In order to solve the problem that encryption files can not benefit from the data deduplication technology, a novel encryption scheme is proposed. According to the method, the basic encryption unit is transformed from the file to the chunks; and the chunk contents are used to generate the symmetric keys, which ensure the determinate mapping between plaintext and ciphertext of data. The data can be stored and transmitted in security as long as the adversary does not acquire a user's private key and identification password simultaneously. This scheme can mitigate the contradiction between traditional encryption method and deduplication technology well; and is suitable for the application of disk-based, data deduplication system which has the requirement of confidentiality.