Murakami Yasumichi

Bio: Murakami Yasumichi is an academic researcher. The author has contributed to research in topics: Cipher & Public-key cryptography. The author has an hindex of 3, co-authored 21 publications receiving 41 citations.

Encryption communication method and encryption communication system

Abstract: PROBLEM TO BE SOLVED: To provide an encryption communication method and an encryption communication system that can conduct encryption communication between entities with high security. SOLUTION: An entity (a) encrypts a session key to convert a plain text into an encrypted text with a common key Kab and transmits its encrypted information to an entity (b) together with the encrypted text C. The entity (b) decodes the session key from the encrypted information with a common key Kba and uses the session key to decode the encrypted text C into the original plain text M. Or the entity (a) uses the common key Kab and common information shared in common with the entity (b) at encryption communication to obtain the session key, encrypts the plain text M into the encrypted text C by using the obtained session key and transmits the encrypted text C to the entity (b). The entity (b) utilizes the common key Kba and its common share information to obtain the session key and uses the obtained session key to decode the encrypted text C into the original plain text M.

Re-synchronization device for error correction coder decoder

Abstract: PURPOSE: To attain re-synchronization by detecting out of synchronism between a coder and a decoder in the error correction coder decoder. CONSTITUTION: Received series data are given to a bit shift means 1 and its output is given to an error correction coder decoder 2. The error correction coder decoder 2 outputs data of decoded series and provides an output of a syndrome to a bit '1' generating rate detection means 3. An output of the bit '1' generating rate detection means 3 is given to a control means 4. The bit shift means 1 provides an output of data of the received series without any modification or after shifting the data by a prescribed bit number depending on a control input signal from the control means 4. COPYRIGHT: (C)1996,JPO

Method, device and program for reproducing password

Abstract: PROBLEM TO BE SOLVED: To reproduce a password PW, without having to store the password PW and answers A1 to An to questions, in a password-reproducing device. SOLUTION: Questions Q1 to Qn and a check symbol R(X) are stored in a password reproducing device 2. The check symbol R(X) is set as a check symbol with respect to a sequence string (vector), composed of the password PW and the answers A1 to An to the questions Q1 to Qn. A person himself who has forgotten the password inputs the answers A1 to An to the questions Q1 to Qn from the password reproducing device 2, and the password-reproducing device 2 reproduces a lost partial PW in a code word because (A1,..., An and R(X)) are a portion of an error correctable code word.

Input device for coding key or decoding key and communication device

Abstract: PURPOSE: To provide an input device for a coding key or a decoding key which is simple in control and input for a general user. CONSTITUTION: The coding key is generated by reading an original of an image showing the coding key and performing image processing to it. A coding means 4 codes a plain text by the coding key and transmits it. The decoding key is generated by reading the original of the image showing the decoding key and performing the image processing to it. A decoding means 8 decodes the received coded sentence by the decoding key and returns it to the plain text. A mosaic pattern is drawn on the original of the image showing the coding key or the decoding key, and whether it is white or black is decided at every minimum unit of a matrix, and 1 when it is white, and 0 when it is black is written in a memory storing the coding key or the decoding key.

Authenticating method using secrecy dispersing method

Abstract: PROBLEM TO BE SOLVED: To enable authentication by an authentication system which uses a secrecy dispersing method without showing secrecy. SOLUTION: A secrecy generating person secretly gives a secret key to a main contractor and subordinate contractors selected by the main contractor. When it is certified that the secret key of the main contactor can be generated on the basis of a set of secret keys of some subordinate contractor, the set is authenticated. Since the authentication can be carried out without showing the secrecy of the main contactor, this system is reusable.

Biometric input with encryption

Abstract: A fingerprint sensing device and recognition system is disposed within a PCMCIA card. Decryption and Encryption of electronic files on a personal computer is performed with an encryption key provided by the PCMCIA card in response to biometric data. In this fashion access to biometric data of authorised users need not be transmitted to another system. Alternatively, the device also comprises the encryption and decryption functions preventing the key from being transmitted.

Digital copyright management system using electronic watermark

Abstract: A system for managing a digital content, particularly a digital content to which a copyright is claimed, and a system for supplying a public-key which is used in the management of the digital content are provided. The digital content management program is embedded to an operating system of a user apparatus as a micro kernel, a watch program or a watch command which is linked to the digital content management program is transmitted to the user apparatus by using a network or data broadcasting, and thereby, the illegitimate usage of the digital content is watched. A visible watermark is added to the digital content when illegitimately utilized, to restrain later usage. Even in regular usage, the route of copying or transferring the digital content can also be ascertained by adding an invisible watermark. Further, a public-key is put in a public-key distribution screen to be distributed by the network or broadcasting. Image data to which information on owner of the public-key or on the user is added as an invisible electronic watermark, is entered to the public-key distribution screen, so that the authenticity of the public-key and the user is checked by the electronic watermark.

Information processing apparatus and method, information management apparatus and method, and information providing medium

Abstract: An information processing apparatus managed by a management apparatus to decrypt encrypted information and use resultant decrypted information. An efficient scheme is implemented for registering users of the system.

Security key distribution using key rollover strategies for wireless networks

Abstract: Security key distribution techniques using key rollover strategies for wireless networks are described. A number of keys are generated, usually by an access point. The present invention allows a standard mode and a mixed mode. In standard mode, each device on the network supports automatic key updates. In mixed mode, one or more devices on the wireless network require fixed keys. In both modes, a predetermined number of keys are determined and communicated to client devices that are accessing the wireless network. The predetermined number is determined so that a client device can miss a certain number of authentication periods without losing communication with the wireless network. Preferably, transmit keys used by an access point are different than the transmit keys used by the client devices that support automatic key updates.

Secret key generating method, common key generating method, encryption method, cryptographic communication method and cryptographic communication system

Abstract: At the time when generating a secret key of each entity by using each divided identification information (ID division vector) obtained by dividing identification information (ID vector) of each entity into a plurality of blocks and by using a secret symmetric matrix of each key generating agency (center), a part of the components of the symmetric matrix is extracted in accordance with each divided identification information (ID division vector) so that the extracted components are synthesized with a random number particular to each entity so as to generate a secret key of each entity.