HDD Encryption/Decryption

GEOM bswap16

• Swaps bytes in every 16-bit word
• Similar to dm-bswap16 on Linux.
• The kernel module needs a user-space GEOM counterpart, a shared library which is loaded and used by geom application to send commands to the kernel part.

http://gitorious.ps3dev.net/ps3freebsd/geom-bswap16

http://gitorious.ps3dev.net/ps3freebsd/geom-bswap16-lib

Test

# UI shared library for GEOM bswap16

cp geom_bswap16.so /lib/geom

# Load kernel module

kldload geom_bswap16.ko

# Create a memory block device for testing

mdconfig -a -t vnode -f ~/test.bin -u 0

# Create /dev/md0.bswap16

geom bswap16 create /dev/md0

hexdump -C /dev/md0

00000000  bb aa dd cc 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000020  ee ff 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000030  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00100000

hexdump -C /dev/md0.bswap16

00000000  aa bb cc dd 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000020  ff ee 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000030  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00100000

geom bswap16 destroy md0.bswap16

mdconfig -d -u 0

Links

• https://www.dan.me.uk/blog/2012/05/05/full-disk-encryption-in-freebsd-9-x-well-almost/