Abstract: A method of applying multiple pipes to assist digital copyright management in a USB storage device is disclosed. Firstly, a USB storage device is connected to a host for sending a descriptor to the host on demand. Next, the host selects mass storage interfaces in accordance with the descriptor. If the host requires accessing digital signature or private key, it uses random number as coding parameter to produce coded password, and selects a non-1st Bulk output pipe to send the coded password to the USB storage device. Then, the USB storage device selects a non-1st Bulk input pipe for sending an acknowledgement of the coded password back to the host. Finally, if the password is identified right by the host, it uses the random variable as coding parameter to encrypt data and then transmit it through the non-1st Bulk output and input pipes.