MED [Management Encryption Device] hard disk data security lock is a management hard disk encryption device developed to protect the security of hard disk data. MED has a personalized encryption system, which is customized by the user's password and generated personalized encryption key through multi-layer calculation. It also adopts full hard disk encryption to protect the contents of each sector. In the hard disk, each magnetic track content is encrypted ciphertext, to achieve watertight data security.