Crypto Lab Inc.

Microsoft Technology Licensing, LLC

Kyoohyung Han

Jung Hee Cheon

Yongsoo Song

Duhyeong Kim

Hao Chen

Andrey Kim

Miran Kim

Systems and methods for enabling constant plaintext space in bootstrapping in fully homomorphic encryption (FHE) are disclosed. A computer-implemented method for producing an encrypted representation of data includes accessing a set of encoded digits. The method includes applying an inverse linear transformation to the set of encoded digits to obtain a first encoded polynomial. The method includes applying a modulus switching and dot product with bootstrapping key to add an error term to each of the encoded digits in the first polynomial to obtain a second encoded polynomial. The method includes applying a linear transformation to the second encoded polynomial to obtain a first batch encryption. The method includes applying digit extraction to the first batch encryption to obtain a second batch encryption, the second batch encryption corresponding to the set of encoded digits without the error term.

Enabling constant plaintext space in bootstrapping in fully homomorphic encryption

An operation apparatus and method for processing a homomorphic encrypted message are disclosed. The method includes producing an approximate polynomial corresponding to an operation function to be applied to a homomorphic encrypted message and approximately operating the homomorphic encrypted message using the approximate polynomial. Thus, an encrypted message may be efficiently processed.

Apparatus for approximately processing encrypted messages and methods thereof

A decryption method includes: receiving a homomorphic ciphertext; and obtaining a result value added an error value at a message from the received homomorphic ciphertext. The error is disposed on the least significant bit (LSB) side in the homogeneous ciphertext, and the message is disposed at a position adjacent to the error.

Terminal device performing homomorphic encryption, server device processing ciphertext and methods thereof

An encryption method of a terminal device includes: setting a scaling factor; and reflecting the scaling factor in a message to be encrypted, and performing encryption using a public key to generate a homomorphic ciphertext. The homomorphic encryption is, based on a decryption being performed, in a form that a result value obtained by adding an error value to a value obtained by reflecting the scaling factor in the message is restored.

An encryption method is provided. According to the encryption method, a scaling factor may be reflected in a message and then, a homomorphic ciphertext may be generated using a public key. The generated ciphertext is, when decryption is performed, generated in a form that a result value obtained by adding an error value to a value obtained by reflecting the scaling factor in the message is restored. Accordingly, a homomorphic ciphertext capable of being computed in a ciphertext state can be effectively generated.

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Goyang-si, South Korea

Kyoohyung Han