Yeah there are monsters out there. But it has also been American policy to fight force on force since the 1950's (and maybe even earlier- I'm not entirely sure). Tanks kill tanks, planes kill planes, subs kill subs (again, generally). Therefore it would seem pretty logical to me for monsters to kill monsters.
Well, if that's the official US policy, then thinking that they are out to kill evil guys doesn't make me feel comfortable...
Well, posting a dupe to a post saying that the article is a dupe is just redundant, but doing so while actually knowing that it already has pointed out (as you proof by citing a reply to such a post) is, well, asking for bad karma to the least.
Please! Deep thinking is about abstract thought. There is nothing more abstract than funny little symbols on a page that you have to assemble into meaning.
In Soviet Russia, "In soviet Russia" posts moderate YOU down. And of course, in Korea, only old people write "in Korea, only old people" posts. Imagine a Beowulf cluster of Beowulf clusters!
No, there's no such thing as a GNU/Linux driver. Drivers (except for X11 graphiocs drivers) are a pure kernel thing, and there's no such thing as a GNU/Linux kernel, even not for RMS. So it's a Linux driver, which is used by the Linux kernel of the GNU/Linux operating systems.
Well, while encryption makes things a lot more secure, it actually doesn't completely solve the problem. It just reduces it to the problem of "how do I make sure that the certificate really belongs to the person/organization I believe it belongs to?" The point is, there's always the point where you just have to say "I trust this" or "I trust those". It's relatively easy if you meet someone in person to give the key (but even then only if you already know them, or again have an independend means of identifying, which means to move the trust again to some different point, e.g. if you check the driving license, you have to trust that), it's more difficult if the connection is just through the net.
For example, the browsers come with a preconfigured list of certificates of authorities to trust. Have you ever reviewed those certificates if you trust them? What if someone managed to add a bogus certificate (either directly on your computer using e.g. a virus or worm, or indirectly by cracking a computer which hosts the browser)? Indeed, I must say that I never heared of most of those. I just trust the makers of Mozilla that they added only non-bogus ones.
How does it work? Products of two very big prime numbers, don't ask me more than that 'cos I seriously don't know.
Well, the idea is the following:
The product of two primes has exactly the same information as the two primes themselves (there's exactly one way to factorize a number into primes). However while going from the two primes to the product is trivial (just multiply them), doing the reverse is actually hard.
Now RSA relies on a reversible transformation, where for encryption, you just can use the product directly, but for decryption you need the two primes separately. So if you send someone the product, he can easily encrypt a message with that key, but he cannot decrypt even the message he just encrypted, because to do so he would need to factorize the product, which is hard.
So essentially the public key in principle contains all the information to decrypt (otherwise it could not be used for encryption), but in a form where it is practically useless for decryption (because you just can't get at the necessary information in reasonable time).
Of course this is also just a form of encryption where you have to exchange codes first (both the sender and the receiver must know that language, that is, they must memorize the code. Or of course they could have a grammar book/dictionary (i.e. a written-down version of the code) for that. Which then has the disadvantage that an unauthorized third party may get it.
And it's a code which is hard to change. Say one of the group changes sides, then your whole investment in that code (creating a complete language, and then both sender and receiver having learn it) is immediatly completely worthless.
An n qubit computer is a general 2^n state quantum system. Now emulating an N state quantum system means manipulating vectors of N complex numbers.
Let's try an example: Let's assume that we need only as much precision that we can use a fixed point numer format with a size of one byte. Then a complex number will need 2 bytes, and the vector to just store the quantum state of an n-bit quantum computer will therefore need 2^(n+1) bytes.
According to Wikipedia, there are 6*10^79 atoms in the universe (taking the upper limit of the range given there). That's about 2^265. Now assume we would build a classical computer which stores one (classical) bit in every atom of the whole universe, then our universe-sized classical computer would have 2^262 Bytes of memory. This would be just enough to emulate a quantum computer with only 261 qubits. Now, take a key length of more than 261 bits, and you are completely safe from that universe-sized classical computer.
But not only the memory requirements scale exponentially, also the calculation time does. Given that the simple brute-force algorithm for factorization also has exponential time, I guess that bute-force would probably consistently beat an emulated quantum computer.
