公开(公告)号：US20250023717A1

公开(公告)日：2025-01-16

申请号：US18765390

申请日：2024-07-08

Applicant: NEC Corporation

Inventor： Hikaru TSUCHIDA ,  Takuya HAYASHI ,  Toshiyuki ISSHIKI ,  Kengo MORI ,  Yukimasa SUGIZAKI

IPC: H04L9/08 ,  H04L9/00

Abstract: A distributed re-encryption apparatus comprises: a distributed re-encryption key storage part that stores shares obtained by secret-sharing a re-encryption key that re-encrypts a ciphertext into one encrypted with a different encryption key without decrypting the ciphertext; and a distributed re-encryption part that re-encrypts using the shares of the re-encryption key the ciphertext into one encrypted with a different encryption key without decrypting the ciphertext.

公开(公告)号：US20230214666A1

公开(公告)日：2023-07-06

申请号：US18008492

申请日：2020-06-09

Applicant: NEC Corporation

Inventor： Hikaru TSUCHIDA

IPC: G06N3/098

CPC classification number: G06N3/098

Abstract: A client is provided with a property classification model training part that trains a classification model, the classification model inferring a property of an input data from the gradient information and a target model training part that computes the gradient information of the target model using a training data, the target model and the classification model and transmits the gradient information to the server. The property of the input data that the classification model infers can be set for each client, and the property classification model training part trains the classification model using the target model and a second training data labelled with a teacher label regarding the property of the input data.

公开(公告)号：US20220129567A1

公开(公告)日：2022-04-28

申请号：US17429780

申请日：2019-02-12

Applicant: NEC Corporation

Inventor： Hikaru TSUCHIDA ,  Toshinori ARAKI ,  Kazuma OHARA ,  Takuma AMADA

IPC: G06F21/60 ,  G06F21/31 ,  G06F7/58 ,  G06F7/76

Abstract: There is provided an information processing apparatus that executes efficient type conversion processing in four-party computation using 2-out-of-4 replicated secret sharing. The information processing apparatus comprises a basic operation seed storage part, a reshare value computation part, and a share construction part. The basic operation seed storage part stores a seed for generating a random number used when computation is performed on a share. The reshare value computation part generates a random number using the seed, computes a share reshare value using the generated random number, and transmits data regarding the generated random number to other apparatuses. The share construction part constructs a share for type conversion using the data regarding the generated random number and the share reshare value received from other apparatuses.

公开(公告)号：US20220035608A1

公开(公告)日：2022-02-03

申请号：US17276200

申请日：2018-09-20

Applicant: NEC Corporation

Inventor： Toshinori ARAKI ,  Hikaru TSUCHIDA ,  Kazuma OHARA

IPC: G06F8/41 ,  G06F8/51

Abstract: There is provided a conversion apparatus with which a secure computation execution environment may be easily constructed. The conversion apparatus comprises an input part and a conversion part. The input part inputs a source code. The conversion part converts the input source code so that a secure computation compiler processes it based on setting information relating to secret computation executed by a plurality of secure computation servers.

公开(公告)号：US20210351916A1

公开(公告)日：2021-11-11

申请号：US17283041

申请日：2018-10-11

Applicant: NEC Corporation

Inventor： Hikaru TSUCHIDA ,  Toshinori ARAKI ,  Kazuma OHARA

IPC: H04L9/08 ,  G06F7/72

Abstract: When an absolute value of a difference value between a first share and a second share which are secret-shared is less than or equal to a natural number t, the information processing apparatus calculates the difference value between the first share and the second share. Furthermore, the information processing apparatus performs a comparison in magnitude of the first share and the second share using bit-decomposition from a least significant bit to an m-th bit (m being a natural number) of the difference value.

