Schneier on Security

Clive Robinson • November 26, 2009 8:23 PM

@ Arturo Bates,

“The pager address could be hidden — since pagers are a broadcast medium, one could just send a message to any random number in the correct city”

Yes it could and I designed a broadcast model to do exactly that for a broadcast data network.

The problem is that for Joe Avarage it’s not currently possible because of your assumption of,

“the target pager, listening in promiscuous mode”

Although pagers do decode all messages and are thus already in promiscuous mode, the firmware/software in the pager ignores incorect ID messages. So Joe Average does not get to see what are effectivly “random” ID messages.

Although technicaly it is not an overly onerous problem to resolve (use one ID in the same way as the IP subnet broadcast address) you run smack into “backwards compatability” issues using random ID’s.

Clive Robinson • November 27, 2009 5:07 AM

@ JonS, Trichinosis USA,

Irrespective of what you guys feel, the “truth” of 9/11 will probably not ever be known (and probably cannot).

All that can be known is verifiable facts, the rest is “perspective” and “interpretation”.

Even verifiable facts have issues.

For instance, take a fact such as a visable effect of a fireball/flash. In many cases all you can say is the “burn rate” being above or below the speed of sound due to visable shock wave and colour of the residual smoke.

If however the fireball/flash is recorded by a camera of one form or another It is (sometimes) possible using more elabarate tests and having the original camera etc to build an aproximation of the light spectrum and thus work out some of the chemicals that where producing the fireball/flash.

However that does not always tell you much (see design of FAE/FAX using petro products).

For instance if I take a bag of ordinary fine partical cooking flour (such as cornflour) and fill the “air” in a room with it and supply a spark from touching two mains wires together you will get a fireball/flash.

You will be able to identify aproximately the fuel (flour but not which type), but you will not be able to tell how it mixed with the air in the room (ie by accident or design).

You could make some assumptions based on the locality such as in a “cake shop storeroom” or “office meeting room”. But at the end of the day they are not facts just interpretaions of the available facts.

Thus although some of the facts of 9/11 are known, the circumstances will always be subject to perspective and interpretation…

Clive Robinson • December 5, 2009 2:08 AM

@ Nimity,

With regards to the pentagon.

I’m just going to use what has been said on Bruce’s blog at some point or other.

Again seperate cause from effect.

What has been said is,

1, The (supposed) pilot could not fly a month before.

2, The (supposed) pilot was on a line up that would cause maximal damage.

3, The (supposed) pilot made a last minute change and ended up on the strongest part of the pentagon.

4, There is information that a possible explosion took place on the aircraft before it hit the pentagon.

Right lets have a look at this,

A, It might not have been one pilot.

We know that the pasangers in another aircraft stormed the cockpit, unfortunatly they did not succeed in saving themselves.

So there is a reasonable possability that the passengers on the pentagon plane did storm the cockpit and removed the supposed pilot from control.

Thus the sudden change at the last minute could have been an experianced pilot trying desperatly to avert a disaster.

Unfortunatly there is no available evidence I have yet seen to say if this happened or not.

B, The effect makes the pilot an ace.

Err no.

There is an assumption that the pilot knew which where the strong points and which where the week points of the pentagon.

That is a congecture bassed only on effects there is no evidence of cause there.

It is equally as likley that the (supposed) pilot had no idea as to which was the strong point or weak point of the building.

It is possible that there was an argument in the cockpit that he was going to miss and he or another of his cohort made a last minute correction to not miss.

The fact that the plane was on an approach to the weak part and ended up on the strong part could be nothing other than coincidence.

Thus arguing backwards from that the pilot made an ace manover is not a good idea.

And from that point argue it was a “government agent” willingly giving up his life to support a conspiracy to etc etc…

C, There are reports of an in flight explossion shortly before impact.

There are many explinations that could account for what was seen.

There is to little information presented to make anything of it.

For instance if witnessess say the saw a flash, it might just have been sunlight reflecting of the aircraft as it made a manover.

It could also have been a fuel explosion caused by a cable or other fault induced by the bad piloting and a sudden stressfull manover.

It could also have been a hand held surface to air missile.

I will go with the latter for a moment.

It has been said many times that the White house has people with hand held anti-aircraft missiles to protect the building from just such an aircraft attack.

If true then it is as likley that the same is true for the pentagon.

Any problem with what I have said so far?

Now I will build up a possible theory.

1, the pasangers realised what was likley to happen and stormed the cockpit.

2, One of the passangers was a pilot and took the controls.

3, The passanger tried to pull the aircraft out of it’s course towards the pentagon.

This might account for most of the things you have said.

4, a soldier at the pentagon armed with a missile fired to late to stop the aircraft.

5, The pilot failed to pull the aircraft out due to the missile taking out the flight controls.

