Fujitsu Corporation

Kouichi Itoh

Masahiko Takenaka

Dai Yamamoto

Jun Yajima

Naoya Torii

Tetsuya Izu

Kazuyoshi Furukawa

Souichi Okada

Hiroshi Tsuda

Masanobu Morinaga

Satoru Torii

Ikuya Morikawa

Takao Ochiai

Fumihiko Kozakura

Takeaki Terada

Kenji Mukaida

A determination apparatus has a feature extraction unit and a similarity determination unit. The feature extraction unit counts a number of appearances of each keyword included in a piece of document information and deletes any arrangement including a keyword having the number of appearances less than a threshold under a condition where a number of types of keyword arrangements included in a certain range of the piece of document information is equal to or greater than a certain number and extracts, as features, a plurality of keyword arrangements from the piece of document information. The similarity determination unit determines a similarity between the different pieces of document information by comparing the features extracted from pieces of document information different from each other.

Similarity determination apparatus, similarity determination method, and computer-readable recording medium

A computer is disclosed that performs an electronic mail creation process. The computer creates an electronic mail by referring to a storage part in which received electronic mails are stored, using at least one electronic mail of the received electronic mails stored in the storage part, the at least one electronic mail selected based on a criteria being set beforehand, and changing at least one of header information and a body text of the at least one electronic mail.

Electronic mail creation recording medium, method, and information processing apparatus

From the least significant bit of the current secret key, k bits are retrieved, obtaining a binary window sequence. A binary bit string of concatenation of the random number to the more significant bits of the window sequence is obtained if the most significant bit of the window sequence is 0, subtracting a bit string from the current secret key to obtain a new secret key, or the bit string of a complement of the base number for the window sequence in binary system is calculated if the most significant bit of the window sequence is 1, obtaining a bit string by adding a minus sign to a bit string obtained by concatenating the random number to the more significant bits of the bit string, subtracting the bit string from the current secret key to obtain a new secret key.

Encrypting device, encrypting method, and recording medium

k bits from the least significant bit of the current secret key are retrieved, obtaining a binary window sequence. A binary bit string of concatenation of the random number to the more significant bits of the window sequence is obtained if the most significant bit of the window sequence is 0, subtracting a bit string from the current secret key to obtain a new secret key, or the bit string of a complement of the base number for the window sequence in binary system is calculated if the most significant bit of the window sequence is 1, obtaining a bit string by adding a minus sign to a bit string obtained by concatenating the random number to the more significant bits of the bit string, subtracting the bit string from the current secret key to obtain a new secret key.

An encryption processing device includes a memory configured to store a common key, and a processor configured to generate a random number which is an integer, to perform a bit transposition on the common key, the bit transposition being determined at least by the random number, to transmit the random number to another encryption processing device and to receive a response from the other encryption processing device, the response obtained by encryption using a common key stored in the other encryption processing device and a second randomized key generated by performing the bit transposition determined by the random number; and to authenticate the other encryption processing device either by comparing the response with the random number by decrypting the response with the common key, or by comparing the random number with the response by encrypting the random number with the common key.

Encryption processing device and authentication method

A method is disclosed for authenticating, by a processor that controls a parent device, a child device includes: authenticating the child device by making a comparison between a value obtained by operating, for a first response value, a third transform function, which is decided based on a number of a difference between the value set in an authentication chip of the parent device and the value set in an authentication chip of the child device, and the second response value, wherein a first and a second response values are obtained by operating a first and a second transform functions for output values generated by operating an encryption function for performing encryption for secret keys in authentication chips of the parent device and the child device, respectively.

Authentication method, authentication system, and authentication chip using common key cryptography

A constant multiplier inputs a base and a modulo n, performs modular exponentiation modulo n with a prescribed constant as the exponent and with base a, and outputs the result of this calculation as base b. A personal key converter inputs a personal key d and calculates a personal key d' as the quotient when d is divided by the prescribed constant. A correction key generator generates a correction key d&#x2033; as the remainder of the aforementioned division. A first modular exponentiation unit performs modular exponentiation base b with d&#x2032; as the exponent. A second modular exponentiation unit performs modular exponentiation base a with d&#x2033; as the exponent, and outputs a correction value. A correction calculation unit multiplies the outputs of the first and second modular exponentiation units and outputs the result as the encryption processing result.

Encryption processing device and method

The generation of individual-specific information having a good reliability and uniqueness is made possible with a little circuit scale. For this purpose, in an individual-specific information generation apparatus, a plurality of digital circuits are in the same circuit configuration. Each of the digital circuits outputs a fixed or a random number output value individually without their output with respect to a certain input being determined unambiguously among the digital circuits. In each of the digital circuit, an order is defined in advance. A random number judgment unit judges whether the output value is a random value or fixed, for each of the plurality of digital circuits. An individual-specific information generation unit generates the individual-specific information based on information of the order defined in the digital circuit judged by the random number judgment unit as having a fixed output value among the plurality of digital circuits and the output value.