公开(公告)号：US20200177389A1

公开(公告)日：2020-06-04

申请号：US16468336

申请日：2016-12-15

Applicant: NEC Corporation

Inventor： Hikaru TSUCHIDA ,  Kengo MORI ,  Toshiyuki ISSHIKI

IPC: H04L9/32 ,  H04L9/08 ,  H04L29/08

Abstract: In IaaS (Infrastructure as a Service), when it is desirable to delegate the authority to a user outside a system, a recipient of an access token is designated, thereby preventing illegal distribution of the access token. There is provided an access token system including a generator and a verifier. The generator generates, using secret information of a recipient, a recipient-designated access token for which the recipient is designated, and provides the recipient-designated access token to a user. The verifier verifies that the user who makes access using the recipient-designated access token is the designated recipient.

公开(公告)号：US20230333813A1

公开(公告)日：2023-10-19

申请号：US18023317

申请日：2020-08-26

Applicant: NEC Corporation

Inventor： Hikaru TSUCHIDA

IPC: G06F7/499 ,  G06F7/72

CPC classification number: G06F7/49931 ,  G06F7/723

Abstract: A secure computation system for secure exponentiation involving a non-secret base and a secret exponent comprises at least four secure computation server apparatuses connected to each other via a network, and each of the secure computation server apparatuses has: a reshare part that outputs reshares for an input including at least a share of the exponent by an operation closed within each of the secure computation server apparatuses; and a multiplication part that performs the secure exponentiation by executing multiplication using shares obtained by having the reshare part reshare the exponent that has been decomposed into additions of shares of the exponent.

公开(公告)号：US20230046000A1

公开(公告)日：2023-02-16

申请号：US17790572

申请日：2020-01-20

Applicant: NEC Corporation

Inventor： Hikaru TSUCHIDA

IPC: G06F21/71 ,  G06F21/55

Abstract: Each of a secure computation server apparatuses includes a random number generation part that generates random numbers using a pseudo random number generator shared among the secure computation server apparatuses; a seed storage part that shares and stores a seed(s) used for generating random numbers in the random number generation part; a pre-generated random number storage part that stores random numbers generated by the random number generation part; a share value storage part that stores a share(s) to be a target of processing; a logical operation part that computes a carry to be transmitted and received among the secure computation server apparatuses using the random numbers and the share(s) to be a target of processing; an inner product calculation part that removes a mask from the carry; and an arithmetic operation part that performs a processing of erasing the carry to obtain a processing result.

公开(公告)号：US20220399991A1

公开(公告)日：2022-12-15

申请号：US17779352

申请日：2019-11-28

Applicant: NEC Corporation

Inventor： Hikaru TSUCHIDA

IPC: H04L9/08

Abstract: The number of permutations is reduced when four-party shuffling is performed. Among four secure computation nodes holding first to third shares of data in a secret-shared form, first and second secure computation nodes are selected as resharing nodes, and third and fourth secure computation nodes are selected as receiving nodes. The first and second secure computation nodes perform a mini-shuffle for resharing the shares they each hold by using a permutation that third and fourth receiving nodes do not know. Next, the third and fourth secure computation nodes perform a mini-shuffle for resharing the shares they each hold by using a permutation that first and second receiving nodes do not know.

公开(公告)号：US20220343027A1

公开(公告)日：2022-10-27

申请号：US17762581

申请日：2019-09-26

Applicant: NEC Corporation ,  BAR-ILAN UNIVERSITY

Inventor： Toshinori ARAKI ,  Kazuma OHARA ,  Hikaru TSUCHIDA ,  Jun FURUKAWA ,  Binyamin PINKAS

IPC: G06F21/64

Abstract: A computation system according to the present disclosure includes: shuffling secure computation means for executing secure computation processing by shuffling; random bit sharing means for generating, as security parameters, K pieces of random data; and unauthorized action detecting secure computation means for determining that an exclusive OR operation of values for all rows obtained by multiplying the exclusive OR operation of each row of the tables before the shuffling processing for each data designated by the i-th random data by the i-th random bit of each row is the same as an exclusive OR operation of values for all rows obtained by multiplying the exclusive OR operation of each row of the tables after the shuffling processing for each data designated by the i-th random data by the i-th random bit of each row.