Patent ID: 7610489

Claim:
A computer-implemented authentication device for authenticating an inputter based on an input password accepted from the inputter, the authentication device comprising: an input device configured for receiving a first part of the input password to be inputted, said input password comprising a series of characters; an output device configured for outputting confirmation information known to the inputter in advance when the first part of the received input password is valid, the confirmation information comprising a series of confirmation characters, each said confirmation character in one-to-one correspondence with a respective character of said series of characters of said first part of the input password and indicating to the inputter that the authentication device is valid; said input device configured for allowing a second part of the input password to be inputted; and, a computer device, in communication with said input and output devices, configured for determining that the inputter is valid when the first part of the input password and the second part of the input password are valid, the output device outputting, when the first part of the input password is invalid, information identical to the confirmation information corresponding to one or more character inputs of said first part of the input password determined valid, and outputs invalidity information different from the confirmation information in correspondence with other said one or more character inputs of said first part of the input password determined invalid, the output invalidity information being associated with both an identification of the inputter to be authenticated and, the corresponding other one or more character inputs of the first part of the input password determined invalid.