Nippon Telegraph and Telephone Corporation

Fujitsu Corporation

Kabushiki Kaisha Meidensha

Masaru Matsubayashi

Masashi Tanaka

Yasushi Okano

Takuma Koyama

Takao Watanabe

Chikara Tsuchiya

Kazunari Matsumoto

Takashi Matsui

Mutsuo Hayashi

An authentication apparatus that performs authentication of a client terminal by challenge-response authentication, the authentication apparatus includes one or more computers each including a memory and a processor configured to: receive a challenge request from the client terminal; generate a challenge as to the challenge request; and transmit the challenge to the client terminal. The memory and the processor are configured to generate the challenge by one generating method out of a fixed generating method in which a challenge of a fixed value is generated, and a random generating method in which a challenge of a random value is generated, in accordance with a state of the authentication apparatus.

Authentication apparatus, authentication method and program for generating a challenge in accordance with a state of challenge-response authentication with a client terminal

Provided is a communication apparatus communicating with an external apparatus connected via a network, and the communication apparatus includes a processor and a memory storing program instructions that cause the processor to: calculate a communication interval of data communicated within the communication apparatus; determine whether to perform communication with the external apparatus based on whether the communication interval is within a range set in advance; and transmit, to the external apparatus, communication data including the communication interval determined to perform communication with the external apparatus, latter data in the communication interval, and a transition between former data and the latter data in the communication interval, so that traffic from an apparatus to outside is reduced while suppressing deterioration in detection accuracy of unauthorized communication.

Communication apparatus, external apparatus, communication system, communication method and program

A digital control system such as a digital temperature compensated crystal oscillator (DTCXO) system is arranged to offer superior oscillating performance with reduced size and cost. For example, to reduce the memory capacity, a memory 31 receives upper 6 bits of temperature data, and a decoder 32 calculates temperature compensation data from lower 4 bits and output data from the memory (FIGS. 1-11). For a one-chip configuration and low power consumption, a MOS type Colpitts oscillator (FIG. 16) is provided with a circuit for adjusting the source resistance of the MOS. For size reduction and fine frequency adjustment, a DTCXO is provided with sections such as an adder 341, an up-down counter 342 and an auxiliary frequency control section (AFC) 332 (FIGS. 20, 21, 24 and 25). An adding section 415 is provided between a D/A converting section 414 and a capacitance varying section 416 to obtain superior linearity with respect to a control voltage and quality of offset.

Digital temperature compensated crystal oscillator

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Tokyo, Japan

Masaru Matsubayashi