that a product of D, E and a result of operation of the non collision function on I is congruent with 1 modulo an Euler number of the composite number.

A key generation device for an encryption method adopting a modulus exponentiation operation using an integer as a modulus, comprising:

• a redundancy providing unit that provides predetermined redundancy to a specific piece of information;
• a composite number generation unit that generates a composite number;
• and
• a key generation unit that generates keys I, D and E used in the encryption method, wherein I is generated by providing the predetermined redundancy to the specific piece of information by the redundancy providing unit and a product of I, D and E is congruent with 1 modulo an Euler number of the composite number.

An access right authentication apparatus that authenticates an access right of a user by verifying legitimacy of a response generated for proving the access right of the user, comprising:

• a first storage unit that stores challenging data;
• a second storage unit that stores user identifying information;
• a third storage unit that stores proof support information that is a result of a predetermined operation on security characteristic information and the user identifying information;
• a fourth storage unit that stores security required information;
• a response generation unit that generates a response by performing a predetermined operation on the challenging data, the user identifying information, the proof support information and the security required information;
• and
• a response verification unit that verifies the response is generated based on the security characteristic information and the security required information.

An access right authentication apparatus that authenticates a user's access right by verifying legitimacy of a response generated for proving the user's access right, comprising:

• a first storage unit that stores challenging data;
• a second storage unit that stores user identifying information;
• a third storage unit that stores proof support information generated by performing a first predetermined operation on security characteristic information and the user identifying information;
• a fourth storage unit that stores security required information;
• a fifth storage unit that stores security examination information;
• an examination unit that examines whether the security examination information has a specific relationship with a result of a second predetermined operation on the challenging data and the security required information;
• a response generation unit, when the examination unit determines that the security examination information has the specific relationship with the result of the second predetermined operation, that generates a response by performing a third predetermined operation on the challenging data, the user identifying information and the proof support information;
• and
• a response verification unit that verifies the response is generated based on the security characteristic information.

An access right authentication method for authenticating a user's access right by verifying legitimacy of a response generated for proving the user's access right, comprising the steps of:

• storing challenging data,
• storing user identifying information;
• storing proof support information generated by performing a predetermined operation on security characteristic information and the user identifying information;
• storing security required information;
• generating a response by performing a predetermined operation on the challenging data, the user identifying information, the proof support information and the security required information;
• and
• verifying that the response is generated based on the security characteristic information and the security required information.

An access right authentication method for authenticating a user's access right by verifying legitimacy of a response generated for proving the user's access right, comprising the steps of:

• storing challenging data,
• storing user identifying information;
• storing proof support information generated by performing a first predetermined operation on security characteristic information and the user identifying information;
• storing security required information;
• storing security examination information;
• examining whether the security examination information has a specific relationship with a result of a second predetermined operation on the challenging data and the security required information;
• when it is determined that the security examination information has the specific relationship with the result of the second predetermined operation in the examining step, generating a response by performing a third predetermined operation on the challenging data, the user identifying information and the proof support information;
• and
• verifying that the response is generated based on the security characteristic information.