Steganography, prevention before is better that detection after

New Scientist recently ran an article about steganography. If you don’t already know, steganography is essentially encryption with a difference. Specifically, encryption is usually obvious. It may be that the data Alice sends via email to Bob with public key cryptography is entirely secure from eves-dropping by Eve (pun intended, sorry), but Eve will know data is being sent that she might be interested in. Steganography, by contrast, seeks to hide the encrypted data so Eve is not aware of its very existence.

It’s a very ancient idea, stretching back to ancient Greece. In modern times a common way to perform the trick is to hide data in an image. One of my more gifted undergraduate students did a final year project on this with me. We used a known password as a seed for a pseudo-random number generator to determine which pixels of the image we would embed the data in. By playing with the least significant bit of one colour in randomly spaced pixels, you can very effectively hide data.

The New Scientist article suggests that if you detect the steganography, and if we obtain the computer of the suspect and if they have carelessly wiped the software, there might be traces that tell you this was done. Now let’s remember the whole point of steganography is that the first step is improbable, you most likely won’t detect it.

The issue is, in today’s geopolitical situation, reasonably serious. It has been suggested (see the wikipedia article I linked above), that such techniques were used to exchange data on site like ebay to plan major terrorist attacks. With lots of analysis software only playing with known algorithms, or relying on comparing modified images with the original (where the original may not be available) what can such a major website do to prevent such abuse? Well, I thought an approach would be to essentially employ the same techniques with random data. That is, randomly poking data into bits in pixels here and there will, up to a certain point, not affect image clarity to the naked eye, but unless the encrypted data is loaded with huge amounts of error correcting code, it will destroy the payload. You could easily automatically run such a filter over uploaded data. I’m sure similar approaches would work for digital sound.

Receiving Ukemi

For those not acquainted by martial arts. The title is a bit of a weak play on words, since “ukemi” means something like “receiving through the body”. Uke is generally the receiver of a technique and thus the attacker in aikido, whereas the nage is the thrower to use one possible word.

Ukemi is important in Aikido. You will spend literally half your training time attacking and then “receiving” the technique, and all of these aspects can be lumped under the title of ukemi. It’s a difficult balance to get right in aikido. It is learned in a very cooperative nature, and so the idea (for some) is be an “appropriate” attacker for each training partner, tailoring your attack to each. Thus, for a student on their first night, you might actually move the student’s arms to help them learn the “throw”.

Issues tend to arise more in pairings between non beginners. Some advocate that as an uke you can learn aikido by blending completely with the nage. I personally prefer an approach of attacking in a way I believe is probably appropriate for a “normal” attacker, and then protecting myself and blending in the aftermath. I’m probably slightly above average height, weight and strength and so a good model of an attacker, and perhaps somewhat harder to throw.

Having said that, I do not prevent people from throwing me. I just don’t strive to throw myself, blending so completely that every throw seems to “work” perfectly no matter what.

Recently I received a fair amount of verbal and non verbal (expressions and so on) criticism from a student of about a year’s experience about the “awkwardness” of my ukemi. I think in retrospect I should have indicated that unhelpful, non constructive criticism is as unpleasant and counterproductive for me as to anyone else. I did however, rather unhelpfully, suggest “you might want to consider that I am not the whole problem”. I was exasperated at the fact that this person thought I was trying to stop her from throwing me, when in fact I was trying to help her explore where things were going well and where they were not. The exasperation was not helped by my conviction (rightly or wrongly) that if I really wanted to stop her from throwing me, I could have done so very easily. (Yeah, I know you can always stop a known technique, I don’t mean that, really).

The reality is, there are very, very few people to whom I would give concerted “awkwardness” to stop them throwing me, and those are among the people whose aikido I respect the very most, and it would be something I would do rarely, and as a gift to that person (and because it can be a great deal of fun once you are comfortable with another person!). If you’re reading this, you know who you are! If I’m trying to be “awkward”, you’ll know about it.