However, if someone built a real quantum computer with 261 qubits, he'd just need 261 atoms for storing the state (assuming 1 qubit/atom), and the calculation time would be far from exponential.
If you have the quantum equipment anyway, it's no problem to generate true random numbers. Just produce vertically polarized photons and then measure them in diagonal direction. This guarantees complete independence of the resulting bits from each other (i.e. no correlation), and for perfect vertical and diagonal arrangement also equal probability of 0 and 1. But it's the independence which is really crucial; it's simple to create an unbiased random bit stream from a biased one if the individual bits are independent: Just split the original bit stream into pairs of bits, then throw away all pairs where both bits are the same, and for the remaining pairs always take the first bit. For a stream of independent bits, this guarantees a stream of equally probable independent bits. The bias of the original stream just affects the data rate.
Actually, all of the quantum principles quantum computing is based on are actually experimentally proven. Indeed, quantum computers have been built, except that they are currently restricted to a few qubits. A factorization of 15 with Shor's algorithm has already succeeded.
An unsolved problem, however, is how to build larger quantum computers. Maybe it's impossible in practice to get more than a few individually controllable qubits sufficiently protected from the environment. But that's quite a different statement than the one you made.
They are not trying to get you to program in XML here. I think the point is that they are decoupling the view of how your code looks to you from the logic behind it. This seems like a cool idea.
Actually I prefer if the view of how my code looks to me is coupled strongly to the logig behind it. That is, I want to see the logic, instead of having to figure it out the hard way.
I guess that XML stuff could even get into a security risk, if you could convince the editor to show things differently that the compiler sees that (if the editor supports CSS, then just <statement style="visibility:hidden">(malicious code)</statement> will be enough; but I guess damage could also be done if the XML information says something different than the actual program). That is, you read the code in your editor, it looks safe, you compile and run it, and you lost, because the actual code was not what you've seen.
(Since adding stuff to the end obviously does not help, I'll add nor to the beginning... read below if you want to know what I mean... YES, LAMENESS FILTER, XML IS LAME, BUT HEY, THAT'S NO REASON NOT TO LET ME POST IT! Ok, maybe that helps...... no, not at all, therefore I'll replace some of the spaces below with underscores, please mentally replace those underscores with spaces again.)
(Probably linguists would tell me that my structure is completely off:-))
Oh, and the lameness filter told me: Your comment violated the "postercomment" compression filter. Try less whitespace and/or less repetition. Comment aborted.
Yes, the lameness filter got it exactly right: XML has just too much redundancy!
Indeed, I now got the same message a second time. Therefore I'll just add more junk in order to get this XML stuff through the filter. To avoid repetitions, the person that's me will use different words as much as possible (I am obviously not always able to not use the same term again, of course).
Ok, let's see if now the lameness filter is satisfied.
No, still not. So let me add some more stuff: fhjks hjfkdlgh dfhjklash fjklsd
10 20 42 0 8 1 6 7 5 1278
!"$%&/()=
I'll give you your red.un.dan.cy, you lame la.a.m.e.n.e.s.s fil.ter!
$ $$ $$$ $$$$
Ok, satisfied now?
Ah, still not. Then let's try some more text. To reduce redundancy, I'll now add some German.
Nun denn, dann wollen wir mal sehen, ob der Filter sich auf diese Weise beruhigen läßt. (Und für alle Korinthenkacker: Ja, das ist noch alte Rechtschreibung:-)) Flüssigkeiten sollen ja recht inkompressibel sein, vielleicht kann ja die Aufzählung von solchen hilfreich sein:-) Also: Wasser, Quecksilber, Ammoniak, Öl, Essig, Schwefelsäure
Well, a warning about a new virus would be creative. And the attachment contains the virus signature. Open the attachment to get the virus signature into your computer. Note that without having the signature, your virus scanner likely will not be able to detect the virus.
The ironic thing would be that every single sentence in that mail would be true: Indeed, there's a new virus (right there in the mail, in fact). Of course the attachment contains the virus signature (as part of a complete, working virus). Of course opening the attachment will get the virus signature onto your computer (by getting infected by the virus). And of course the virus scanner will need the virus signature to detect the virus (just that opening the attachment will not help here, of course).
