To provide simpler method and device that do not use the conventional enciphering processing which is complicated and hard to use and in which there is also the possibility that 'pretense to be someone else' or the like is made, and that prevent ill use by leakage on a network by utilizing biological information having high reliability.

Simple and high security is realized in such a manner that an authentication requesting side and an authenticating side exchange a working key with which a simple operation such as bit rotation and bit inversion is applied to biological information data by focusing attention on the randomness of the biological information data.