CN-116582238-B - Method for generating homomorphic rotation operation key, electronic device and server

CN116582238BCN 116582238 BCN116582238 BCN 116582238BCN-116582238-B

Abstract

The application discloses a method, an electronic device and a server for generating homomorphic rotation operation keys. In a client-server model for generating a rotation operation key in homomorphic encryption, a client transmits a public key generated using a secret key and a hierarchical galois key to a server, and the server performs rotation operation on the public key using the hierarchical galois key to directly generate one or more rotation operation keys, so that the server can generate rotation operation keys when necessary while reducing the computational burden and communication costs of the client.

Inventors

LU ZONGSHAN
LI JUNYU
JIN RONGZHI

Assignees

首尔大学校产学协力团
朝鲜大学敎产学协力团

Dates

Publication Date: 20260505
Application Date: 20230210
Priority Date: 20220210

Claims (15)

1. An electronic device, comprising: A communication interface configured to support communication using a security protocol; Memory including personal information data, and At least one processor operably coupled to the communication interface and the memory, wherein, The at least one processor: generating a ciphertext obtained by encrypting the personal information data according to homomorphic encryption, and generating a public key and one or more operation keys by using a secret key of the electronic device; transmitting the ciphertext, the public key, and the one or more operating keys to a server via the communication interface, and Receiving service information acquired based on homomorphic encryption operation on the ciphertext from the server, and The one or more operation keys correspond to some of all operation keys necessary for the homomorphic encryption operation, Wherein the one or more operation keys comprise a hierarchical Galois key for homomorphic encryption rotation operations, and the hierarchical Galois key generates a plurality of rotation operation keys for the homomorphic encryption rotation operations, The plurality of rotation operation keys are generated by repeatedly performing rotation operations on the public key using the hierarchical galois key.
2. The electronic device of claim 1, wherein the at least one processor generates the hierarchical galois key in response to a k-order shift and the plurality of rotational operation keys are generated in response to multiples of the k-order shift.
3. The electronic device of claim 2, wherein a master key corresponding to the k-order shift is generated in response to receiving a request from the server for the k-order shift for homomorphic encryption operations.
4. The electronic device of claim 1, wherein the one or more operation keys comprise a multiplication key, a conjugate complex key, and one or more hierarchical galois keys.
5. The electronic device of claim 4, wherein the at least one processor generates the one or more hierarchical galois keys in response to different step shifts.
6. The electronic device of claim 1, wherein the personal information data includes at least one of user sign data, photographs, moving images, and log data collected by the electronic device.
7. The electronic device of claim 1, wherein the server obtains the service information according to a result of performing a homomorphic encryption operation on the ciphertext to provide a neural network service, an artificial intelligence service, or a search service.
8. A server, comprising: A communication interface configured to support communication using a security protocol, and At least one processor operably coupled to the communication interface, wherein, The communication interface receives ciphertext, a public key, and a hierarchical galois key from an electronic device; the at least one processor generating a rotational operation key using the public key and the hierarchical Galois key in response to a data shift request for a homomorphic encryption operation of the ciphertext, and The at least one processor performs a rotation operation on the ciphertext using the rotation operation key, Wherein the at least one processor generates the rotation operation key by performing a rotation operation on the public key using the hierarchical galois key.
9. The server of claim 8, wherein the at least one processor uses the hierarchical galois key to generate a rotation operation key corresponding to a k-order shift.
10. The server of claim 9, wherein the at least one processor generates a plurality of rotation operation keys corresponding to multiples of the k-th order shift by repeatedly performing rotation operations on the public key using the hierarchical galois key.
11. The server of claim 8, wherein the at least one processor requests a hierarchical galois key from the electronic device for generating a rotation operation key corresponding to a k-order shift before receiving the hierarchical galois key.
12. The server of claim 8, wherein the at least one processor obtains service information from a result of performing homomorphic encryption operations on the ciphertext, and sends the service information to the electronic device to provide a neural network service, an artificial intelligence service, or a search service.
13. The server of claim 8, further comprising a memory, wherein, The rotation operation key is stored in the memory, and The at least one processor performs a rotation operation using the rotation operation key stored in the memory in response to a re-request for a k-order shift of the ciphertext.
14. The server of claim 13, wherein the at least one processor deletes the rotation operation key stored in the memory.
15. A method for generating homomorphic rotation operation keys for homomorphic ciphertext of an electronic device, the method comprising: Receiving ciphertext, a public key, and one or more operating keys from the electronic device; generating, by a processor, a rotating operation key using the public key and the one or more operation keys in response to a request for homomorphic rotating operation of the ciphertext, and Performing a rotation operation on the ciphertext using the rotation operation key by the processor, Wherein the rotation operation key is generated by performing a rotation operation on the public key by the processor using a hierarchical Galois key, A plurality of rotation operation keys are generated by repeatedly performing rotation operations on the public key by the processor using the hierarchical galois key.