Re:Actually, it's under control
on
MyDoom Strikes Again
·
· Score: 4, Interesting
Unless they use a mailer which doesn't show images... but then, they probably won't open random attachments anyway.
That is, a 2.5 megawatt laser would generate the same energy flux at the satellite as a 80W lightbulb would.
Errr... I should actually have used the review button. This sentence is obviously missing something. It should read: That is, a 2.5 megawatt laser from the surface of earth would generate the same energy flux at the satellite as a 80W lightbulb would from a distance of 1 meter.
Also in the previous sentence, s/80W light bulb/80W light bulb at the distance of 1 meter/.
Ah, and I just noticed that I forgot to close the parentheses...
Sorry, but if you divide a power by the square of a length, then you don't get a power, but power per area (also known as energy flux).
Your calculation would be right if a) the laser had an opening angle of 45 degrees (so radius of covered area equals distance of light), b) the satellite had a cross section of exactly 1 square meter and c) there would be vacuum between you and the satellite.
Now b is not impossible, but a would imply a rather badly focused beam. OTOH c would imply reduced power.
According to this article, a laser gives a spot with a diameter of 7km on the moon (distance 3.6*10^8 m), so at the point of the satellite it would be 7000/3.6e8 * 3.5e7 m = ca. 680 m, which assuming a circular spot gives an area of 3.6e5 m^2.
If there were no atmosphere, for your 250 kW laser pulse, this would amount to an energy flux of about 0.69 W/m^2. Orders of magnitude above your value, but still too low to do any harm (for comparison, the total energy flux of an 80W light bulb [light and heat together, i.e. taking the complete 80W into account] is about 6.4 W/m^2. That is, a 2.5 megawatt laser would generate the same energy flux at the satellite as a 80W lightbulb would.
Now, what will the satellite have to cope with anyway? Well, obviously the sun. Now, the energy flux of the sun above atmosphere is 1370W/m^2. That is, even the 2.5 megawatt laser would just add 0.5% to the energy flux the sun throws at the satellite anyway.
That's of course without taking into account the atmosphere.
Slashdot Mirror
Well, if that's the official US policy, then thinking that they are out to kill evil guys doesn't make me feel comfortable
Well, posting a dupe to a post saying that the article is a dupe is just redundant, but doing so while actually knowing that it already has pointed out (as you proof by citing a reply to such a post) is, well, asking for bad karma to the least.
AdAGFGgfdgdfKfHKJGHfffGK
Well, accompany the game with a book, and make it clear that by reading the book you increase the chances of winning the game ...
Nethack?
In Soviet Russia, "In soviet Russia" posts moderate YOU down.
And of course, in Korea, only old people write "in Korea, only old people" posts.
Imagine a Beowulf cluster of Beowulf clusters!
No, there's no such thing as a GNU/Linux driver. Drivers (except for X11 graphiocs drivers) are a pure kernel thing, and there's no such thing as a GNU/Linux kernel, even not for RMS. So it's a Linux driver, which is used by the Linux kernel of the GNU/Linux operating systems.
If you see him requesing the MD5 hash, just send the one of your modified file instead.
Well, while encryption makes things a lot more secure, it actually doesn't completely solve the problem. It just reduces it to the problem of "how do I make sure that the certificate really belongs to the person/organization I believe it belongs to?"
The point is, there's always the point where you just have to say "I trust this" or "I trust those". It's relatively easy if you meet someone in person to give the key (but even then only if you already know them, or again have an independend means of identifying, which means to move the trust again to some different point, e.g. if you check the driving license, you have to trust that), it's more difficult if the connection is just through the net.
For example, the browsers come with a preconfigured list of certificates of authorities to trust. Have you ever reviewed those certificates if you trust them? What if someone managed to add a bogus certificate (either directly on your computer using e.g. a virus or worm, or indirectly by cracking a computer which hosts the browser)? Indeed, I must say that I never heared of most of those. I just trust the makers of Mozilla that they added only non-bogus ones.
