The Other End of Sunset

Monday, November 28, 2005

Random thoughts from the Thanksgiving holiday

Hello Fearless Reader, I have just returned from some time off to celebrate another Hallmark(tm) Holiday. This one? Thanksgiving.

I don't mind real holidays. I do mind fake ones. The ones that are generated largely to sell candy, cards, or toys.

But I won't dwell on that. Much.

I won't dwell on Hallmark Holidays because I promised one of the OtherEnders that I'd move away from the serious postings, and lean back towards irony on this post. Although I'm not sure I've made it to ironic yet.

(BTW, OtherEnders are those readers that talk to me about the posts. Few, but proud. And usually smarter than me.)

(BTW, 2, one of the OtherEnders always finds one or more grammar errors in my posts. Damn, Dave Cowan strikes again. And no, it's not Cowan who points them out.)

Although I will dwell, briefly, on Americans' love of fake history. Parson Weems' cherry tree (no, not George's). The traditional duck on Thanksgiving (nope, not turkey. Well, maybe, but not in mass). WMD in Iraq (oops, just a slip. Sorry.)

No, I won't dwell on our irrational need to turn humans into demigods. (I will, however, point you to Howard Zinn's A People's History of the United States.)

Rather I will spend some time talking about my non-work activities.

More specifically, I will talk about cryptography. And tattoos. Clearly there's a connection, right?

As long as humans have had language, they have had secrets. And as long as they had secrets, people had reason to try and hide them. And thus they created lots of ways to keep them. Chief among these ways was cryptography. Cryptography was made far more powerful by mathematics and information theory, but it didn't start there.

There is some evidence that early secrets were hidden in interesting ways. Such as by tattooing the secret on the shaved head of a slave, and then letting his hair grow back in. Hopefully, they weren't blond slaves, because then could one see the secret through the hair? Dunno. But anyway.

If you want to keep secrets, you need to worry about the entire context of the secret. How is it generated. How is it used. How is it stored. And how is it destroyed.

It's easy to do bad cryptography. History is littered with ciphers that seemed like good ideas, and were not. And it's even easier to create worse cryptosystems. The cryptosystem includes the cipher, and the people and processes that use it.

For example, when changing from one key to another, it's often a bad idea to send out the new keys in the old cipher. And it's usually a bad idea to have the same text in every message sent out in each new key set -- but the weather sometimes doesn't change from day to day. And it's almost always a bad idea to assume that your cipher mathematics will remain secret. Trust me, it won't. All these examples have happened. (David Kahn's The Codebreakers is a good read on the topic.)

There are really trivial ciphers in the world. In some twisted way, ROT13 is a cipher. (That sentence is a pun, by the way, but a quite poor one.) There are some good ciphers in the world (AES for one).

But as I mentioned, there are some old ciphers that aren't so good.

One of them is tattooed on my back.

For those of you who care, it's a 3-rotor, monoalphabetic cipher that dates back to the 16th century. And I wouldn't want to live on the cryptographic security. But that's ok, it would be hard to turn the rotors on my back anyway. But I digress.)

The process of getting a tattoo involves paying some person to stick a needle into your skin. Repeatedly. And did I mention that you are paying for this? Anyway.

In my case, the tattoo is basically line art, mostly in black, with relatively little color or fill. However it still took ~2 hours. And it sort of hurt.

It didn't hurt as much as I expected. In fact, about an hour in, I was more bothered by how incredibly bored I was. But it didn't always feel so good. There was a woman getting a tattoo in the next room (apparently it was a rose, anyway). Judging from her yelling, I guess hers hurt more.

In my case, I sat on a chair, backwards, leaned over a pillow, while the nice guy from Blue Star Tattoo drew on my back. (Did I mention this involves a needle?) Before he started jackhammering into my back, he took the image of the device, and redrew it into a clear stencil. This stencil was then copied in reverse onto a piece of inked paper and transferred onto my back. It kind of felt like the old days in school, when they had those stencil machines instead of copiers? (Yes, I'm older than you, and went to worse schools. Anyway.)

Once he started using the needle on me, it hurt for about 15 minutes. However, like magic, after about 15 minutes, the endorphins kicked in. By the end, when I stood up, I was a little dizzy from their effect. Wow. Wild.

After the artist finishes, the tattoo is bandaged up. The bandage stays on for a few hours. I didn't bleed very much at all, which surprised me, but... The coolest thing? When I clean the tattoo, I can feel the pattern in my skin. I think this is because it is swelling as it heals, but I still think it's cool.

And if I were just a little smarter, I could use the raised pattern that I can feel to encrypt my secrets, in a poor cipher, and leave them for you to find, and decrypt, in some taxi....