| 摘要 |
PROBLEM TO BE SOLVED: To easily recover a password invalid state at the hand of user. SOLUTION: A card ID, which is known only by a provider, peculiar for a card is held in a storage means 11 and when the number of password collation errors exceeds a specified number, card unusable is set and reported to the user. When the user inputs a recovery request, a random number R is generated and temporarily stored. Then, the random number R is sent to the provider, the provider operates a specified function (Hash function, for example), with these card ID and random number R as parameters according to contact from the user and returns the result P to the card and inside the card, the specified function is operated by the card ID and the random number R as well. Then, the result is compared with the input P. When they are coincident, the number of times of collation errors is cleared and card unusable is set. |
