Disclosed is an electronic apparatus. The electronic apparatus includes a memory storing a composite function in which at least two polynomials are composed and a processor configured to, based on a comparison operation command being received for a plurality of homomorphic ciphertexts, perform operation by reflecting the plurality of homomorphic ciphertexts to the composite function, and obtain a comparison result of the plurality of homomorphic ciphertexts based on the operation result, each of the at least two polynomials may output a value in a preset range for a value in a preset domain, and a domain of one of the at least two polynomials may be determined based on a range of a previous polynomial.