POLYNOMIAL FULLY HOMOMORPHIC ENCRYPTION METHOD AND SYSTEM BASED ON COEFFICIENT MAPPING TRANSFORM

摘要

A polynomial fully homomorphic encryption method and system based on coefficient mapping transform. The method comprises: firstly, expressing plaintext into a polynomial specifying a mapping function and consisting of one group of random values, two groups of random coefficient factors and one random constant, and taking an expression specifying a mapping function and one group of random coefficient factors as keys; taking the other group of random coefficient factors, one group of random independent variables of the mapping function and the random constant as ciphertext for homomorphic operation; and performing three different mappings on a key part of the function and then performing numerical fitting to respectively obtain operation supporting function families formed by three subfunctions, wherein the operation supporting function families are used for remote ciphertext homomorphic operation based on the operation supporting function families and then returning to local for decrypting through the key. The present invention ensures that real values of data are only visible for a data owner having a key, and are represented in a ciphertext form for a data storage party, a data transmission pipeline and a data operation party which cannot guarantee the security of data, thereby providing a safe data storage and operation environment.