| 摘要 |
PURPOSE:To prevent an unauthorized use by stealing of calling time information by ciphering a pass word with the information which is the intrinsic information at the time of inputting of the pass word and can be copossessed by plural devices as a ciphering key. CONSTITUTION:The pass word is ciphered with the information which is the intrinsic information at the time of inputting of the pass word and can be copossessed by the plural devices as the ciphering key. Namely, the pass word is ciphered by using the present time information as the ciphering key. The chiphering function when the ciphering key is designated as k and declarative sentence as p is specified to f(k,p). The ciphering sentence y=(k, p) is calculated in accordance with the ciphering function from the pass word p stored in a memory 7 and the present time k and the sentence is stored in a memory 5. Even if a person who attempts to make the unauthorized use of the electronic computer steals the calling time information of a normal utilizer, he is unable to know the pass word and since the effective ciphering key changes momentarily at the point of this time, the unauthorized use of the electronic computer is prevented. |
