Fujitsu Corporation

Toshiyuki Ohta

Noboru Kobayashi

Naoji Fujino

Toshiaki Nobumoto

Miki Murakawa

Kaoru Chujo

Tomonobu Takashima

Mitsuru Tsuboi

Nobuhide Eguchi

Yutaka Moriyama

Maiko Hirahara

Kazunari Hirakawa

A system and method is provided for easily detecting a fraudulent user who attempts to obtain authentication using voice reproduced by a reproducer. A personal computer is provided with an audio data obtaining portion for picking up ambient sound around a person as a target of user authentication using voice authentication technology during a period before the person utters, and a fraud determination portion for calculating an intensity level showing intensity of the picked-up ambient sound per predetermined time for each of sections into which the period is divided and for determining that the person is a fraudulent user who attempts to obtain authentication using reproduced voice, when, of two of the calculated intensity levels, the intensity level of the later section is larger than a sum of the intensity level of the earlier section and a predetermined value.

User authentication system, fraudulent user determination method and computer program product

A coded frame synchronization method for decoding coded information sent every frame includes the steps of: (a) receiving a coded frame having error detection or correction codes, each of which is provided every predetermined number of bits, error detection or correction codes being added to the coded frame in accordance with a predetermined pattern; (b) pulling the coded frame in synchronization by performing an error detection process every predetermined number of bits to be compared with results of the error detection process and thus detecting a phase of the error detection or correction codes; and (c) recognizing a leading end of the coded frame on the basis of the phase of the error detection or correction codes.

Coded frame synchronizing method and circuit

An apparatus synchronizes a voice coder and a voice decoder which are of the vector-coding type in order to prevent a false synchronization even when a signal having the same period as a string of synchronizing bits is inputted. A noise component adding unit adds a noise component to an input voice signal. Therefore, even if the input voice signal has the same period as that of a string of synchronizing bits and is completely periodic, the periodicity of the input voice signal is lost by the added noise component. Based on the input voice signal which is no longer periodic, a vector-coding unit, a quantizing signal vector generating unit, and a code book index transmitting unit generate code book indexes and transmit the generated code book indexes to a voice decoder. Therefore, the voice decoder is prevented from developing a false synchronization.

Apparatus for synchronizing a voice coder and a voice decoder of a

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Fukuoka, Japan

Toshiyuki Ohta