This is possible with secure hardware and similar that refuse to run code that is not digitally signed by the real master
No, even that will be defeated. The digital signature is checked only once (it would be ridiculous to re-check it, say, before executing each instruction). There's a billion different ways you can take advantage of this. Say, for example, some code is loaded into RAM and its signature is checked. Now, all you have to do is replace the "validated" program with your own code in RAM. Supposedly the OS won't allow you to do this. So you create a device, kind of like a Game Genie, and you plug that into the DIMM slot, and plug the DIMM into it. Call it a RAM Genie if you want. The RAM Genie will twiddle the bits, either directly in the DIMM, or as the electrical signals pass through it. Wham, untrusted code is executing.
The only way to prevent something like that is to make it impossible for the user to modify the hardware. Even if the RAM is built onto the board, there are these people called "electrical engineers" who will easily figure out how to get around it.
Finally, someone who actually understands the complexity of this, even if you aren't quite agreeing with me...
The system of 7 equations you mention would more than likely be highly chaotic, meaning the results would be meaningless unless the initial conditions were known to extremely high accuracy. Of course this depends on the Lyapunov exponent of the specific system. I think we're wandering off into irrelevant territory here.
I think what is ticking me off is hearing people say "High school physics disproves this," wildly assuming that high school physics is not oversimplified and actually describes all possible scenarios. I wish these people would wake up and realize that "high school physics" is to physics as integer arithmetic is to mathematics...
Since everyone seems to think this is just "basic physics," let's actually work this out. The foam is going to be accelerated by several things: the aerodynamic drag due to its velocity through the atmosphere, the force of its own weight, and the acceleration of the shuttle (we can treat the shuttle as moving at constant velocity, and add its acceleration to the foam, and achieve the same numerical results).
Formula for drag force: D=1/2*C*p*A*v^2. C is coeff. of drag of foam, p is air density, A is foam cross section, v is velocity of foam. Over the short distance in which the event occurred we can treat p as constant.
Formula for acceleration of foam: a=-D/m-g-S, S is shuttle acceleration, m is mass of foam.
Substituting eq1 into eq2, a=-1/2*C*p*A*v^2/m-g-s.
Rewrite in differential form: v'(t)=-1/2*C*p*A*v(t)^2/m-g-s.
Solve the differential equation for v(t): v(t) = tan(1/2*(-t*(m*(g+S)*C*p*A)^(1/2)+arctan(1/2*v0*C* p*A*2^(1/2)/(m*(g+S)*C*p*A)^(1/2))*m*2^(1/2))*2^(1/2)/m)/C/p/A*2^(1/2)*(m*(g+S)*C*p*A)^(1/
2).
Integrate to find x(t): x(t) = (-m*ln(1+tan(1/2*(-t*(m*(g+S)*C*p*A)^(1/2)+arctan( 1/2*v0*C*p*A*2^(1/2)/(m*(g+S)*C*p*A)^(1/2))*m*2^(1/2))*2^(1/2)/m)^2)+x0*C*p*A)/C/p/A
I don't know about you, but that doesn't exactly seem "basic" to me. The only reason I was able to come up with it is I have a program (Maple) that can integrate and solve differential equations for me.
It's a fairly simple matter of plugging the in the right values for m, g, S, C, p, A, v0, and x0, and we'll settle this right now. If anyone knows what those numbers are I invite you to share them.
I'm giving up at this point, as your already consdering the shuttles velocity a variable in this equation.
Umm.. The upward velocity of the shuttle gives the upward velocity of the foam at the moment of seperation, which plugs into the equation D=1/2*C*p*A*v^2, to give the aerodynamic drag on the foam. Exactly how is that not relevant? Notice that the drag depends on the square of the velocity. Then you plug that into a=D/m+g+S where g is the acceleration of gravity and S is the shuttle's upward acceleration. Rewrite in differential form and integrate to get a damn good model of how fast the foam was traveling at each point along its fall. Maple can do it in a jiffy.
