Kddi Corporation

Other

Teruaki Honma

Keisuke Takemori

Takamasa Isohara

Katsuyuki Yamazaki

Kei Katou

Kenichi Yoshida

Akihiro Nakashima

Yoshiyuki Shibata

Hiromitsu Fujikawa

A communication system is provided, including a plurality of terminal devices and a root certification authority. Each of the plurality of terminal devices includes a certification authority key generation unit, a certification authority public key certificate acquisition unit that acquires a certification authority public key certificate, a certification authority key storage unit, a transmission unit, and a verification unit that verifies the certification authority public key certificate with a root certification authority public key certificate, and verifies a user in a case where the verification succeeds. The root certification authority includes a root certification authority key storage unit, a communication unit, and a certification authority public key certificate generation unit that generates the certification authority public key certificate by encrypting the certification authority public key with the root certification authority secret key. The communication unit transmits the certification authority public key certificate to a terminal device.

Communication system, hardware security module, terminal device, communication method, and program

A communication device includes: a first subscriber identification unit that stores first subscriber identification unit identification information associated with user identification information; and a communication unit that communicates with another communication device, the other communication device including a second subscriber identification unit that stores second subscriber identification unit identification information associated with user identification information. The first subscriber identification unit includes: a key memory unit that records a pair of a public key certificate and a secret key, the pair being shared with the second subscriber identification unit; a public key certificate generation unit that generates, using the secret key recorded in the key memory unit, a 'first public key certificate comprising the first subscriber identification unit identification information or the user identification information associated with the first subscriber identification unit identification information'; and a secret key memory unit that records a secret key paired with the first public key certificate.

Communication device, communication method and computer program

The present invention is to provide a mass mail detection device that eliminates the need for preparation of rules or learning in advance and operates at a high speed. Electronic mail collecting means analyzes the electronic mail delivery protocol that flows on the network, and extracts an electronic mail main text from the electronic mail traffic that flows on the network. Next, characteristic quantity conversion means calculates a number of hash values from the electronic mail main text, as the characteristic quantity of the mail. Finally, mass mail detection means compares the newly received electronic mail with the stored past electronic mails, and determines the similarity in accordance with a specific standard. If determined as being similar, the new mail is determined as a candidate for a mass mail (similar mails), and a prescribed number or more of similar mails are determined as a mass mail.

Mass mail detection system and mail server

Growing community of inventors

Tokyo, Japan

Teruaki Honma