Large file selective encryption method for reducing write

TL;DR: In this article, the authors proposed a large file encryption method, which adopts the following steps: storing an original plaintext, covering part of the plaintext that is encrypted, and separately storing an encrypted ciphertext.

Abstract: The invention belongs to the field of information security, relating to a large file encryption method. The method considers the phenomenon that a large file has huge data and is not suitable for full encryption, a large number of data will choose not to be encrypted, and in order to reduce the read and write of the data, especially the write, the method disclosed by the invention adopts the following steps: storing an original plaintext, covering part of the plaintext that is encrypted, and separately storing an encrypted ciphertext. As different encryption methods have different advantages and disadvantages, fully homomorphic encryption also cannot solve all delegated calculations, and a high cost of encryption is needed, an encryption mode with a misleading function is required for some data, and only a general symmetric encryption mode is required for other data, thereby, the appropriate encryption methods are segmentally selected as required, only part of the data needs to be encrypted according to rules or selections; and meanwhile, an optimum scheme for reducing key management and guaranteeing security is proposed, and thus the encryption and decryption of the files can be achieved by only using fewer keys.