Well, the idea is the following:
The product of two primes has exactly the same information as the two primes themselves (there's exactly one way to factorize a number into primes). However while going from the two primes to the product is trivial (just multiply them), doing the reverse is actually hard.
Now RSA relies on a reversible transformation, where for encryption, you just can use the product directly, but for decryption you need the two primes separately. So if you send someone the product, he can easily encrypt a message with that key, but he cannot decrypt even the message he just encrypted, because to do so he would need to factorize the product, which is hard.
So essentially the public key in principle contains all the information to decrypt (otherwise it could not be used for encryption), but in a form where it is practically useless for decryption (because you just can't get at the necessary information in reasonable time).
Which of course only works if there's a running, trusted computer to connect to on the net.
Of course this is also just a form of encryption where you have to exchange codes first (both the sender and the receiver must know that language, that is, they must memorize the code. Or of course they could have a grammar book/dictionary (i.e. a written-down version of the code) for that. Which then has the disadvantage that an unauthorized third party may get it.
And it's a code which is hard to change. Say one of the group changes sides, then your whole investment in that code (creating a complete language, and then both sender and receiver having learn it) is immediatly completely worthless.
An n qubit computer is a general 2^n state quantum system. Now emulating an N state quantum system means manipulating vectors of N complex numbers.
Let's try an example: Let's assume that we need only as much precision that we can use a fixed point numer format with a size of one byte. Then a complex number will need 2 bytes, and the vector to just store the quantum state of an n-bit quantum computer will therefore need 2^(n+1) bytes.
According to Wikipedia, there are 6*10^79 atoms in the universe (taking the upper limit of the range given there). That's about 2^265. Now assume we would build a classical computer which stores one (classical) bit in every atom of the whole universe, then our universe-sized classical computer would have 2^262 Bytes of memory. This would be just enough to emulate a quantum computer with only 261 qubits. Now, take a key length of more than 261 bits, and you are completely safe from that universe-sized classical computer.
But not only the memory requirements scale exponentially, also the calculation time does. Given that the simple brute-force algorithm for factorization also has exponential time, I guess that bute-force would probably consistently beat an emulated quantum computer.
However, if someone built a real quantum computer with 261 qubits, he'd just need 261 atoms for storing the state (assuming 1 qubit/atom), and the calculation time would be far from exponential.
If you have the quantum equipment anyway, it's no problem to generate true random numbers. Just produce vertically polarized photons and then measure them in diagonal direction. This guarantees complete independence of the resulting bits from each other (i.e. no correlation), and for perfect vertical and diagonal arrangement also equal probability of 0 and 1. But it's the independence which is really crucial; it's simple to create an unbiased random bit stream from a biased one if the individual bits are independent: Just split the original bit stream into pairs of bits, then throw away all pairs where both bits are the same, and for the remaining pairs always take the first bit. For a stream of independent bits, this guarantees a stream of equally probable independent bits. The bias of the original stream just affects the data rate.
Actually, all of the quantum principles quantum computing is based on are actually experimentally proven. Indeed, quantum computers have been built, except that they are currently restricted to a few qubits. A factorization of 15 with Shor's algorithm has already succeeded.
An unsolved problem, however, is how to build larger quantum computers. Maybe it's impossible in practice to get more than a few individually controllable qubits sufficiently protected from the environment. But that's quite a different statement than the one you made.
Well, probably you just tried to troll anyway.
Does HTML/XHTML allow "rel" attributes on links? And if so, is "nofollow" an allowed value for that tag?
Actually I prefer if the view of how my code looks to me is coupled strongly to the logig behind it. That is, I want to see the logic, instead of having to figure it out the hard way.
I guess that XML stuff could even get into a security risk, if you could convince the editor to show things differently that the compiler sees that (if the editor supports CSS, then just <statement style="visibility:hidden">(malicious code)</statement> will be enough; but I guess damage could also be done if the XML information says something different than the actual program). That is, you read the code in your editor, it looks safe, you compile and run it, and you lost, because the actual code was not what you've seen.
YES, LAMENESS FILTER, XML IS LAME, BUT HEY, THAT'S NO REASON NOT TO LET ME POST IT!