If you'll just give me the correct values of C, A, S, starting altitude, and air temperature, I'll work it out for you right here. I doubt you'll have more success in obtaining those numbers than I have.
Or are you gonna cut us off here before I prove you wrong?
I'd be more than happy to work it out for you right here, if I had access to the correct numbers (exact altitude at which it happened, average cross section of foam, exact speed of shuttle, etc.) Unfortunately I can't get them.
What I can do, however, is look at the video footage. It's pretty easy to calculate how fast the foam was moving if you make a single assumption -- that the acceleration was constant. It's easy to count frames, and NASA knows how long their own shuttle is. I don't understand why people are disputing something that can easily be verified by anyone who looks at the video footage.
If everyone did physics like you did (take guess, scratch head, flip coin, decide whether guess is correct), I think we'd be into the neighboring galaxies by now!
... is seeing how a bunch of geeks on some website can criticize the physics knowledge of a bunch of rocket scientists. Before you start quoting various "disasters," remember that one of them was caused by a failure to convert units (some engineers made a dumb mistake), and the other was caused by an acceleration-sensitive switch having a weak spring, and therefore triggering too early. Both of these were engineering mistakes.
These people are capable of launching a spacecraft from a planet whipping around the sun, through continuously changing gravitational fields, for hundreds of millions of miles, and put it down on a spot the width of your city park. They know physics. To put it bluntly, these people are badasses. The last thing they deserve right now is the intellectual equivalent of a 2 year old arguing over politics with Kofi Annan...
Yeah. You neglected the gigantic fricken' wind blowing past the shuttle. It was flying upward at 1000+ MPH after all. From the piece of foam's perspective, it was being blasted by a 1000 MPH wind. That tends to accelerate stuff.
It's getting really tiring going over this again and again...
The shuttle was hurtling upward at 1000 MPH. That means that, from the shuttle's perspective, a 1000 MPH wind was blowing past. It's quite easy to imagine how a 1000 MPH wind could accelerate a light piece of foam to 500 MPH in the short distance it fell.
Really, I don't see why this is so hard to understand. When you go 60 MPH on a jetski, your eyelids peel back. It isn't because you're accelerating, it's because your going really fast through the air.
The explanation of MHz I've always used is: "That's the number of numbers the computer can add together in a single second." Making some generous assumptions (addition takes one cycle, no cache misses), this is accurate.
Honestly, are any of us geeks ever willing to admit that we don't inherently recognize and grok every single term that is thrown our way?
I admit it when it happens. I also have the ability to learn pretty much everything relevant about the technology within about 15 minutes (there's this thing called the Internet), so I don't see why it should be embarrassing to admit initial ignorance. I still don't know what the hell SOAP stands for, because I just don't use it. If I had to, I could learn about it in a few minutes. I think most geeks are the same, but many have ego problems that prevent them from admitting ignorance.
At least with my bosses at work, I find that honesty about your knowledge base is always preferrable to spewing BS. You'll get tangled in your own BS pretty quickly.
No matter how widespread cars have become, a lot of people still don't know what a distributor is, or what the difference is between a carbureted engine and a fuel-injected one, or even the difference between diesel and gasoline. You won't learn these things in Driver's Ed -- you'll learn them in shop -- neither is strictly mandatory (D.E. might be, depending where you live). How would you feel if you were forced to learn all the details and workings of your car's engine? In the same way, it will never be mandatory to take a class that teaches computer terminology. I'll bet you $50 right now. Don't confuse a "Word processing and spreadsheets" class with an actual class teaching computer guts.
(and if you mention WMD or politics here, you should get modded down to obliteration)
I don't see why. I think it's genuinely interesting that the Bush administration was able to take over another country based on claimed evidence held behind its back, and get away with it (and now that it's coming out publically that there isn't much evidence for WMD in Iraq, the public seems to really not care), and now Darl seems to be doing the same thing. I wonder if he learned from example?
