Samsung Sds Co., Ltd.

Korea Advanced Institute of Science and Technology

Duk Jae Moon

Hyo Jin Yoon

Eun Kyung Kim

Jin Hyuck Jeong

Young Hyun Kim

Joo Hee Lee

Jung Hoon Sohn

Seung Hyun Kang

Joo Young Lee

Ji Hoon Cho

Seong Kwang Kim

Ki Hyo Moon

Seung Ro Joo

Jin Cheol Ha

Kyu Young Choi

Ji Hoon Kwon

Won Seok Choi

Jang Hyuk Ahn

Min Cheol Son

Yong Ha Son

Byeong Hak Lee

A method for generating a key stream according to an embodiment includes generating r round keys that are each N-dimensional integer vectors including elements of an integer setdefined based on a prime number t, based on a random bit string, an encryption counter, and a secret key that is an N-dimensional integer vector consisting of elements of the integer set, generating a first round output vector xby performing a modular addition operation on an initial vector and a first round key RKof the r round keys with the prime number t as a modulus, and generating a key stream that is an N-dimensional integer vector consisting of elements of the integer setfrom the first round output vector xby using a second to r-th round keys of the r round keys, and one or more first round functions and a second round function.

Method and apparatus for generating key stream

A method for encryption according to an embodiment includes generating a ciphertext for a secret key that is an integer vector by using an integer-based first homomorphic encryption algorithm, generating a key stream that is the integer vector from a nonce and the secret key by using a key stream generator, encoding the key stream by using a message encoding function of the first homomorphic encryption algorithm, encoding a message that is a real vector by using a message encoding function of a real number-based second homomorphic encryption algorithm, generating a ciphertext for the message by using a result of the encoding of the key stream and a result of the encoding of the message, and transmitting the nonce, the ciphertext for the secret key, and the ciphertext for the message to an apparatus for converting a ciphertext.

Apparatus and method for encryption, apparatus and method for converting ciphertext

A method for data analysis according to an embodiment includes acquiring, from a client device, a ciphertext for a precomputation result generated by applying some of a plurality of operations for performing an analysis algorithm based on target data to the target data, and generating an encrypted computation result for remaining operations of the plurality of operations by using the ciphertext.

Apparatus and method for data analysis

A method for performing an operation according to an embodiment includes assigning an error value to encrypted data; and performing a homomorphic operation for an approximation function, which is obtained by approximating a target function, by using, as an input value, the encrypted data to which the error value is assigned.

Apparatus and method for performing operation using approximation function

An apparatus for set intersection operation according to an embodiment includes a ciphertext acquisition unit configured to acquire a ciphertext for a first vector corresponding to a first subset of a universal set including a plurality of elements from an encryption apparatus, a transform unit configured to generate a second vector corresponding to a second subset of the universal set, a computation unit configured to generate a ciphertext for a third vector corresponding to an intersection of the first subset and the second subset, based on the ciphertext for the first vector and the second vector, and a ciphertext providing unit configured to provides the ciphertext for the third vector to the encryption apparatus.

Apparatus and method for set intersection operation

A method for performing an operation according to one embodiment includes performing a homomorphic operation using one or more ciphertexts that are homomorphically encrypted based on an encryption key, determining a count value for a ciphertext generated through the homomorphic operation based on count values for each of the one or more ciphertexts, requesting a key management apparatus, which holds the encryption key and a decryption key corresponding to the encryption key, to re-encrypt the generated ciphertext based on the determined count value, acquiring, from the key management apparatus, a ciphertext generated by re-encrypting the generated ciphertext through decryption based on the decryption key and encryption based on the encryption key; and determining a count value for the acquired ciphertext to be a preset initial value.

Method and apparatus for performing operation using encrypted data

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Seoul, South Korea

Duk Jae Moon