1. A document processing method, comprising: dividing at least one document into a plurality of document pages through a client; individually encrypting the document pages by a first key to obtain a plurality of encrypted pages through the client; extracting a part of words from the document pages to obtain a plurality of significant words through the client; recording the significant words and page information of the significant word through the client; individually encrypting the significant words and the page information by a second key different to the first key to obtain an encrypted second document through the client; and transmitting the encrypted pages and the encrypted second document from the client to a remote server for storage.