Description

Method for generating homomorphic rotation operation key, electronic device and server Technical Field The present invention relates to homomorphic encryption technology, and more particularly, to a method of generating homomorphic rotation keys for performing rotation operations in homomorphic encryption. Background Homomorphic encryption (Homomorphic Encryption, HE) is an encryption method that can calculate data in an encrypted state. The result of the operation using the ciphertext becomes a new ciphertext, and the plaintext obtained by decrypting the ciphertext is identical to the result of the operation of the original data before encryption. Homomorphic encryption may be used to store personal information in an external medium or to calculate the personal information while securely protecting the personal information. For example, when homomorphic encryption is used, data may be outsourced to a business cloud service in an encrypted state and processed in an encrypted state. In homomorphic encryption, pieces of data are encrypted into one ciphertext, and when two different ciphertexts are operated on, the operation is performed between pieces of data at corresponding positions. When it is necessary to operate on data at different positions in ciphertext in an encrypted state, it is necessary to move the positions in some cases so that the operation can be performed. Only homomorphic rotation operation (which is a cyclic shift operation in an encrypted state) is an operation for changing a data position in a ciphertext in an encrypted state, and corresponds to a basic operation in using homomorphic encryption. Fig. 1 is a network environment of a conventional client-server model for performing homomorphic encryption operations. Referring to fig. 1, in a conventional client 1-server 2 model for performing homomorphic encryption operations, a client 1 generating ciphertext from homomorphic encryption may generate and transmit the necessary operation keys to request the server 2 to perform homomorphic encryption operations on the ciphertext. For example, the client 1 may generate a rotation operation key for performing a rotation operation according to homomorphic encryption using its secret key, and transmit the generated rotation operation key to the server 2, thereby performing the rotation operation on ciphertext in the server 2. The operation key required for homomorphic encryption may be generated from the secret key of the client 1 and thus cannot be generated in another electronic device (e.g., the server 2) that does not know the secret key. Disclosure of Invention In many cases, homomorphic rotation keys for performing rotation operations in homomorphic encryption occupy several hundred MB, and there are 100 or more types. Therefore, when all the rotation operation keys are generated in the client device and transmitted to the server, considerable costs are incurred. The present invention has been made in view of the above problems, and an object of the present invention is to provide a client-server model. Wherein the client authorizes the server to generate some operation keys for homomorphic encryption operations by newly proposing a method of generating operation keys for homomorphic encryption operations using a public key instead of a secret key of the client. It is another object of the present invention to provide a server configured to directly generate a necessary operation key using a public key of a client while performing a homomorphic encryption operation by granting generation rights of certain operation keys by the client, thereby performing the homomorphic encryption operation on ciphertext of the client. In accordance with one aspect of the present invention, the above and other objects can be accomplished by the provision of an electronic device comprising a communication interface configured to support communication using a secure protocol, a memory including personal information data, and at least one processor operatively coupled to the communication interface and the memory. Wherein the at least one processor generates a ciphertext obtained by encrypting the personal information data according to homomorphic encryption and generates a public key and one or more operation keys by using a secret key of the electronic device, transmits the ciphertext, the public key, and the one or more operation keys to a server through the communication interface, and receives service information acquired based on a homomorphic encryption operation on the ciphertext from the server, and the one or more operation keys correspond to some of all operation keys necessary for the homomorphic encryption operation. The one or more operation keys may include a hierarchical galois key for homomorphic encryption rotation operations, and the hierarchical galois key may generate a plurality of rotation operation keys for the homomorphic encryption rotation operations. The plurality of rotation operati