Patents by Inventor Kazuhiko Minematsu

Kazuhiko Minematsu has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20140137211
    Abstract: The present invention has: a dynamic random access memory (DRAM); a refresh controller that receives information related to a range of the number of lost bits that are lost by stopping refresh processing of the DRAM, and controls a time to stop the refresh processing to achieve the range of the number of lost bits; and a physical information mapping unit that generates device specific information based on position information of the lost bits generated by stopping the refresh processing. It is preferable that the refresh controller corrects the time to stop the refresh processing based on the number of current lost bits to achieve the range of the number of lost bits set.
    Type: Application
    Filed: June 27, 2012
    Publication date: May 15, 2014
    Applicant: NEC CORPORATION
    Inventors: Kazuhiko Minematsu, Toshihiko Okamura, Yukiyasu Tsunoo
  • Publication number: 20130308775
    Abstract: A block encrypting device of the present invention includes: a mixing means (101) that applies universal hash function-based permutation to the (n+m)-bit plaintext to generate a first intermediate variable of n bits and a second intermediate variable of m bits; a first tweakable unit block encrypting means (102) that encrypts the first intermediate variable by use of an encrypting function of an m-bit tweakable n-bit block cipher, using the second intermediate variable as the tweak to generate a third intermediate variable of m bits and a fourth intermediate variable of (n?m) bits; a second tweakable unit block encrypting means (103) that encrypts an n-bit intermediate variable formed by connecting the second intermediate variable and the fourth intermediate variable, by use of the encrypting function, using the third intermediate variable as the tweak to generate a fifth intermediate variable of n bits; and an inverse mixing means (104) that applies universal hash function-based inverse-permutation to result
    Type: Application
    Filed: January 23, 2012
    Publication date: November 21, 2013
    Applicant: NEC CORPORATION
    Inventor: Kazuhiko Minematsu
  • Patent number: 8589688
    Abstract: A message authentication device, a message authentication method, a message authentication program and a storage medium therefor are provided, so as to realize higher speed processing than an authentication mode of existing block cipher, in combination of block cipher and one of its parts, with theoretical security in accordance with a high efficient preliminary process and with an efficient amount of available memory.
    Type: Grant
    Filed: October 19, 2006
    Date of Patent: November 19, 2013
    Assignee: NEC Corporation
    Inventor: Kazuhiko Minematsu
  • Patent number: 8577032
    Abstract: A common key block encryption device includes a first hash unit applying locked key permutation to a variable-length s-bit plaintext, and outputting a fixed-length n-bit first block and a second (s-n)-bit block; a first encryption processing unit outputting a third block encrypted by element of n-bit block tweakable block cipher using tweak, inputting the first block; a second encryption processing unit generating a random number (s-n)-bit block with a result of group computation of the third block and the first block as input by using an arbitrary cipher having theoretical security at least against a known-plaintext attack; and a second hash unit applying the locked key permutation to the result of the group computation of the random number block and the second block, and to the third block to output a fifth n-bit block and a sixth (s-n)-bit block. The fifth and sixth blocks are concatenated into an s-bit encryption.
    Type: Grant
    Filed: August 1, 2008
    Date of Patent: November 5, 2013
    Assignee: NEC Corporation
    Inventor: Kazuhiko Minematsu
  • Patent number: 8543820
    Abstract: The tag generation apparatus of the present invention includes a hash unit (12) that applies a hash function to a message to generate a hash value, a random number encryption unit (14) that applies an encryption function having a first key to a random number that is independent of the message to generate a first intermediate variable, a masked encryption unit (15) that applies the encryption function having a second key to the sum of the random number and the hash value to generate a second intermediate variable, and a tag generation unit (16) that generates as the tag a value contained in bits of a predetermined number of bits that is less than or equal to the number of bits of the random number and that are extracted from the exclusive OR of the first intermediate variable and the second intermediate variable.
    Type: Grant
    Filed: April 26, 2010
    Date of Patent: September 24, 2013
    Assignee: NEC Corporation
    Inventor: Kazuhiko Minematsu
  • Patent number: 8526602
    Abstract: There is provided an adjustment-value-attached block cipher apparatus realizing block cipher processing that the amount of processing is small in adjustment-value-attached block cipher.