Ok, maybe that helps
(Probably linguists would tell me that my structure is completely off :-))
:-)) Flüssigkeiten sollen ja recht inkompressibel sein, vielleicht kann ja die Aufzählung von solchen hilfreich sein :-)
Oh, and the lameness filter told me:
Your comment violated the "postercomment" compression filter. Try less whitespace and/or less repetition. Comment aborted.
Yes, the lameness filter got it exactly right: XML has just too much redundancy!
Indeed, I now got the same message a second time. Therefore I'll just add more junk in order to get this XML stuff through the filter. To avoid repetitions, the person that's me will use different words as much as possible (I am obviously not always able to not use the same term again, of course).
Ok, let's see if now the lameness filter is satisfied.
No, still not. So let me add some more stuff: fhjks hjfkdlgh dfhjklash fjklsd
10 20 42 0 8 1 6 7 5 1278
!"$%&/()=
I'll give you your red.un.dan.cy, you lame la.a.m.e.n.e.s.s fil.ter!
$ $$ $$$ $$$$
Ok, satisfied now?
Ah, still not. Then let's try some more text. To reduce redundancy, I'll now add some German.
Nun denn, dann wollen wir mal sehen, ob der Filter sich auf diese Weise beruhigen läßt. (Und für alle Korinthenkacker: Ja, das ist noch alte Rechtschreibung
Also: Wasser, Quecksilber, Ammoniak, Öl, Essig, Schwefelsäure
You misunderstood. They are developing a router which drops everything but whitespace characters.
So you mean the only reason why we didn't yet have contact to extraterrestials is the missing space routers?
Well, a warning about a new virus would be creative. And the attachment contains the virus signature. Open the attachment to get the virus signature into your computer. Note that without having the signature, your virus scanner likely will not be able to detect the virus.
The ironic thing would be that every single sentence in that mail would be true: Indeed, there's a new virus (right there in the mail, in fact). Of course the attachment contains the virus signature (as part of a complete, working virus). Of course opening the attachment will get the virus signature onto your computer (by getting infected by the virus). And of course the virus scanner will need the virus signature to detect the virus (just that opening the attachment will not help here, of course).
Unless they use a mailer which doesn't show images ... but then, they probably won't open random attachments anyway.
From Wikipedia: Intelsat maintains it headquarters in Bermuda
Bermuda? And then anyone wonders that their satellites disappear?
Errr
This sentence is obviously missing something. It should read:
That is, a 2.5 megawatt laser from the surface of earth would generate the same energy flux at the satellite as a 80W lightbulb would from a distance of 1 meter.
Also in the previous sentence, s/80W light bulb/80W light bulb at the distance of 1 meter/.
Ah, and I just noticed that I forgot to close the parentheses
Sorry, but if you divide a power by the square of a length, then you don't get a power, but power per area (also known as energy flux).
Your calculation would be right if
a) the laser had an opening angle of 45 degrees (so radius of covered area equals distance of light),
b) the satellite had a cross section of exactly 1 square meter and
c) there would be vacuum between you and the satellite.
Now b is not impossible, but a would imply a rather badly focused beam. OTOH c would imply reduced power.
According to this article, a laser gives a spot with a diameter of 7km on the moon (distance 3.6*10^8 m), so at the point of the satellite it would be 7000/3.6e8 * 3.5e7 m = ca. 680 m, which assuming a circular spot gives an area of 3.6e5 m^2.
If there were no atmosphere, for your 250 kW laser pulse, this would amount to an energy flux of about 0.69 W/m^2. Orders of magnitude above your value, but still too low to do any harm (for comparison, the total energy flux of an 80W light bulb [light and heat together, i.e. taking the complete 80W into account] is about 6.4 W/m^2. That is, a 2.5 megawatt laser would generate the same energy flux at the satellite as a 80W lightbulb would.
Now, what will the satellite have to cope with anyway? Well, obviously the sun. Now, the energy flux of the sun above atmosphere is 1370W/m^2. That is, even the 2.5 megawatt laser would just add 0.5% to the energy flux the sun throws at the satellite anyway.
That's of course without taking into account the atmosphere.