Why should the possible ideological connection between the two events be considered irrelevant, or "modded down to obliteration?"
Considering that Brian Kernighan, co-inventor of the C language, advocates this coding style in his book The Practice of Programming, I think it might be you who's the moron (and the 12 year old). This is a classic error that thousands of programmers have made and continue to make. It's the difference of a single repeated keystroke.
Why legislate, when we can innovate? Instead of wasting taxpayer money enforcing new laws and red tape, why not let the capitalist market come up with a technological solution to the spam problem? Not only would we avoid giving even more power to the government, we'd stimulate innovation and competition among anti-spam companies.
Is everyone seriously so impatient to solve the spam problem that they are willing to enact badly worded, overbroad legislation? Give the congress the power to regulate some aspects of the Internet, and that power will quickly expand into other areas. Do we actually want to go down that nightmare path?
Q: "Mr. Senator, how do you plan to pay for the execution of these new spam laws?"
Regardless of whether German law, or US law, or any other law, the liability concern raises an interesting point. The GPL states in part (5): You are not required to accept this License, since you have not
signed it. However, nothing else grants you permission to modify or
distribute the Program or its derivative works. These actions are
prohibited by law if you do not accept this License. Therefore, by
modifying or distributing the Program (or any work based on the
Program), you indicate your acceptance of this License to do so, and
all its terms and conditions for copying, distributing or modifying
the Program or works based on it.
That seems to be saying that it's still okay to use the software even if I don't accept the license. But if I don't accept the license, then there's no disclaimer of liability, right? So in theory could I sue a GPL author for damages as long as I haven't modified and/or distributed the program?
The point here, and I agree with the S.C. on this, is that Hamidi did not cause damage to Intel's computer systems. The basis of the suit was electronic trespass which compromised Intel's communications network. Clearly, Hamidi's actions didn't damage any equipment, they simply annoyed a lot of people.
From the article: "The consequential economic damage Intel claims to have suffered, i.e., loss of productivity caused by employees reading and reacting to Hamidi's messages and company efforts to block the messages, is not an injury to the company's interest in its computers -- which worked as intended and were unharmed by the communications -- any more than the personal distress caused by reading an unpleasant letter would be an injury to the recipient's mailbox, or the loss of privacy caused by an intrusive telephone call would be an injury to the recipient's telephone equipment."
Precisely correct.
Intel should have charged him with some form of harrassment. They picked the wrong charge, which was obviously bogus to begin with. For the S.C. to side with Intel on this would have set a terrible and incorrect precedent.
Not that I particularly agree with Hamidi's actions, but this ruling makes sense IMHO.
This seems to be a trend, as I'm sure y'all have noticed already: announce the latest in a series of movies, and simultaneously release a boxed set of DVDs of all the previous movies.
"The final blow occurred in 1983, when Adam Osborne boasted about an upcoming product months before it could be released, killing demand for the company's existing products... Unsold inventory piled up and OCC declared bankrupcy on September 13 1983. This marketing blunder came to be known as "Osborneing" and the phrase circulated in Silicon Valley for the next decade."
If I knew my gold plated box set was going to be an incomplete box set in two years, I would not buy it.
I don't know about this technology specifically, but off the top of my head, I would assume that they are using a lower frequency of X ray radiation (lower voltage in the X ray tube).
Traditional X rays work by passing through the body and are literally absorbed by dense material like bone. The resulting image shows regions of high X ray absorption. The reason it works is because the X rays have high enough energy to penetrate the body and come out the other side (except, of course, for where they are absorbed, which is the entire point).
This new technique works by scattering the X rays off the surface of the body. It detects metal objects because they interact strongly with X rays. In a sense it is operating on the reverse principle -- instead of looking for where the X rays are absorbed, it is looking for where they are strongly reflected. It must be that they are using a lower X ray energy, otherwise the X rays would penetrate, not get reflected.
