With the continuous development of computer networks, cloud storage is now the mainstream way for people to store information, but some important information leaks in the process of storage, and information security issues have become the most concerned issue at present. Homomorphic encryption not only has the property of data encryption of traditional encryption algorithm, but also has the result of ciphertext operation equivalent to the corresponding plaintext operation. This paper proposes an improved scheme based on DGHV, it (MDGHV) is mainly implemented from two points: changing the encryption formula c = pq + 2r + m to c = pqr + m, the domain of clear text m is expanded to a custom value, which can be used as a parameter; without acquiring sensitive information, data owners can directly calculate multiple ciphertexts and ensure high efficiency to meet the security requirements of cloud environment. An improved scheme based on DGHV, which expands the plaintext domain and enable search encryption operation to encrypt larger values, thus improving the efficiency. The security of this algorithm still depends on the similar CCD problem, which can solve some practical security problems in the cloud environment.
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