# Kazuhiko Minematsu, Tokyo JP

## Kazuhiko Minematsu, Tokyo JP

Patent application number | Description | Published |
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20080253561 | Common-Key Block Encryption Device Common-Key Block Encryption Method, and Common-Key Block Encryption Program - 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. | 10-16-2008 |

20090138710 | Message Authentication Device, Message Authentication Method, Message Authentication Program and Storage Medium therefor - 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. The message authentication device includes: input means for inputting a message: padding means for padding the message, setting its length always to a constant of a block length, and outputting the message as a padded message; modified tree hash means for outputting hash values of one block by repeating a process of arranging hash functions with small input/output widths, corresponding to the padded message, generated based on parts of block cipher; adjustment value added encryption means for encrypting the hash values so as to set a tag; and output means for coupling and outputting the tag and the message. | 05-28-2009 |

20090196416 | TWEAKABLE BLOCK ENCRYPTION APPARATUS, METHOD, AND PROGRAM - 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. | 08-06-2009 |

20100329449 | ADJUSTMENT-VALUE-ATTACHED BLOCK CIPHER APPARATUS, CIPHER GENERATION METHOD AND RECORDING MEDIUM - 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. The adjustment-value-attached block cipher apparatus includes: an encryption section performing encryption by a block cipher system; an input section accepting plaintext, an adjustment value and instruction information indicating first or second cipher processing; and a generator dividing the adjustment value into first and second adjustment values, encrypting the first adjustment value using the encryption section to generate cipher for offset, determining an offset value according to the cipher for offset and the second adjustment value, determining the sum of the offset value and the plaintext, and encrypting the sum using the encryption section to generate first ciphertext when the instruction information indicates the first cipher processing, and encrypting the plaintext using the encryption section to generate second ciphertext when the instruction information indicates the second cipher processing. | 12-30-2010 |

20110150225 | ENCRYPTION DEVICES FOR BLOCK HAVING DOUBLE BLOCK LENGTH, DECRYPTION DEVICES, ENCRYPTION METHOD, DECRYPTION METHOD, AND PROGRAMS THEREOF - 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. | 06-23-2011 |

20110211691 | COMMON KEY BLOCK ENCRYPTION DEVICE, COMMON KEY BLOCK ENCRYPTION METHOD, AND PROGRAM - 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. | 09-01-2011 |

20120057702 | TAG GENERATION APPARATUS, TAG VERIFICATION APPARATUS, COMMUNICATION SYSTEM, TAG GENERATION METHOD, TAG VERIFICATION METHOD, AND RECORDING MEDIUM - 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. | 03-08-2012 |

20120269342 | BLOCK ENCRYPTION DEVICE AND METHOD AND COMPUTER PROGRAM - 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. | 10-25-2012 |

20120314857 | BLOCK ENCRYPTION DEVICE, BLOCK DECRYPTION DEVICE, BLOCK ENCRYPTION METHOD, BLOCK DECRYPTION METHOD AND PROGRAM - A block encryption device receives b-bit tweak T and generates, by keyed hash function employing key K | 12-13-2012 |

20130308775 | BLOCK ENCRYPTION DEVICE, DECRYPTION DEVICE, ENCRYPTING METHOD, DECRYPTING METHOD AND PROGRAM - A block encrypting device of the present invention includes: a mixing means ( | 11-21-2013 |