Kddi Corporation

Keio University

Toshiaki Tanaka

Shinsaku Kiyomoto

Keisuke Takemori

Yutaka Miyake

Takamasa Isohara

Jun Kurihara

Iwao Sasase

A stream encryption device generates a first pseudo random number sequence from key information, generates a second pseudo random number sequence according to clock control performed according to the first pseudo random number sequence, and subjects it to a nonlinear function calculation, thereby generating a key stream. The stream encryption device performs XOR operation with a plain text so as to create an encrypted text.

Keystream encryption device, method, and program

A threshold secret sharing apparatus, a threshold secret sharing scheme, a secret information recovery apparatus a secret information recovery method, and a program thereof are provided using XOR computation, thereby offering a general (k,n) threshold secret sharing scheme with high computation speed. Secret information K is divided into (n&#x2212;1) divided pieces of secret information K(nis a prime number which is equal to or greater than a secret distribution number n). Furthermore, dummy secret information Kis generated. Moreover, random numbers R, which are mutually independent are generated. Then, pieces of shares are created using exclusive-OR (XOR) operations based upon the dummy secret information K, the divided piece of secret information K, and the random numbers R. The pieces of shares thus generated are concatenated so as to generate n shares S, thereby providing a (k,n) threshold secret sharing scheme.

Threshold secret sharing apparatus, threshold secret sharing scheme, secret information decryption method, and program for the same

A stream encryption device generates a first pseudo random number sequence from key information, generates a second pseudo random number sequence according to clock control performed according to the first pseudo random number sequence, and subjects it to a nonlinear function calculation, thereby generating a key stream. The stream encryption device performs XOR operation with a plain text so as to create an encrypted text. The stream encryption device performs an encryption process in units of words by using a clock controller. It includes: a first pseudo random number generation means to generate a first pseudo random number sequence from key information; a second pseudo random number generation means to generate a second pseudo random number sequence based on clock control performed according to the first pseudo random number sequence; and, a keystream generation means to generate a keystream by applying a nonlinear function calculation to the second pseudo random number sequence.

A communication system and a security assurance device are proposed, which are capable of assuring that a target party for communication is implementing security countermeasures. A servertransmits informationnecessary for AC issuance to a security assurance authority. The security assurance authorityverifies the security of the serverduring communication based upon this information necessary for AC issuance. And, when the security of the serverduring communication is confirmed, the security assurance authorityissues an ACwhich proves the security of the serverduring communication, and transmits it to the server. Upon receipt of this AC, the servertransmits the ACto a client, according to a connection request from the client. And, upon receipt of this AC, the clientverifies the security during communication of the server, based upon the AC

Growing community of inventors

Fujimino, Japan

Toshiaki Tanaka