The first time you start to involve yourself in cryptography you start on a path to suspicion and paranoia. Nearly every discussion about cryptography involves two example parties, Alice and Bob. Alice is always trying to keep secrets from Bob, and these two characters are used to illustrate everything from public key cryptography to man-in-the-middle attacks, and a lot more than just these examples as well.

This entire line of reasoning starts to kindle thoughts about how you go about your everyday life and just how much of your personal data, your privacy, your secrets are all leaking out around the edges. For all the efforts of your own personal Alice, there is a Bob out there, maybe, trying to dig up things you aren’t watching over or never expect.

A portion of cryptography, or more generally espionage in general comes down to the things you leave behind. Some folks think that strip-shredding sensitive papers is enough, while others consider upgrading to crosscut shredding to be the gold standard. For really sensitive papers, I personally have considered the only really effective way to prevent them from being reassembled is through burning and beating with some sort of implement to mix up the ashes. All this is to prevent information from leaking out where you never intend for it to leak out from. A big part of this, and in a lot of film noir detective stories, is phone numbers or passwords written on sticky notes or on a notepad. Sometimes people will write something down on a series-bound stack of papers with something like a ball-point pen, because it’s handy. The ball-point does put ink on paper, but it also can emboss paper below the sheet you are working on, and with a gentle swipe of pencil graphite, the ghost of what was written re-appears.

While I’ve been working at my desk, I got to thinking about convenient surfaces that I could take notes on, which would be handy and easily erased and reused. A while back I stopped at the dollar store and got a nice little whiteboard and a selection of dry-erase markers. Super cheap, super convenient. The whiteboard has proven to be very convenient and useful in my workplace and for $2, a non-issue when it comes to the pricetag. It struck me that this cheap cardboard and plastic whiteboard assembly could also be a very secure way to write temporary notes, say banking details for example. I can write a whole line of values and account numbers, passwords, whatever I like and with a swipe and rub of an eraser rag, whoosh, all of the details are gone forever. As I examined the whiteboard and considered this, I thought of ways that the wiping process could be reversed. There is no embossing onto a lower layer to worry about, and there doesn’t appear to be any order of anything at all on the surface or the wiping rag. So I would at least think on the outset that a whiteboard makes a very fine and secure temporary notepad to write anything on, because once wiped off, perhaps also with alcohol or Windex just to be very careful, I can’t imagine there is any way to unwind the clock on the erasure process. No way to get back what was written.

Now there is no application for this sort of security in my life, other than perhaps writing down account numbers, my SSN, or perhaps the password to some sort of system here at work, but if you are looking for a way to write temporary notes and not have to worry about security – a whiteboard at the dollar store certainly seems to be a solid approach.