US Patent 10025811 Method and apparatus for deduplicating encrypted data

In a client, an encryption key is created using plain text data, a first tag is created using the encryption key, and the plain text data are encrypted under the encryption key to create encrypted data. The first tag is transmitted to the server to confirm whether the encrypted data is duplicated and after transmitting the first tag, the encrypted data is transmitted to the server in accordance with the request of the encrypted data from the server.