I wouldn't go so far as to say the technology is safe, but the entire point is for the X rays to reflect, i.e., not get absorbed. It's probably safer than a traditional X ray.
Who knows what is an "executable file?" Suppose you have some program called Moronic SongWriter, and it is registered to the.MSW extension. Further, suppose Moronic SongWriter has a buffer overflow that can be exploited with a specially crafted.MSW file.
Someone attaches an evil.MSW file to an email, and sends it to you. Even though the.MSW itself isn't executable, the application will load it, get exploited, and execute the code -- virus, trojan, backdoor, whatever it is.
Just because it doesn't end with EXE, DLL, PIF, SCR, or some other common executable extension doesn't mean it's harmless. Unless you can trust every app on your system which is registered to some file extension, then those kinds of files can potentially be viruses.
So what? Sometimes companies are founded around a technology. Some people come up with an idea, think "Hey, this could be big," so they patent it. Then they organize and start up a company.
If people like you'd just start admitting that he's right and that GNU, like Linux, is an important part of GNU/Linux systems, and that FSF did do a lot for the whole OSS community, he wouldn't have to repeat it over and over again.
Yes, us poor, stupid individuals don't correctly appreciate his stellar, godlike contributions. We must be reminded of what a great man he is.
If RMS sat down and shut up, I might respect him. No one likes a loud mouthed bad mannered pedant, even if he's "right." Except fellow loud mouthed bad mannered pedants, I assume.
If I could, I would challenge RMS to write a book about the genesis of GNU, without ever using the words "I" or "me." I bet he couldn't do it.
I found a copy of the final draft online: Learning Spam: Simple techniques for freely-available software. The paper covers several machine learning techniques. The particular one I'm talking about here is the information-theoretic clustering and neural network approach.
Slashdot Mirror
No, even that will be defeated. The digital signature is checked only once (it would be ridiculous to re-check it, say, before executing each instruction). There's a billion different ways you can take advantage of this. Say, for example, some code is loaded into RAM and its signature is checked. Now, all you have to do is replace the "validated" program with your own code in RAM. Supposedly the OS won't allow you to do this. So you create a device, kind of like a Game Genie, and you plug that into the DIMM slot, and plug the DIMM into it. Call it a RAM Genie if you want. The RAM Genie will twiddle the bits, either directly in the DIMM, or as the electrical signals pass through it. Wham, untrusted code is executing.
The only way to prevent something like that is to make it impossible for the user to modify the hardware. Even if the RAM is built onto the board, there are these people called "electrical engineers" who will easily figure out how to get around it.
The whole damn DRM exercise is pointless.
The system of 7 equations you mention would more than likely be highly chaotic, meaning the results would be meaningless unless the initial conditions were known to extremely high accuracy. Of course this depends on the Lyapunov exponent of the specific system. I think we're wandering off into irrelevant territory here.
I think what is ticking me off is hearing people say "High school physics disproves this," wildly assuming that high school physics is not oversimplified and actually describes all possible scenarios. I wish these people would wake up and realize that "high school physics" is to physics as integer arithmetic is to mathematics...
Formula for drag force: D=1/2*C*p*A*v^2. C is coeff. of drag of foam, p is air density, A is foam cross section, v is velocity of foam. Over the short distance in which the event occurred we can treat p as constant.
Formula for acceleration of foam: a=-D/m-g-S, S is shuttle acceleration, m is mass of foam.
Substituting eq1 into eq2, a=-1/2*C*p*A*v^2/m-g-s.
Rewrite in differential form: v'(t)=-1/2*C*p*A*v(t)^2/m-g-s.
Solve the differential equation for v(t): v(t) = tan(1/2*(-t*(m*(g+S)*C*p*A)^(1/2)+arctan(1/2*v0*C* p*A*2^(1/2)/(m*(g+S)*C*p*A)^(1/2))*m*2^(1/2))*2^(1 /2)/m)/C/p/A*2^(1/2)*(m*(g+S)*C*p*A)^(1/
2).