Individual-specific information generation apparatus and individual-specific information generation method

A random number generator includes an exclusive-OR circuit, a random number determiner, and a random number generation instruction inhibitor. The exclusive-OR circuit obtains an exclusive-OR of outputs from a number of digital circuits. The random number determiner determines whether or not an output generated according to an instruction to generate random numbers is a random number for each of the digital circuits. The random number generation instruction inhibitor inhibits an instruction to generate random numbers to be provided to the digital circuits whose output generated according to the instruction is determined to be not a random number by the random number determiner.

Random number generator, encryption device, and authentication device

A cryptographic processing device includes a private key storage unit which stores a private key d for elliptic curve cryptography, a random number generation unit which generates a b-bit random value s, and a processing unit. A bit string D is the private key d or a bit string obtained by modifying the private key d in such a way that a value of a most significant bit is 0, and a relation u=mk+b holds true for a length u of the bit string D, a window size k, and a positive integer m. The processing unit determines a signed k-bit window value w[i] corresponding to each i where 0&#x2266;i&#x2266;(m&#x2212;1), a signed b-bit random value s[i] corresponding to each i, and a correction value g. The processing unit determines the above values under a certain constraint condition, while determining each random value s[i] to be +s or &#x2212;s.

Cryptographic processing device and cryptographic processing method

Based on an encrypting method for performing an exponential remainder calculation y=a(mod n) from an u-bit exponent d=(d, . . . , d), input data a, and a modulo n, calculating a'=a(mod n) is performed first. Next, calculating y=(a&#x2032;)(mod n) is performed on f=(d, d, . . . , d). Then, when d=1, calculating y=y&#xd7;a (mod n) is performed. Then, outputting y=a(mod n) is performed. In the first step, although an attacker inputs data including a minus value such as a=&#x2212;1 and a=s, &#x2212;s, etc., only plus values can be constantly generated in multiplication and squaring. Therefore, the method makes it hard to estimate a secret key using power analyzing attacks such as the SPA and the DPA, thereby realizing an encryption processor having high tamper-resistance.

Encrypting method having countermeasure function against power analyzing attacks

stores, in, key d' obtained by subtracting random number 2r held infrom key d held in. When an operation starts, the values '&#x2212;C' and '&#x2212;C' are calculated respectively, and the resultant values are stored in a multiplication table memorytogether with value &#x201c;C&#x201d;. In a first operation cycle,selects and outputs an intermediate valueheld in an in-operation data register, and thereby makes a modular-multiplication operation circuitperform squaring. In the second operation cycle,selects and outputs one of three values held inin accordance with the combination of key bit value d&#x2032;and random number bit value r, and thereby makes the modular-multiplication operation circuitperform multiplication. Thereby, a cryptographic processing device that requires a short operation time period, small circuit scale, and has sufficient security can be realized.

Cryptographic processing method, computer readable storage medium, and cryptographic processing device

A cipher processing apparatus for arithmetic operations of an FO function and an FL function comprising: an FL function operating unit for generating a 2N-bit output based on a first extension key; a partial function operating unit for generating an N-bit output based on second and third extension keys; an N-bit intermediate register for storing an output of the partial operating unit; a 2N-bit first data register for storing data based on the output of the FL function operating unit; and a controller for making the partial function operating unit perform six cycles, inputting an output of the intermediate register to the FL function operating unit, and storing the data based on the output of the FL function operating unit in the first data register, in a first case in which the FL function uses a result of an arithmetic operation of the FO function.

Cipher processing apparatus

An apparatus includes a data storage to store a window table storing a table value with an index value mapped to the table value, the index value having same number of bits as a window width, the table value being a sum of a basic table value and a non-zero table correction value, the basic table value being obtained by multiplying a point G on an elliptic curve. An arithmetic processor generates the index value by reading from a scalar value at a bit position assigned to each bit of the window with the window being shifted, reads the table value from the window table according to the index value, and performs a doubling operation and an addition operation using the read table value. A corrector performs a correction on arithmetic results with a specific correction value responsive to the table correction value.

Method and apparatus for elliptic curve cryptographic processing

A randomly selected point on an elliptic curve is set as the initial value of a variable and calculation including a random point value is performed in an algorithm for calculating arbitrary scalar multiple operation on an elliptic curve when scalar multiplication and addition on an elliptic curve are defined, then a calculation value obtained as a result of including a random point is subtracted from the calculation result, whereby an intended scalar multiple operation value on an elliptic curve is determined.

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Kawasaki, Japan

Kouichi Itoh