When I hit 3rd Kyu (around the middle of the white belt grades), I took a decision I simply wasn’t going to worry about awkward ukes any more. It’s my problem to deal with the uke, not theirs. And now a good few years later (about nine) I find myself teaching Aikido, I emphasise this point to all the students in our club, and it’s very much our philosophy. Nevertheless, there are times I am training with another when I don’t “finish” a technique when I feel their ukemi doesn’t allow it. Those are times when I feel I would have to be profoundly unkind to do so, or potentially injure someone, especially when the person is (in my opinion) unaware of their own danger. Mostly however, I believe in the importance of finishing, providing I’m not putting my ego above the uke’s safety.

But I believe awkward (but realistic) ukemi is a gift to receive gratefully, that some people I train with, though I like them very much personally, are so intent on blending perfectly with everything I do before I do it, that I am deprived of a chance to learn from my mistakes. I suppose I should have, with humble sincerity, explained this to my training partner. Better luck next time.

Richard Feynman Lectures

I hold Richard Feynman in huge regard. He was a fascinating human being, a Nobel laureate physicist, his research in physics was second to none. But he was also a legendary lecturer, in both the fields of physics, and perhaps surprisingly computer science. And even more, he was an exceptionally well rounded person, a gifted artist, an amateur safe cracker and more besides. I own a copy of his lectures on Physics, bought for me by my Mum who felt (probably correctly) that no-one else would buy an item that sounded so boring, though it was on my Amazon wish list. (Incidentally, I think some pages touch on issues like the paradox I presented on crashing cars, I haven’t had the leisure to study this more closely).

Recently it was announced (and one of my students kindly wrote to tell me) that Bill Gates had bought up the rights to his lecturers and was making them available. I do praise Bill Gates for his philanthropy, and would have praised him for this, but regrettably, the lectures are only available with Silverlight, and so it’s another of a long line of Trojan horses to ensure we buy into a new proprietary standard from Microsoft. A huge shame.

In my last, marathon article, I talked a little about models of reality. A point I didn’t make is that we have trouble accepting that; no matter how much we dislike aspects of reality, they remain the same despite that. Feynman encapsulated this beautifully in this YouTube snippet of his QED lectures (which I had showed to my final year students). I have attempted a limited transcript below, but you should hear it in Feynman’s excellent good humoured Brooklyn accent for full effect.

And then there’s the … kind of thing which you don’t understand. Meaning “I don’t believe it, it’s crazy, it’s the kind of thing I won’t accept.”

Eh. The other part well… this kind, I hope you’ll come along with me and you’ll have to accept it because it’s the way nature works. If you want to know the way nature works, we looked at it, carefully, […unsure of this bit…] that’s the way it works.

You don’t like it…, go somewhere else!

To another universe! Where the rules are simpler, philosophically more pleasing, more psychologically easy. I can’t help it! OK! If I’m going to tell you honestly what the world looks like to the… human beings who have struggled as hard as they can to understand it, I can only tell you what it looks like.

And I cannot make it any simpler, I’m not going to do this, I’m not going to simplify it, and I’m not going to fake it. I’m not going to tell you it’s something like a ball bearing inside a spring, it isn’t.

So I’m going to tell you what it really is like, and if you don’t like it, that’s too bad.

If you’d like to hear more from this fascinating man, can I suggest more YouTube videos showing an old BBC interview with him:

  1. Part One
  2. Part Two
  3. Part Three
  4. Part Four
  5. Part Five
  6. Part Six

Models, Perception, Science, Religion, Martial Arts

This is quite a long and detailed article, if you have no vague interest in meta-physics or philosophy and associated ideas, it may hold little value for you. You have been warned!

I doubt that any human being lives directly in reality. None of us has an exact understanding of reality and generally I suspect that’s a good thing. Those human beings who are gifted with an ability to see reality more uncloaked often pay a heavy cost for that, you can see this from reading biographies of our greatest scientists and artists. So in fact, we compose models of reality in our mind. Actually our very brains use models to simplify the massive processing required from our senses, magicians exploit the limitation of these models all the time to entertain us. Martial artists can exploit them for self defence.

