A data security protection method generates dynamic encryption keys and dynamic decryption keys for a host and a client during data transmission between the host and the client. The host stores a host initial key K0, and determines a host key Kn using a one-way hash function based on the host initial key K0. The client stores a client initial key K′0, and determines a client key K′n using the one-way hash function based on the client initial key K′0. Original data Rn is encrypted as encrypted data Xn using the host key Kn before being sent to the client. The client decrypts the encrypted data Xn using the client key K′n, to obtain the original data Rn.