I have an application where secret data is transferred in/out of a SAM7 MCU that emulates a mass storage device.

Whenever the application detects evil activities, all potentially secret data needs to be wiped from the chip. I know how to do this for the SRAM memory (just write zeroes/ones), but how do I ensure that no bit is left intact in the USB FIFO buffers? Further, can I clean both IN and OUT endpoint FIFOS? I currently run double-buffered endpoints for #1 and #2.