Abstract: A fully homomorphic encryption method based on modular operation, the method including: acquiring a plaintext of any numerical value data type in an encryption process and converting the plaintext to a corresponding plaintext system plaintext according to an encryption requirement; performing an encryption operation on each number in the system plaintext, and combining ciphertexts acquired by the encryption operation to obtain a corresponding ciphertext combination; performing a ciphertext operation on the ciphertext combination using a ciphertext source code, a ciphertext radix-minus-one complement, and a ciphertext complement code based on modular encryption; and using modular division to decrypt a result of the ciphertext operation to obtain a decrypted plaintext.

Abstract: A fully homomorphic encrypted ciphertext query method, the method including: acquiring a first plaintext, encrypting the first plaintext using a symmetric-key algorithm or a public-key algorithm to yield a first ciphertext, and storing the first ciphertext as a queried object; receiving a second plaintext which corresponds to a query condition, encrypting the second plaintext using a symmetric-key algorithm or a public-key algorithm to yield a second ciphertext, and storing the second ciphertext as a query object; performing bitwise summation on the queried object and the query object, to acquire a ciphertext query result; and decrypting the ciphertext query result to yield a decrypted plaintext, and comparing the decrypted plaintext with the second plaintext, determining, if the decrypted plaintext is the same as the second plaintext, the ciphertext query result is correct, and the query object exists in the queried object; otherwise, determining the ciphertext query result is incorrect.