Patent ID: 8479300

Claim:
A method for transmitting data and preventing unauthorized data duplication for human-machine interface device (HID) using Mass Storage Class (MSC) operating on Universal Serial Bus (USB) simulating the HID as a USB storage device to transmit data to an external computer, the method comprising: a) receiving a password file, wherein the password file has a file name, and the password file records a dynamic password therein; b) determining a request of the external computer through the file name of the received password file by the HID as one of a file download request and a file upload request; c) transmitting a data file according to the request, wherein when the request is determined as a file download request in the step b, the HID receives a download data file encrypted by the dynamic password transmitted from the external computer, when the request is determined as a file upload request in the step b, step c further comprising: c1) writing an upload data file saved in the HID and encrypted by the dynamic password to the FAT by the HID thus the external computer is able to acknowledge existence of the upload data file; c2) permitting a data duplication of the upload data file by the HID when a replication request of the upload data file is correct following step c1; c3) when the data duplication of the upload data file executes once or the replication request of the upload data file is incorrect, deleting the upload data file from the FAT by the HID following step c2; d) decrypting the data file via the dynamic password recorded in the password file following step c; wherein the HID does not write the received password file to a File Allocation Table (FAT) thus the external computer is not able to acknowledge existence of the password file by accessing to the FAT.