Models usually start off simply, along the principles of Occam’s Razor. So for example when we are young we observe the Sun rising and setting in the sky and we take it as the simplest, and reasonable explanation that the Sun is moving around the Earth and not the other way round. The stars appear as a fixed background that wheels around the Earth, reinforcing the idea of a geocentric universe. But they are not uniformly distributed, and now we hit a factor that can often run contrary to Occam’s razor; humanity’s ability to discern patterns in the environment. It’s an important ability, and lies at the heart of the innate mathematical ability that defines us a species as much as our gift of language. But it often misfires. It leads us to see agents where there are none, and we are predisposed to suspect and fear agents that are essentially like us – anthropomorphic. This is also, incidentally, the root of our fondness of conspiracy theories although the irony of that cartoon appealing to one agency about our intrinsic ability to perceive agency should be considered.

We begin to construct theories as to the distribution of the stars, and we prefer solutions of order and agency to randomness. So we see constellations, and we name them by appearance. But why do the stars look like these things? It must have a meaning, so we build stories bringing all of these things together. And then, we notice things that wander against the stellar background, and indeed today we still use the word planet, derived from the greek observation of this wandering. These must be great, special things. And to these we attach godhood. An increasingly, some might say ludicrously complex model of the world emerges.

This pattern was, of course, repeated across the world. In the western world we have been significantly shaped by the beliefs of the Egyptians, Jews, Greeks, Romans and the old Norse models of the world. Most of those where themselves derived from others. Each became progressively more complex and intricate as time progressed. Depending on your perspective, Christianity is often blamed or praised for being the greatest influence on our world model today in the west, but in fact I would argue that the Greeks have that dubious honour. And to illustrate how ideas from old models are often patently false but very hard to leave behind, many (perhaps you) still believe Aristotle that there are five senses when there are more and we still use words like “quintessential” without much thought as to what they actually meant. Indeed what we think of as Christianity today is heavily influenced by Greek philosophy.

The ideological battle within us between the simple and complex, rich models continued. Most of the world moved towards belief in a single God, laughing at old beliefs of many spirits or many gods. Without commenting on the validity of these religions, it’s worth noting that if for example we look at very early Christianity, it was a very simple model of the world. In the centuries that have followed more and more layers of tradition have been tacked on to make a richer, more complex cosmology. Every so often, a schism occurs and a faction tries to return to fundamental simplicity, but usually every branch continues to grow in complexity thereafter.

Returning to physics and meta-physics, for a time, we knew the Earth was a sphere, and then forgot again in favour of flatness as a simpler model. Many suspected the Earth was still round, and then apparently we discovered it (though of course we were mistaken in fact). But the idea of the geocentric universe was generally still very secure, as was our model of humanity being the very purpose of the universe itself.

When Galileo constructed his telescope he used it to look at the greatest planet in our Solar System, named after the greatest Roman God, Jupiter. He saw what anyone alive can see today with a cheap telescope or binoculars, up to four dots near the great planet. Sometimes not all these dots were visible. It was extremely difficult to understand what could be going on. If everything orbited the Earth then the motion of these dots must be exceptionally complicated. But there was a much simpler solution, that these were moons of Jupiter, orbiting the distant planet directly. Four moons, the largest of the numerous moons of Jupiter and still collectively named for Galileo today. To us, living within a well established (more accurate) model of the Solar System that we have today this seems of no consequence, but this is an example of that overused phrase a paradigm shift. In other words, it required Galileo to make that leap that the model of the world espoused by Aristotle was quite simply wrong. There is an enormous mental inertia to be overcome in such an act; we become very attached to our models, they are nothing short of our perception of the reality we exist in. Remember, one branch of the Christian church only pardoned Galileo for this “heresy” in 1992! But when we can and do embrace the improved model, other deepening of understanding can rapidly follow. So for example, once we accept that moons can directly orbit an entity other than the Earth, we begin to question all the assumptions of what goes around the Earth.

