Management system, management device, management method, program, and non-transitory computer-readable information recording medium

A management device that manages an identifier and secret information associated with each other, the management device comprising:

• an updater that updates the secret information;
• an extractor that extracts an old fragment and a new fragment, the old fragment being included in the secret information prior to an update but not included in the secret information subsequent to the update, the new fragment being not included in the secret information prior to the update but included in the secret information subsequent to the update;
• a sender that sends a notice that specifies the identifier, the old fragment, and the new fragment to another management device;
• a receiver that receives another notice from the another management device;
• and
• a warning issuer that warns, when other secret information managed in association with another identifier specified in the another notice includes another old fragment specified in the another notice but does not include another new fragment specified in the another notice, a user using the another identifier to correct the other secret information.

A management method executed by a management system that comprises a first management device and a second management device, the first management device managing a first identifier and first secret information associated with each other, the second management device managing the first identifier and second secret information associated with each other, the management method comprising:

• a first updating step of updating the first secret information, the first updating step being performed by the first management device;
• a first extracting step of extracting a first old fragment and a first new fragment, the first old fragment being included in the first secret information prior to an update but not included in the first secret information subsequent to the update, the first new fragment being not included in the first secret information prior to the update but included in the first secret information subsequent to the update, the first extracting step being performed by the first management device;
• a first sending step of sending a first notice that specifies the first identifier, the first old fragment, and the first new fragment to the second management device, the first sending step being performed by the first management device;
• a second receiving step of receiving the first notice from the first management device, the second receiving step being performed by the second management device;
• and
• a second warning step of warning a user using the first identifier to correct the second secret information when the second secret information includes the first old fragment specified in the first notice but does not include the first new fragment specified in the first notice, the second warning step being performed by the second management device.

A non-transitory computer-readable information recording medium that records a program causing a computer to function as a management device that manages an identifier and secret information associated with each other, the program causing the computer to function as:

• an updater that updates the secret information;
• an extractor that extracts an old fragment and a new fragment, the old fragment being included in the secret information prior to an update but not included in the secret information subsequent to the update, the new fragment being not included in the secret information prior to the update but included in the secret information subsequent to the update;
• a sender that sends a notice that specifies the identifier, the old fragment, and the new fragment to another management device;
• a receiver that receives another notice from the another management device;
• and
• a warning issuer that warns, when other secret information managed in association with another identifier specified in the another notice includes another old fragment specified in the another notice but does not include another new fragment specified in the another notice, a user using the another identifier to correct the other secret information.