Brian D. Buckley

Sorry for the lack of postage yesterday. Not sorry like an apology, of course; sorry as in, you were deprived of my genius for twenty-four hours, and I’m sympathetic to that. 😉 (When you have so much homework you have to take the morning off your day job just to get it done, the blogging doesn’t quite happen.)

But I had my final exam last night, which means no class for a few weeks, and a short chance to breathe.

*breathes*

Yeah, that’s the stuff.

So I’ve been getting into Celtic knots lately, doodling them in my notebook margins all semester. Thought I’d share a few…

This one’s called a Trinity knot, or triquetra:

A little pudgy…

Somewhat better, still kind of skewed. Also, floating in a wheel of fire?

Not sure what this one’s “official” name is, but I call it the Quad. Sort of a variation on the Trinity.

Like the Olympic rings got sucked into a black hole…

Don’t know the name for this one either, but it pops up a lot if you google Celtic knots.

I did take actual notes in this class, I promise.

You might also recognize it from the beginning of Dark Knight Rises:

As you can see, they blatantly stole their logo from my computer science notebook.

This one, the Eternity Knot, is actually a Buddhist symbol rather than a Celtic one.

Eternal. Tiny, but eternal.

Infinity x2

Most knots aren’t just a single enclosed picture, but can be extended linearly as long as you want. I’m running out of time this morning, so I’ll just post the rest of the pictures without the commentary:

Do you doodle in your notebooks? What kind of things do you like to draw?

Maybe you want to start a journal, but you don’t want your brother to read it. Maybe you’re corresponding with spies in Luxembourg. We all have our reasons for wanting secrecy. But how do you hide a file on your computer so nobody else can find it?

You could change its properties to Hidden, but that’s not very secure – anyone can go into Folder Options and set Windows Explorer to show all hidden files all the time. Or you could bury it deep in a bunch of folders, but someone could still find it by searching. How do you keep a file really, really secret?

If you’re on a Windows computer, try this. Click Start, then Run. Type “cmd” in the box and click OK. Now you’re at a command line. It should look something like this:

(If these screenshots are a little hard to see, you can click them for a slightly bigger view.)

In this command line, the part before the “>” tells you where on the computer you are right now. If you want to go to a different file path, just type “cd”, space, and then the new file path you want, and hit Enter. (“cd” stands for “change directory.”) Like this:

Once you’re in the place you want, you can use the command line to create a new text file in Notepad. Just type “notepad”, space, and then the name of the file you want to create. It’ll ask if you want to create it. Say yes. Bam, there’s your new text file, open in Notepad.

Okay, close the Notepad window.

So far we haven’t done anything too exciting – we just created a regular text file. But now we’re going to hide another text file inside of this first one. How?

Simple. Go back to your command line, and type in “notepad newfile.txt:secret.txt”

Of course, if you called your original text file something besides newfile.txt, you’ll use that file name instead. And your secret file doesn’t have to be called secret.txt. You can call it anything you want. The main thing is to put the plain-view file’s name first, then a colon, then your secret file’s name.

Once again, it’ll ask if you want to create the new file. Say yes. Now you have a new Notepad window open, and it looks like this:

Notice the file name at the top: “newfile.txt:secret.txt”. We’ve got our secret text file open.

Type anything you want in here. Save it and close it. Now take a look in your folder. What do you see?

Just newfile.txt – no sign of its secret sister. But you can always open it again with the same command you used to make it in the first place, “notepad newfile.txt:secret.txt”.

Now, if you do a search on this folder, none of the contents of secret.txt will show up in the results. In fact, if you look at the file size of newfile.txt, it only reflects the size of newfile’s contents. Secret.txt could be as huge as you want, but you’d never know it. (By the way, this technique is called “Alternate Data Streams” – google that if you want to learn more.)

Nothing is 100% secret, of course. If somebody knows what they’re doing, they can track down these secret files too. But you have to know what you’re doing, and you have to be specifically looking for them. I work in IT, and I mentioned this technique to several of my co-workers. None of them had heard of it, or knew how to find the hidden file.

One word of warning: if someone deletes newfile.txt, then secret.txt will be gone too. Just so you know.

Did this make sense? If you tried it, did it work? Anybody have any questions?

Do you think you’d ever use something like this?

