| 摘要 |
An objective of the present invention is to obtain a mutual authentication method in which mutual authentication is carried out securely and conveniently. In order to achieve the above objective, in the mutual authentication process, a private key K<SUB>0</SUB>, being an initial value, is stored in a client and a server (Pc 0 , Ps 0 ). The client generates a random number R, calculates secret data C and authentication data A, and transmits the data items to the server (Pc 1 ). The server receives the authentication data A and the secret data C from the client, and generates a random number Q, calculates secret data S, and authentication data B and returns the data items, as well as updating the private key K<SUB>0 </SUB>with a private key K<SUB>1 </SUB>(Ps 1 ). The client receives from the server the authentication data B and the secret data S, generates the random number R, calculates secret data C<SUB>2</SUB>, authentication data A<SUB>2</SUB>, and returns the data items to the server, and updates the private key K<SUB>0 </SUB>with the private key K<SUB>1</SUB>(Pc 2 ). The client and the server check whether or not validity is established (Ps<SUB>m+1</SUB>, Pc<SUB>m+1</SUB>). Further in the authentication method above, there is a method for generating a onetime ID, assuming that the onetime ID is identification information usable just one time in the authentication between a plurality of devices or application. In each of the devices or applications which carries out the authentication, a variable shared key which changes per predefined communication unit requiring the authentication is generated, a function value of one-way function is obtained in which the variable shared key is used as an argument, a onetime ID hard to tap and superior in security is generated based on the function value, and the onetime ID is utilized.
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