Document similarity calculation method facing cloud storage based on fully homomorphic password technology

The invention discloses a document similarity calculation method facing cloud storage based on a fully homomorphic password technology. The method comprises the following steps that a data owner uploads a document ID, an encrypted document cryptograph and a cryptograph of a document Hash value to a cloud server; a public key certificate is issued to a cloud service provider and a data user; the data user encrypts a simhash value of a document with a similarity to be calculated and uploads to the cloud service provider; the cloud service provider carries out fully homomorphic addition operation of a document simhash cryptograph value to be calculated and a data owner document simhash cryptograph value and returns an operation result to the data owner; the data owner acquires Hamming distances between the documents and returns a document ID with a top distance sorting to the cloud service provider. By using the method, the calculation is performed under a cryptograph state. During a calculation process, any information related to the document is not revealed to the cloud service provider and other attackers so that a data secret of the data owner and a query data secret of the data user are protected.