    Type: Grant
    Filed: April 8, 2009
    Date of Patent: September 3, 2013
    Assignee: NEC Corporation
    Inventor: Kazuhiko Minematsu
  • Publication number: 20120314857
    Abstract: A block encryption device receives b-bit tweak T and generates, by keyed hash function employing key K2, mask value S of n bits and intermediate value V of m bits, m being positive integer less than n/2; with block cipher being of block size of n bits, with key length being n bits and with tweak being of length of b bits; enhances intermediate value V to n bits on padding, and encrypts enhanced intermediate value V with block cipher of n bits, using key K1, to generate tweak dependent key L of n bits; and adds mask value S to plaintext of n bits to generate first value, encrypts first value with n-bit block cipher having tweak dependent key L as key to generate second value, and adds the mask value S to second value to generate ciphertext.
    Type: Application
    Filed: February 22, 2011
    Publication date: December 13, 2012
    Inventor: Kazuhiko Minematsu
  • Publication number: 20120269342
    Abstract: In block cipher based on generalized Feistel network, pseudorandomness and strong-pseudorandomness may be fulfilled efficiently. In encrypting a plaintext of kn-bit blocks, Feistel permutation is applied in terms of 2n bits as a unit, and then block-based permutation based on a binary de Bruijn graph with symmetrical type 2 branch coloring is applied. The Feistel permutation and the block-based permutation are grouped together to form a round. The round is repeatedly performed a preset number of times to output a ciphertext.
    Type: Application
    Filed: October 26, 2010
    Publication date: October 25, 2012
    Applicant: NEC CORPORATION
    Inventor: Kazuhiko Minematsu
  • Patent number: 8189770
    Abstract: The tweakable block cipher system and method also includes an offset calculation unit that calculates a sum of a value, which is generated by encrypting a constant plaintext using a block cipher, and the tweak and outputs a value which is generated by encrypting the result using a partial block cipher as an offset. Furthermore, an internal encryption unit calculates a sum of the offset and the plaintext, encrypts the sum using the block cipher, calculates a sum of the result and the offset, and outputs the sum as a ciphertext. In addition, the system and method includes an output unit that outputs the ciphertext.
    Type: Grant
    Filed: July 27, 2007
    Date of Patent: May 29, 2012
    Assignee: NEC Corporation
    Inventor: Kazuhiko Minematsu
  • Publication number: 20120057702
    Abstract: The tag generation apparatus of the present invention includes a hash unit (12) that applies a hash function to a message to generate a hash value, a random number encryption unit (14) that applies an encryption function having a first key to a random number that is independent of the message to generate a first intermediate variable, a masked encryption unit (15) that applies the encryption function having a second key to the sum of the random number and the hash value to generate a second intermediate variable, and a tag generation unit (16) that generates as the tag a value contained in bits of a predetermined number of bits that is less than or equal to the number of bits of the random number and that are extracted from the exclusive OR of the first intermediate variable and the second intermediate variable.
    Type: Application
    Filed: April 26, 2010
    Publication date: March 8, 2012
    Inventor: Kazuhiko Minematsu
  • Publication number: 20110211691
    Abstract: A common key block encryption device includes a first hash unit applying locked key permutation to a variable-length s-bit plaintext, and outputting a fixed-length n-bit first block and a second (s-n)-bit block; a first encryption processing unit outputting a third block encrypted by element of n-bit block tweakable block cipher using tweak, inputting the first block; a second encryption processing unit generating a random number (s-n)-bit block with a result of group computation of the third block and the first block as input by using an arbitrary cipher having theoretical security at least against a known-plaintext attack; and a second hash unit applying the locked key permutation to the result of the group computation of the random number block and the second block, and to the third block to output a fifth n-bit block and a sixth (s-n)-bit block. The fifth and sixth blocks are concatenated into an s-bit encryption.
    Type: Application
    Filed: August 1, 2008
    Publication date: September 1, 2011
    Applicant: NEC CORPORATION
    Inventor: Kazuhiko Minematsu
  • Publication number: 20110150225
    Abstract: An encryption device for a block having double block length permutates a plaintext of 2 n bits based on a universal hash function so as to generate first and second intermediate variables of n bits each, encrypts the first intermediate variable with a tweak that is a result in which the second intermediate variable is shortened to m bits using an encryption function for m-bit tweak n-bit block cipher so as to generate a third intermediate variable of n bits, encrypts the second intermediate variable with a tweak that is a result in which the third intermediate variable is shortened to m bits using the encryption function so as to generate a fourth intermediate variable of n bits, concatenates the third and fourth intermediate variables and inversely mingles the concatenated result based on a universal hash function so as to generate a ciphertext of 2 n bits.
