Highly secure portable storage device may include a security controller, a data transfer controller and a memory controller. The security controller self-verifies, without a host, an access code. After the verification, the security controller may retrieve a concealed encryption key and a transformation key that were previously self-generated by the security controller. The encryption keys are not generated by the host, a user, or the memory controller. The transformation key is sent to the memory controller via a side channel during a first time period. The concealed encryption key is sent to the memory controller via the side channel during a different time period. After extracting an operating encryption key, the memory controller may notify the data transfer controller to initiate an enumeration process with the host. Data transfer from and to the host is performed via interfaces different from the side channel. Other methods and implementations are also described.