Korea Advanced Institute of Science and Technology

Samsung Sds Co., Ltd.

Jin Cheol Ha

Hyo Jin Yoon

Joo Hee Lee

Joo Young Lee

Ji Hoon Cho

Duk Jae Moon

Seong Kwang Kim

Eun Kyung Kim

Won Seok Choi

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

Growing community of inventors

Daejeon, South Korea

Jin Cheol Ha