app-crypt/bcwipe (1.9.8): Secure file removal utility
app-crypt/nwipe ((~)0.14): Securely erase disks using a variety of recognized methods
app-misc/wipe (2.3.1): Secure file wiping utility based on Peter Gutman's patterns
sys-fs/zerofree (1.0.3): Zero's out all free space on a filesystem