Integrate to find x(t): x(t) = (-m*ln(1+tan(1/2*(-t*(m*(g+S)*C*p*A)^(1/2)+arctan( 1/2*v0*C*p*A*2^(1/2)/(m*(g+S)*C*p*A)^(1/2))*m*2^(1 /2))*2^(1/2)/m)^2)+x0*C*p*A)/C/p/A
I don't know about you, but that doesn't exactly seem "basic" to me. The only reason I was able to come up with it is I have a program (Maple) that can integrate and solve differential equations for me. It's a fairly simple matter of plugging the in the right values for m, g, S, C, p, A, v0, and x0, and we'll settle this right now. If anyone knows what those numbers are I invite you to share them.
Umm.. The upward velocity of the shuttle gives the upward velocity of the foam at the moment of seperation, which plugs into the equation D=1/2*C*p*A*v^2, to give the aerodynamic drag on the foam. Exactly how is that not relevant? Notice that the drag depends on the square of the velocity. Then you plug that into a=D/m+g+S where g is the acceleration of gravity and S is the shuttle's upward acceleration. Rewrite in differential form and integrate to get a damn good model of how fast the foam was traveling at each point along its fall. Maple can do it in a jiffy.
If you'll just give me the correct values of C, A, S, starting altitude, and air temperature, I'll work it out for you right here. I doubt you'll have more success in obtaining those numbers than I have.
Or are you gonna cut us off here before I prove you wrong?
What I can do, however, is look at the video footage. It's pretty easy to calculate how fast the foam was moving if you make a single assumption -- that the acceleration was constant. It's easy to count frames, and NASA knows how long their own shuttle is. I don't understand why people are disputing something that can easily be verified by anyone who looks at the video footage.
If everyone did physics like you did (take guess, scratch head, flip coin, decide whether guess is correct), I think we'd be into the neighboring galaxies by now!
These people are capable of launching a spacecraft from a planet whipping around the sun, through continuously changing gravitational fields, for hundreds of millions of miles, and put it down on a spot the width of your city park. They know physics. To put it bluntly, these people are badasses. The last thing they deserve right now is the intellectual equivalent of a 2 year old arguing over politics with Kofi Annan...
Yeah. You neglected the gigantic fricken' wind blowing past the shuttle. It was flying upward at 1000+ MPH after all. From the piece of foam's perspective, it was being blasted by a 1000 MPH wind. That tends to accelerate stuff.
It's getting really tiring going over this again and again...
Really, I don't see why this is so hard to understand. When you go 60 MPH on a jetski, your eyelids peel back. It isn't because you're accelerating, it's because your going really fast through the air.
The explanation of MHz I've always used is: "That's the number of numbers the computer can add together in a single second." Making some generous assumptions (addition takes one cycle, no cache misses), this is accurate.
I admit it when it happens. I also have the ability to learn pretty much everything relevant about the technology within about 15 minutes (there's this thing called the Internet), so I don't see why it should be embarrassing to admit initial ignorance. I still don't know what the hell SOAP stands for, because I just don't use it. If I had to, I could learn about it in a few minutes. I think most geeks are the same, but many have ego problems that prevent them from admitting ignorance.
At least with my bosses at work, I find that honesty about your knowledge base is always preferrable to spewing BS. You'll get tangled in your own BS pretty quickly.
Ignorance will never be banned, unfortunately.
I don't see why. I think it's genuinely interesting that the Bush administration was able to take over another country based on claimed evidence held behind its back, and get away with it (and now that it's coming out publically that there isn't much evidence for WMD in Iraq, the public seems to really not care), and now Darl seems to be doing the same thing. I wonder if he learned from example?
Why should the possible ideological connection between the two events be considered irrelevant, or "modded down to obliteration?"
So shut up, you little twerp.