And so in a short time, we move from a model, that began so simply and became so complex, where the Sun, Moon, planets and stars revolve around our beloved Earth, to a much simpler model where only the Moon keeps us company in this way. There is massive resistance because of our huge investment in our model; and also because it diminishes us as a species, and our home. But when we accept the truth, or at least our improved model of it, we come to an understanding of the astonishing grandeur of the universe, so much greater than we could ever have believed before.

It’s happened again since of course, odd little inconsistencies in the Newtonian model of the universe emerged. The pattern observed by Kuhn appears again and again. We greatly resist the evidence against our current model. The model is again, our very perception of reality. Eventually the evidence mounts up so much that we can no longer ignore it; it has to be explained. The explanation that eventually comes is again, shattering intellectually to us. And in fact that is getting worse.

Specifically, most people still happily live with the Newtonian model of reality (even most scientists). That’s because it’s an astonishingly successful approximation to reality, it works brilliantly well in almost all situations. As I write, near the 40th anniversary of the Apollo 11 mission I should note that Newtonian mechanics alone were sufficient to land a man on the Moon. (Incidentally, note that the names of the missions that took us there, first Mercury, then Gemini, then Apollo in the great Saturn V rocket show how we drag our old obsolete models with us centuries later). However, we know the Newtonian model to be wrong. We know that General Relativity and Quantum Mechanics are better models, and unfortunately, they are not simpler. In fact they are so complex, we fight our mind and brain, evolved to understand a Newtonian world, as we try to encompass these theories.

And for the first time physicists are facing a shocking possible addition to reality, one that rocks them to the core in the same way the incompleteness theorem did for mathematicians. We may simply not have a sufficiently evolved brain to totally perceive reality. Perhaps all our models are such a simplification of reality that in the same way a dog cannot understand general relativity or quantum electro-dynamics, we shall never be able to understand the true Theory of Everything if it exists. Certainly it is harder than ever to train young humans to the summit of current understanding in their twenties, when their brains are still supple enough to probe reality (few great discoveries in science and mathematics were made by older people).

But suppose for a moment that the theory of everything exists, and is simple. Many people believe this would give us full predictive power over all the emergent behaviour that arises (i.e. literally everything, including love, music and art). Of course that doesn’t reckon with, just to begin with, chaos theory which actually doesn’t mean what most lay people think it means, especially since Jeff Goldblum propounded it in Jurassic Park in a way, that to me, sounded much more like the totally different catastrophe theory. (By the way, following that film, I have watched the total bemusement on the face of a kindly elder pure mathematics professor as he was asked by a prospective student if he was a “chaotician”.)

But actually, and coming to martial arts in this, the truth can often be safely hidden in plain view. Most of us will never find it or believe it. Note I include myself in “us”. As human beings, we actually love complexity and tradition and can’t accept simple truth any more than we can understand complex mind bending theories. For now, I set aside the fact that some will always use complexity and tradition to exploit us by hiding reality from us, it’s quite enough to deal with self-deception at the moment.

When a new student sits on the side of the mats watching an instructor demonstrate aikido (for the sake of argument) they are looking at two human beings with flawed models of reality attempting to do their best to demonstrate an underlying reality. No matter how hard they try, or what they know, it will not be perfect. They fight the interpretation of what the other is, what they are doing, what they themselves are and what they are doing. In his recently published memoirs Alan Ruddock discusses how the mental aspects of this for each of us are shown by analogy in the old Chinese book Journey to the West introduced to many of us by the Monkey TV series.

Add to this mix that the student, actually whether they are a beginner or not, views the whole proceedings through their own flawed model and perception. What they see is rarely (possibly never) what is exactly happening. Watching a particular “throw” the student can see a start with two people standing, and a finish with one lying on the ground. The arms are used to cause the throw to “happen” and so a very simple model is that the person still standing at the end essentially struck the other person to force them on the ground. I’ve watched this very process happen in a room filled with beginning students, who after witnessing a fluid gentle throw that brought no harm to the “victim”, proceed to stand with their equally inexperienced partner and more or less try to knock them onto the ground in a very crude approximation of the throw they watched.

