How do I securely overwrite files stored on a flash drive?
FreeOTFE Explorer includes (optional) functionality to overwrite files as they are moved into an encrypted volume, or on demand, to destroy plaintext (non-secured) copies. This works well for destroying files stored on a normal (magnetic) hard drives, however many flash drives employ “wear levelling” to reduce wear and prolong their useful life. This can cause overwrite data to be written to locations on the disk other than where the data to be overwritten is stored. As a consequence, most (if not all) file overwrite tools are not be able to overwrite files stored on such flash drives – even though it may report that they have operated successfully. To securely overwrite files on flash drives, please delete them as normal – and then overwrite all remaining free space available on the device. This will prevent any form of wear levelling from redirecting overwrite data to other parts of the disk, and guarantee a successful overwrite.