Is everyone seriously so impatient to solve the spam problem that they are willing to enact badly worded, overbroad legislation? Give the congress the power to regulate some aspects of the Internet, and that power will quickly expand into other areas. Do we actually want to go down that nightmare path?
Q: "Mr. Senator, how do you plan to pay for the execution of these new spam laws?"
A: "I plan to tax the Internet."
That seems to be saying that it's still okay to use the software even if I don't accept the license. But if I don't accept the license, then there's no disclaimer of liability, right? So in theory could I sue a GPL author for damages as long as I haven't modified and/or distributed the program?
From the article: "The consequential economic damage Intel claims to have suffered, i.e., loss of productivity caused by employees reading and reacting to Hamidi's messages and company efforts to block the messages, is not an injury to the company's interest in its computers -- which worked as intended and were unharmed by the communications -- any more than the personal distress caused by reading an unpleasant letter would be an injury to the recipient's mailbox, or the loss of privacy caused by an intrusive telephone call would be an injury to the recipient's telephone equipment."
Precisely correct.
Intel should have charged him with some form of harrassment. They picked the wrong charge, which was obviously bogus to begin with. For the S.C. to side with Intel on this would have set a terrible and incorrect precedent.
Not that I particularly agree with Hamidi's actions, but this ruling makes sense IMHO.
Adam Osborne's classic blunder
"The final blow occurred in 1983, when Adam Osborne boasted about an upcoming product months before it could be released, killing demand for the company's existing products ... Unsold inventory piled up and OCC declared bankrupcy on September 13 1983. This marketing blunder came to be known as "Osborneing" and the phrase circulated in Silicon Valley for the next decade."
If I knew my gold plated box set was going to be an incomplete box set in two years, I would not buy it.
Bill G.: Hey Steve, looks like we're starting to really get screwed on this Xbox thing. Two million units sold in the last month.
Steve B.: Yeah, don't they know this is costing us money? Idiots!
Bill G.: It's a real shame we can't just stop making them and selling them at a loss.
Steve B.: Yeah, it sure sucks. For some reason I just feel compelled to continue losing money. It's weird.
How else are they supposed to make sure you can hear it from the bathroom?
Traditional X rays work by passing through the body and are literally absorbed by dense material like bone. The resulting image shows regions of high X ray absorption. The reason it works is because the X rays have high enough energy to penetrate the body and come out the other side (except, of course, for where they are absorbed, which is the entire point).
This new technique works by scattering the X rays off the surface of the body. It detects metal objects because they interact strongly with X rays. In a sense it is operating on the reverse principle -- instead of looking for where the X rays are absorbed, it is looking for where they are strongly reflected. It must be that they are using a lower X ray energy, otherwise the X rays would penetrate, not get reflected.
I wouldn't go so far as to say the technology is safe, but the entire point is for the X rays to reflect, i.e., not get absorbed. It's probably safer than a traditional X ray.
Someone attaches an evil .MSW file to an email, and sends it to you. Even though the .MSW itself isn't executable, the application will load it, get exploited, and execute the code -- virus, trojan, backdoor, whatever it is.
Just because it doesn't end with EXE, DLL, PIF, SCR, or some other common executable extension doesn't mean it's harmless. Unless you can trust every app on your system which is registered to some file extension, then those kinds of files can potentially be viruses.
I don't see why you think this is bizarre.
Yes, us poor, stupid individuals don't correctly appreciate his stellar, godlike contributions. We must be reminded of what a great man he is.
If RMS sat down and shut up, I might respect him. No one likes a loud mouthed bad mannered pedant, even if he's "right." Except fellow loud mouthed bad mannered pedants, I assume.
If I could, I would challenge RMS to write a book about the genesis of GNU, without ever using the words "I" or "me." I bet he couldn't do it.
I found a copy of the final draft online: Learning Spam: Simple techniques for freely-available software. The paper covers several machine learning techniques. The particular one I'm talking about here is the information-theoretic clustering and neural network approach.