    Type: Application
    Filed: May 22, 2009
    Publication date: June 23, 2011
    Inventor: Kazuhiko Minematsu
  • Publication number: 20100329449
    Abstract: There is provided an adjustment-value-attached block cipher apparatus realizing block cipher processing that the amount of processing is small in adjustment-value-attached block cipher.
    Type: Application
    Filed: April 8, 2009
    Publication date: December 30, 2010
    Applicant: NEC Corporation
    Inventor: Kazuhiko Minematsu
  • Publication number: 20090196416
    Abstract: A tweakable block cipher apparatus includes an input unit that receives a pair of a plaintext M and a tweak; an offset calculation unit that calculates a sum of a value (E(K, const)), which is generated by encrypting a constant plaintext (constant const) using a block cipher, and the tweak and outputs a value (G(Ksub, E(K, const)+tweak), which is generated by encrypting the result (E(K, const)+tweak) using a partial block cipher (G), as an offset; an internal encryption unit that calculates a sum of the offset and the plaintext M, encrypts the sum using the block cipher E, calculates a sum (E(K, M+offset)+offset) of the result (E(K, M+offset)) and the offset, and outputs the sum as a ciphertext (C); and an output unit that outputs the ciphertext.
    Type: Application
    Filed: July 27, 2007
    Publication date: August 6, 2009
    Inventor: Kazuhiko Minematsu
  • Publication number: 20090138710
    Abstract: A message authentication device, a message authentication method, a message authentication program and a storage medium therefor are provided, so as to realize higher speed processing than an authentication mode of existing block cipher, in combination of block cipher and one of its parts, with theoretical security in accordance with a high efficient preliminary process and with an efficient amount of available memory.
    Type: Application
    Filed: October 19, 2006
    Publication date: May 28, 2009
    Inventor: Kazuhiko Minematsu
  • Publication number: 20080253561
    Abstract: Disclosed is a common-key block encryption device including first Feistel-type hash means that divides a plain text into a PA block and a PB block and adds the PB block, which is compressed by a hash function, and the PA block to generate a unit block intermediate text; unit block encryption means that encrypts the unit block intermediate text to generate a unit block intermediate cipher text; pseudorandom number generation means that generates an intermediate random number based on the unit block intermediate cipher text; addition means that adds the intermediate random number and the PB block and outputs an addition result; second Feistel-type hash means that outputs a result that is a combination of a second addition result, generated based on the addition result compressed by a hash function and the unit block intermediate cipher text, and the addition result; and cipher text output means that outputs the output result as a cipher text.
    Type: Application
    Filed: December 12, 2005
    Publication date: October 16, 2008
    Applicant: NEC CORPORATION
    Inventor: Kazuhiko Minematsu
  • Patent number: 6700993
    Abstract: To improve a reliability of watermark detection, by making it difficult for a user to falsify watermarked image. User terminal extracts the embedded watermark by using an extraction key generated by a detection center, and encrypts it by an encryption key generated by the detection center. The user terminal also encrypts by using the encryption key authentication information which is prescribed. Then, the user terminal outputs toward the detection center a first information which is a random combination of the encrypted watermark and the encrypted authentication information. The first information is decoded and quantized by the detection center. Then, the detection center transmits a second information namely the quantized first information toward the user terminal. Finally, the user terminal authenticates the watermark on the basis of the second information.
    Type: Grant
    Filed: September 6, 2000
    Date of Patent: March 2, 2004
    Assignee: NEC Corporation
    Inventor: Kazuhiko Minematsu
  • Publication number: 20020154772
    Abstract: It is characterized to comprise an authentication device 4 having invalid information of a key in relation to cryptology, and for disapproving authentication in case that information of an authentication key is included in the invalid information, which is used for authentication when a first cryptographic key in relation to encrypting is shared between a first encrypting device 3 and a first decryption section 11, and an certificate revocation list updating device 5 for updating contents of the invalid information in the authentication device 4 when receiving information of a key of an object to be invalidated, which is provided together with an input data in relation to a work.
    Type: Application
    Filed: April 17, 2002
    Publication date: October 24, 2002
    Inventors: Takuya Morishita, Hiroshi Miyauchi, Kazuhiko Minematsu, Satoshi Obana