| 主权项 |
1. A password management system comprising:
a character string conversion unit that converts an input character string to a character string different from the input character string using a predetermined arithmetic expression, the predetermined arithmetic expression being capable of giving a same converted result for a same character string and capable of converting a character string such that a plurality of original character string candidates exist for a converted character string, the predetermined arithmetic expression including, as a part, encryption arithmetic expression capable of converting an input character string to an encrypted character string that uniquely identifies the input character string; a password data storage unit that stores, for each user, a converted past password character string CPP that is a converted state of a past password character string PP of the user using the predetermined arithmetic expression and is different from the past password character string PP; and a strength determining unit that determines strength of a password, wherein upon accepting input of a new password character string NP with an instruction of changing a current password, the character string conversion unit converts the new password character string NP to a converted input character string CNP different from the new password character string NP using the predetermined arithmetic expression or the encryption arithmetic expression, and wherein the strength determining unit determine strength of the new password character string NP based on the converted input character string CNP and the converted past password character string CPP of the user stored in the password data storage unit. |