6, on discovering that their own soldier was actually responsable for the aircraft crashing into the pentagon the authorities decided to cover it up.

Now you might ask why.

Well apart from embarsment there would have been a real public backlash. It would be “Publicaly known” that aircraft aproaching Gove buildings would be shot down.

The question would then arise where would it impact a public outcry would then ensue bassed on the “bleeting of a knowing sacrificial goat”.

This would then disunite the American people at a time of national crisis etc etc.

Now I’m not saying this happened but most would think it more likley than a “Government Agent” on a “Suicide Run” to promote some political agenda.

But then there is the question of motivation, what motivates any supposadly sane and rational person to fly an aircraft with a hundred people on it and many more on the ground to certain death…

As I said some time ago the true facts of 9/11 may never be known.

We can only guess at possabilities from the information available.

What we do know is information is not available due to a number of reasons. Arguing back from the effects when humans are involved does not get you back to the cause, as humans are unpredictable and have unknown motivations.

Occam’s razor does not work for anything other than inanimate objects (and not always then) when you have animate objects that can react to the environment you get great complexity which makes chaos theory look like 2+2. When the animate objects are sentient and can respond to motivation outside of the immediate time frame or environment then any and all bets are off. Any theory no matter how improbable has a chance (not probability) of being correct but 99.99…% of them will be wrong. The problem is science has no way of deciding.

Clive Robinson • December 5, 2009 4:04 PM

@ MarkH,

I see you understand the “cause <- effect” problem quite well which was the point of my comment.

One little thing,

“Clive doesn’t believe that Occam’s razor works for people”

Hmm I wouldn’t quite put it that way, I don’t think it can be counted on for anything more than guidence when humans are involved.

So I had better give a bit more of an explaination of my view point and why (though I suspect you broadly agree),

Occam’s Razor is the assumption that,

1,”on the available evidence” the
2,”simplest explanation” is
3,”most likley to be correct”.

Thus as an engineer I’m used to inanimate things following natural laws so I kind of assume bullet’s won’t fly around corners unless the hit something first. And I expect to find evidence on the bullet and on what it hit.

Thus if I find a bullet around one side of a corner and the gun around the other I assume the gun not the bullet was moved (unless the bullet is in what was an animate or easily movable object).

I would be unlikley to assume that someone had fired a shot into a water tank put the bullet in their pocket put the gun on the ground walked around the cornner and put the bullet on the ground etc, unless I had good reason (other information) to make it a “reasonable probability”.

However when you are dealing with animate objects they follow whatever path they chose for whatever reason and that may not be apparent to an investigator for a number of reasons.

That is you find a rat that died of a heart attack halfway up a drain. It could have been going about it’s “normal occasions” and just died, or a cat might have chased it up there and it died of fright.

The cat having not got fed etc moved off. Thus the only evidence at the scene says the rat was about it’s normal occasions, because the cat is nolonger there for the investigator to consider. So Occam’s Razor will fail due to lack of a particular piece of information, (unless the presence of a/the cat can be shown by some method).

With humans who are not just animate but sentient as well it is not just that the “motivator” (the cat etc) for their actions may no longer be at the scene it may never have been there ever, and the “motivator” may also be from a time frame significantly previous to the events at the scene.

For instance I give a lorry driver an order over the radio to go get something whilst they are on another job.

They crash on the way there, and as there is no paperwork, then there may be no evidence as to why the lorry is where it is at all.

Thus a lack of information available to the investigator prevent’s Occams Razor being applied correctly.

However instead of me giving orders to the driver, they may have seen something, which triggered a memory and they decide to act on it (like their wedding aniversary or childs birthday etc etc).
Further even if the investigator is aware of the “motivator” they do not know what weight the human gave to it (unless the human can say but then they may lie).

So the investigator can only give the “motivator” assumed values.

So it’s not that I don’t think Occam’s Razor can be applied to humans, I think it is only likley to work when they follow a statistical model (such as in the case of an emergancy etc) or all the information is available.

When premeditation is involved then all bets are off, as the chances are very high it will not work, as the criminal will use Occam’s Razor to give them an alibi etc.

Does that explain my point better?

Oh whilst I’m clarifing things I better say that the senario I posted was just an example to explain information presented nothing more than that. I don’t give it as anything other than showing that effects can be argued backwards to a different explaination.

I was also trying to come up with an alternative explanation that included as many of the pieces of the puzzle as had been presented whilst trying to keep within “reasonable probability” of similar events that have been given by others as known/belived to have happened on 9/11 as have been given on this blog.

And yes I can think of a whole load of other near equiprobable senarios and I don’t give them any credence either.

Because it’s the “reasonable probability” on “ALL information” that makes Occam’s Razzor work and we don’t know “ALL” the information nor are we likley to.