Bards, that erst sublimely told
Heroic deeds, and sang of fate,
With fervour seize their adamantine lyres,
Whose chords are solid rays, and twinkle radiant fires.

-John Keats
from “Ode to Apollo”

I’ve decided: it’s going to be a good week.

We may not all agree on whether robots have souls, but one fact is beyond doubt: your computer files have an afterlife.

Say you’re using Windows and you have a Word document saved on your hard drive. Recipe for sweet pickle casserole from your Aunt Mindy. You hate sweet pickles, and Aunt Mindy’s visit is over (finally!), so you decide to get rid of the document.

You select the icon and press Delete. Is it gone? Not yet, of course. It’s in the Recycle Bin.

Ok, you empty your Recycle Bin. Now is the file gone? Nope. You can’t access it anymore, but it’s still there.

See, Windows keeps a record of all the files on your system and where they’re located, and that record is separate from the file data itself. When you delete a file, it just removes the record of the file, changing the status of that space from “in use” to “available.” The actual data is still there, completely intact.

By the way, this isn’t some sinister plot hatched by Microsoft to immortalize sweet pickle casserole. Nearly all operating systems do something similar. It’s not about privacy, it’s about efficiency. Deleting only the records of the file is much quicker than deleting the file itself – and most people think their computers are slow enough as it is.

Time goes by. Since the recipe data is marked as gone, Windows may overwrite that data in the future. It may be gone just a few minutes later. Then again, it might not. How long could it last? Hours. Weeks. Decades. It all depends. And even if part of the file is overwritten, the fragments that remain can still be recovered, examined, and possibly reassembled.

Instead of just deleting that one file, let’s say you completely reformat your hard drive. Clean slate, everything gone. Right?

You can probably see where this is going. Even reformatting your hard drive is more of a bookkeeping exercise than anything else. It still doesn’t scrub clean the actual data.

This applies not just to hard drives, but to USB flash drives as well. So if you let your friend borrow your flash drive for the weekend, he could – theoretically, if he wanted to, if he knew how – he could look at not just the files you meant for him to see, but many of the files you’ve deleted from the device over the the last few weeks, months, years. He could copy them onto his own computer, and you’d never even know.

How? There are lots of tools out there – many free, and many others cheap. Active@ File Recovery is one I’ve used myself with great success – the trial version is free, and the full version is something like $30. Of course, my own intentions were less nefarious. I was trying to recover data from one of my own hard drives that had died years ago. (I was very successful, too.) But it’s worth keeping in mind that such tools exist, in case you ever save any files with data more sensitive than a casserole recipe.

So how do you clear out those old, deleted files? One method (in Windows, at least) is to use the “cipher” command. Detailed documentation on “cipher” is here. I haven’t tried it myself yet, so if you go down that road, do it with caution. And even if you do completely delete the data, some information remains. The Windows Registry stores vast troves of metadata about your activities, including a list of recently accessed documents. That doesn’t apply to the flash drive scenario, but it’s still something to keep in mind.

Should you be worried about any of this? Eh. Not necessarily. Sure, people can violate your privacy with computers, but then people can do all kinds of terrible and complicated things. That’s just part of living in a society, and it’s been true for centuries. You trust some, you get burned occasionally, and life goes on. Nevertheless, I think it’s good to at least be aware that deleted files do not disappear.

I’m taking a digital forensics class right now, which is my source for a lot of what I’m telling you. If you have any questions about this, or any other digital forensics topic, ask me in the comments. I’m far from an expert, but I’ll do my best to answer.

Who was up till after midnight last night finishing their research paper? I’ll give you two guesses, and the first one doesn’t count.

Another of my high school masterpieces. Enjoy. Barring an international incident, regular posts return tomorrow.

What’s been keeping you busy lately?

Good morning, hypothetical reader!

I got up at the more-ungodly-than-usual hour of 5 AM today, and I’ll be heading out before 6 to get to a meeting in Detroit at 8. Besides which I had class until 8:45 PM last night, and I have a paper to finish tonight. All of which means: no post today.

Instead, please enjoy this animated gif I made way back in my freshman year of high school, when I was in my “Hey animated gifs are super cool” phase and I made them frame by frame in MS Paint.

(Who am I kidding? I still think animated gifs are super cool.)

Have a great day!