An electronic device comprising: a communication interface configured to support communication using a security 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 for 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 and based on the public key and the one or more operation keys from the server, the one or more operation keys correspond to some of all operation keys necessary for the homomorphic encryption operation, and wherein the one or more operation keys include a hierarchical Galois key for a homomorphic encryption rotation operation, wherein the hierarchical Galois key corresponds to a k-step shift operation in a homomorphic encryption operation and the hierarchical Galois key generates a rotation operation key for shifts of multiple of k for the homomorphic encryption rotation operation when rotation operation on the public key is repeatedly performed using the hierarchical Galois key, wherein the homomorphic encryption operation comprises the homomorphic encryption rotation operation. a communication interface configured to support communication using a security 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 for 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 and based on the public key and the one or more operation keys from the server, the one or more operation keys correspond to some of all operation keys necessary for the homomorphic encryption operation, and wherein the one or more operation keys include a hierarchical Galois key for a homomorphic encryption rotation operation, wherein the hierarchical Galois key corresponds to a k-step shift operation in a homomorphic encryption operation and the hierarchical Galois key generates a rotation operation key for shifts of multiple of k for the homomorphic encryption rotation operation when rotation operation on the public key is repeatedly performed using the hierarchical Galois key, wherein the homomorphic encryption operation comprises the homomorphic encryption rotation operation. 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 for 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 and based on the public key and the one or more operation keys from the server, the one or more operation keys correspond to some of all operation keys necessary for the homomorphic encryption operation, and wherein the one or more operation keys include a hierarchical Galois key for a homomorphic encryption rotation operation, wherein the hierarchical Galois key corresponds to a k-step shift operation in a homomorphic encryption operation and the hierarchical Galois key generates a rotation operation key for shifts of multiple of k for the homomorphic encryption rotation operation when rotation operation on the public key is repeatedly performed using the hierarchical Galois key, wherein the homomorphic encryption operation comprises the homomorphic encryption rotation operation.