Key conversion method, system and device for homomorphic cryptographic operation and readable storage medium

The invention relates to the technical field of homomorphic encryption, in particular to a key conversion method for homomorphic cryptographic operation, and the method comprises the following steps:processing ciphertext data input from the outside, converting the ciphertext data into extended key parameters, and caching the data input from the outside; performing polynomial operation on the extended key parameter and the cache data, and finally performing modular operation to obtain a dimension-reduced ciphertext. The invention further discloses a key conversion system for homomorphic cryptographic operation. The key conversion system comprises a conversion key generation module and a key conversion module. The invention also discloses computer equipment and a computer readable storage medium. When a computer program is executed by the processor, the steps of the key conversion method for homomorphic cryptographic operation are realized. The problems that an original fully homomorphic encryption scheme desig