So it is for beginners, but actually with experience it’s just the depth of the misconceptions that alters. For instance, person “Anne” throws person “Barry” while person “Clare” watches. Suppose to simplify things that Anne does a perfect (if such a thing exists) aikido throw on Barry who is gripping both of Anne’s wrists with his hands. She moves in complete harmony with Barry so well that Barry cannot resist and is thrown perfectly. As Anne moves – Barry, who is gripping her moves too – and his body position relative to hers changes, this in turn changes his grip and as a consequence he rotates Anne’s arms. Anne neither opposes nor amplifies this, she merely continues to move where she can till Barry loses his balance and falls.

But Clare, watching from the sidelines, knows it cannot be that simple. Anne must know a special trick or two. She has so much to watch. So much information to assimilate into her model: how Anne’s face moves, her arms, her legs. After all, Anne is “doing the throw” to Barry, so Anne must be doing the special things. She sees that Anne’s arms rotate as she performs the throw. She cannot possibly perceive that actually it is Barry that is doing this, and even if she could, even if her highly sophisticated mind could believe it, is is likely that the primitive model most of us have will prevent her from being able to accept it.

And so Clare learns to perform this throw by moving her arms. It’s a flawed model, but actually it may not be too far from the truth, so mainly it works. The times it doesn’t, well these are just aberrations that can be put down to other factors (just as Kuhn has observed in science). The longer Clare trains this way, the more deeply ingrained this flawed model becomes. She starts to tack on little adjustments that help correct for the times it diverges from reality. She learns a host of tricks to deal with times that this causes the “throw” to begin to fail, so she can “make it work”.

Perhaps one day Clare starts to teach others. She teaches them honestly, sincerely, as best as she can, but from a seriously flawed model. The model propagates to many other people. It’s an interesting example that memetics doesn’t guarantee that “good” memes or models of the world survive and prosper. The correct model Anne tried to demonstrate is astonishingly simple, much simpler than the one Clare has assimilated. But now, the intellectual investment Clare has made makes it unlikely that she will ever really see the true model. Worse yet, the model she has learned has crept into her every body movement. Even if she could somehow intellectually grasp the correct model, she must fight every “lower” part of her body to effect it.

Perhaps there can be seen here the parallels between these threads. That models spread rather like religions whatever their nature is. Loyalty to a personality or a concept can be laudable, but it can prevent people from questioning things for themselves, preferring to attach themselves to the models espoused by others. But however much we may respect another human being and attach value to their beliefs, I believe it’s our responsibility to ourselves, and to them, to remember that they are fundamentally like us, imperfect, doing the best they can. If they falsely believe something however sincerely and we come to believe it too out of loyalty, we only increase their attachment to their incorrect model, and the chance they will never move from it.

So again, even leaving aside the malevolent attempts by some people to deliberately deceive ourselves (and a yet deeper discussion would examine our beliefs about such motivations as we are predisposed to see malevolence where there is none), our very nature is our greatest enemy. We resist perceiving reality as it really is, we each have rival models of reality which leads us to clash with each other when we “cannot see things from each other’s point of view”. We literally cannot. We naturally embellish models to make them more complex than they need to be, we enjoy it. We struggle to believe things could be simple. We often conflate the ideas of “simple” and “easy”. Simple things can be hard to do.

All we can do is make a massive effort to see things as they are, as individuals, or as as close as we can. In the Japanese martial arts, we would say that we should strive for shoshin, “beginner’s mind”. We need to constantly challenge our assumptions about the world and other people. In many senses it’s a very Buddhist philosophy. It’s arguable whether it is always an act of kindness to help others refine their models. It may be, in extreme cases, an act of violence to attempt to wrest someone from a model they are so deeply attached to. And yet some of those models can themselves be damaging to the individuals that hold them and those around them. Few would argue that attempting to refine the model of a man who despises and may injure people of a given race because of his deeply but incorrectly held views would be a bad thing. But incorrect can be a hard thing to judge. None of us is perfect, none of us perceives reality as it is. Is it right for an atheist who is absolutely convinced of the absence of a God to try and disturb the world model of a terminally ill believer who derives much happiness from their model, whether it is correct or not?