US Patent 11956404 Authentication device and image forming apparatus

In an authentication device, a controller executes login when a user name and a password are entered through an operation device and the entered password is identical to one of a plurality of fixed passwords previously stored in association with the entered user name on an HDD. When the entered password is identical to none of the plurality of fixed passwords and any one of the plurality of fixed passwords satisfies a predetermined condition on similarity to the entered password, the controller inhibits an authentication based on the fixed password satisfying the predetermined condition from being made for a predetermined period.