Penetration testing my apartment
Problem: It's 1:00am, in a town where you don't really know anyone, you're locked out of your apartment, and the only things you have on you are a cell phone and a toy RC helicopter (it has LED's that blink, I thought it would be cool to fly in the dark).
Objective: Gain entry to your dwelling without having to a) wake up the neighbor or b) explain to a cop that your ID is just behind the door you're trying to jimmy.
Creating an encrypted volume
I needed to meet my company's required security policy for taking source code offsite: 256bit AES encryption.
Since the source code I had on my laptop was within a Virtual Machine, I thought it would be a good solution to make an encrypted filesystem big enough for the VM, and only mount it when I wanted to work.
Here's my requirements:
- Encrypted FS that is (un)mountable whenever need be
- Passphrase to mount the filesystem
- 30GB of storage within the filesystem, to accomodate the 30GB VM disk.
Wiping a hard drive
Wiping a HardDrive is a common task at the workplace or whenever you're getting ready to sell a PC. There is a utility to do just such a thing in almost all Linux Bootdisks called shred.
Shred can be used to wipe files, or whole drives. To wipe a drive, the following parameters are good to know
-z After shredding, one more pass will be made to write all zeros to the drive, not necessary, but it hides the fact that the disk has been shredded
-v Display messages about progress, which is handy since shredding a drive takes a fair deal of time
-n x x is the number of passes you wish to make. 3 is a good number, and if you use the -z option it will be 3 shredding passes followed by a 4th pass to zero out all the data
Put it together and pass it a drive to wipe:
shred -zvn 3 /dev/sda
And voila, all your private data goes bye-bye