A secure Universal Serial Bus (USB) storage device includes a memory controller capable of storing data in and retrieving data from a memory. The secure USB storage device also includes a USB secure microcontroller capable of authorizing access to the memory through the memory controller to thereby secure the memory. The USB secure microcontroller is also capable of protecting the data stored in the memory to thereby secure contents of the memory. The USB secure microcontroller could include an SPI interface and/or a GPIO interface emulating one or more of an SPI interface and an MMC interface to the memory controller. The memory controller could include an SPI interface and/or an MMC interface to the USB secure microcontroller. The secure USB storage device may be enumerated by a USB host controller under one or more device classes.