Key encryption methods, apparatuses and systems are disclosed in the embodiments of the present disclosure. A client does not store an encryption algorithm used for encrypting a key, but only stores an information header encrypted by the encryption algorithm, so that an attacker cannot directly obtain the encryption algorithm that is used for decrypting the information header even if the client is attacked, thus improving the security of the key in the client. When the key is needed to be used to encrypt obtained data, the client can use the stored first information header to request the key from the server, and the server having a higher security restores the key based on a stored first encryption algorithm. The client can encrypt the data using the key obtained from the server, so that the client can ensure the security of the obtained data without storing the encryption algorithm.