Data protection method and storage device

The present invention discloses data protection method, applied to a storage device, and performed by a controller of the storage device. The data secure method comprises: receiving a buffer clear command from an external processing unit, wherein the buffer clear command indicates that a first secure area corresponding to a first physical address range of a buffer memory of the storage device is required to be cleared, and a first secure key is corresponding to the first secure area for accessing the first secure area; and in response to the buffer clear command, configuring a secure unit of the storage device to cause the secure unit to use one or more second keys different from the first secure key when accessing the first physical address range.