Hitachi, Ltd.

Other

Fujitsu Corporation

Hitachi Computer Peripherals Co., Ltd.

Seiichi Domyo

Kazuo Takaragi

Hiroshi Yoshiura

Naoya Torii

Hiroyoshi Tsuchiya

Kazue Sako

Hiroshi Miyauchi

Yasutsugu Kuroda

Hiroyuki Ando

Seiko Kanno

Masashi Yamazaki

Ichirou Morita

Takaki Kuroda

Taketoshi Sakuraba

Hisashi Hashimoto

Yumiko Sugita

Atsushi Kobayashi

Hidehisa Arikawa

Yutaka Otsu

Yoshiaki Hattori

Naofumi Shouji

Takeshi Tanida

Tooru Kawai

Masahiro Mambo

Eiji Okamoto

Masaki Tsuruki

Hirohiko Nakano

Hiromasa Murakami

Ichir{overscore (o)}u M{overscore (o)}rita

Deduplicated backup data of a plurality of generations are aggregated and stored. A storage apparatus is connected via a network to a host system making a content write request and includes a storage unit providing one or more containers composed of a specified storage area, and a back up unit storing the content in the container in accordance with a backup request from the host system; and wherein the backup unit cuts out the content into one or more chunks, detects a duplicate chunk, which is a duplicate of a chunk stored in the container, from the cutout chunks, and additionally writes the chunk, other than the duplicate chunk, to the container where the duplicate chunk is stored.

Storage apparatus and additional data writing method

A method and a device for managing a computer network, especially a technique for ensuring the security of a network. A computer network system in which computers are connected to each other through transmission lines, each computer stores the data which constitutes a moving type software exclusively used for security and transmitted together with a message when the computer transmits the message to another computer of the system, and executes the moving type software by using the stored data upon receiving a message from another computer.

Method and a device for sterilizing downloaded files

Method and a device for managing a computer network

Method and device for managing computer network

A key recovery condition encryption apparatus includes a hashing unit, a first concatenating unit, and a condition information encryption unit. The hashing unit calculates a hash value on the basis of a hash function using a key recovery information text serving as information necessary for performing key recovery. The first concatenating unit concatenates the hash value from the hashing unit to the key recovery condition. The condition information encryption unit encrypts a concatenating result from the first concatenating unit by using a first encryption key. Also is disclosed a key recovery condition decryption apparatus for decrypting the encrypted data from the above encryption apparatus.

Key recovery condition encryption and decryption apparatuses

The present invention has an object to overcome problems of a key recovery system using a conventional KRF system and to achieve efficient operation of the overall key recovery system. A key recovery system of the present invention includes check units,for checking whether a user has a recovery authorization for a common key KS, on the basis of a recovery condition RC specified by a recovery condition index RCI which is added to an encrypted message (encrypted message obtained by encrypting the common key KS with a public key KRCpub) supplied from a terminal (,to,) of the user concerned, and a key recovery control unit,which is provided separately from the check units,and decrypts the encrypted message with a private key KRCpri paired with the public key KRCpub to recover the common key. The check unit,supplies the common key KS recovered in the key recovery control unit,to the user concerned only when the user has the recovery authorization.

Key recovery system and key recovery method

A key recovery information distribution device is provided between a recoverer device and a key recovery device, recovers a data key for the recoverer device, and reduces the load of the recoverer device. Data is encrypted using the data key and stored with key recovery information. The recoverer device which decrypts the encrypted data distributes the key recovery information to key recovery devices through the key recovery information distribution device to recover key information. A recoverer is authenticated directly between the key recovery device and the recoverer device, and then the key information is transmitted to the recoverer device, and the recoverer device recovers the data key.

Key recovery system

When a secret is encrypted and stored, it is necessary to provide a countermeasure for the situation where a key is lost (key recovery system). In the present invention, a key recovery system for an enveloped data format in which a common key is used to encrypt a plaintext (secret) and a user's public key is used to encrypt the common key and attached to an encrypted text is provided. In the present invention, only the common key is decrypted to recover the secret without reconstruction of split secret keys kept in a plurality of key storage apparatuses.

Encrypted data recovery method using split storage key and system thereof

In a data compression method using dictionaries, there are adopted a dynamic dictionary and a static dictionary to prevent the deterioration in the data compression ratio in the leading portion of the input data which cannot be efficiently compressed using the dynamic dictionary. Moreover, the configuration removes the disadvantage of the deterioration in the data compression ratio because character strings having a low appearance frequency occupy a large portion of the dictionary. Data to be compressed is inputted via an input unit to be decomposed into input bit strings 202. Using the input bit string as a retrieval key, a bit string retrieval is conducted through the static dictionary by a decision unit and a reference unit. According to a result from comparison between the input bit string and a bit string of the static dictionary and a result from the retrieval by a retrieving unit through the dynamic dictionary, whether or not the input bit string is to be registered to the dynamic dictionary is determined. For registration of the input bit string, an index is added thereto by a register unit before the registration. The input bit string or an index matching the string is outputted as compressed data.

Method of and apparatus for compressing and decompressing data and data

A distributed file system in which the cache hit ratio of a client is enhanced to speed up a file access for each of users logging into the client. A file server includes an access frequency database in which the names of users are listed in association with the names of files that are frequently accessed by the individual users. Each client includes a log-in user table for entering the name of a user who is logging in, and a cache priority control module. The cache priority control module sets priority levels for the copies of the files stored in a cache area, on the basis of the contents of the access frequency database and the log-in user table. The set priority levels function as criteria when any of the file copies is to be expelled from the cache area. Owing to this construction, the copies of the files of high usage frequencies are preferentially kept in the cache area of the client for each user logging into this client, whereby the cache hit ratio can be enhanced to speed up the file access.

Distributed file system permitting each user to enhance cache hit ratio

An object management system is equipped with a single real object management system for managing a real file object such as data and a program based on a real directory object in a hierarchical structure, and also at least a single virtual object management system for managing a virtual file object corresponding to said file object based upon a virtual directory object which is independent of the directory object in a hierarchical structure.

Virtual object management system for managing virtual objects which

Growing community of inventors

Fujisawa, Japan

Seiichi Domyo