A homomorphic encryption operation key management system comprising: a communication interface configured to support communication using a security protocol; a memory; and at least one processor operatively coupled to the communication interface and the memory, wherein: the memory includes a token and one or more public keys received from each of a plurality of electronic devices; the at least one processor verifies validity of the token in response to the communication interface receiving a token and an operation key request from a first server; one or more homomorphic encryption operation keys are generated using the one or more public keys for a first electronic device among the plurality of electronic devices based on data obtained by decrypting the token in response to the token being valid; and the homomorphic encryption operation key for the first electronic device is transmitted to the first server through the communication interface, characterized in that: the one or more public keys include a hierarchical Galois key corresponding to a k-step shift; and the at least one processor generates one or more homomorphic rotation operation keys corresponding to the k-step shift by repeatedly performing a rotation operation using the hierarchical Galois key. a communication interface configured to support communication using a security protocol; a memory; and at least one processor operatively coupled to the communication interface and the memory, wherein: the memory includes a token and one or more public keys received from each of a plurality of electronic devices; the at least one processor verifies validity of the token in response to the communication interface receiving a token and an operation key request from a first server; one or more homomorphic encryption operation keys are generated using the one or more public keys for a first electronic device among the plurality of electronic devices based on data obtained by decrypting the token in response to the token being valid; and the homomorphic encryption operation key for the first electronic device is transmitted to the first server through the communication interface, characterized in that: the one or more public keys include a hierarchical Galois key corresponding to a k-step shift; and the at least one processor generates one or more homomorphic rotation operation keys corresponding to the k-step shift by repeatedly performing a rotation operation using the hierarchical Galois key. the memory includes a token and one or more public keys received from each of a plurality of electronic devices; the at least one processor verifies validity of the token in response to the communication interface receiving a token and an operation key request from a first server; one or more homomorphic encryption operation keys are generated using the one or more public keys for a first electronic device among the plurality of electronic devices based on data obtained by decrypting the token in response to the token being valid; and the homomorphic encryption operation key for the first electronic device is transmitted to the first server through the communication interface, characterized in that: the one or more public keys include a hierarchical Galois key corresponding to a k-step shift; and the at least one processor generates one or more homomorphic rotation operation keys corresponding to the k-step shift by repeatedly performing a rotation operation using the hierarchical Galois key. the one or more public keys include a hierarchical Galois key corresponding to a k-step shift; and the at least one processor generates one or more homomorphic rotation operation keys corresponding to the k-step shift by repeatedly performing a rotation operation using the hierarchical Galois key.