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Author Topic: Quantum computer? So what! No worries...(?)  (Read 4871 times)
jonald_fyookball
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March 30, 2014, 01:32:13 AM
 #21

Funny reading this thread.  Known quantum computers can barely do a basic problem a 1950 calculator could do but everyone still speculates.

15 = 3 x 5 is the most they can calculate at this time in the game.


But if they ever do figure out quantum computing, bitcoin could be hacked in under an hour.  It won't matter that the numbers are so large that typical computers would take longer than the age of the universe. Quantum computing essentially tries every possible solution at once.


http://www.popsci.com/science/article/2012-08/quantum-processor-calculates-15-3x5-about-half-time



Factoring numbers is one thing.  Solving a cryptographic hash is another.  What's the connection?

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March 30, 2014, 01:39:50 AM
 #22

Funny reading this thread.  Known quantum computers can barely do a basic problem a 1950 calculator could do but everyone still speculates.

15 = 3 x 5 is the most they can calculate at this time in the game.


But if they ever do figure out quantum computing, bitcoin could be hacked in under an hour.  It won't matter that the numbers are so large that typical computers would take longer than the age of the universe. Quantum computing essentially tries every possible solution at once.


http://www.popsci.com/science/article/2012-08/quantum-processor-calculates-15-3x5-about-half-time



Factoring numbers is one thing.  Solving a cryptographic hash is another.  What's the connection?


Point is, quantum computing is so early in the stage that they can't even do basic math.  When the figure out how to harness quantum's potential then nothing will be safe.  Factoring or cryptography or any other math mathematical equation will be done in minutes.  Quantum physics suggest all solutions are attempted at once whereas a typical computer attempts to process a problem one step at a time until solved.   What was your point? (I think I missed it)
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March 30, 2014, 01:42:03 AM
 #23

Funny reading this thread.  Known quantum computers can barely do a basic problem a 1950 calculator could do but everyone still speculates.

15 = 3 x 5 is the most they can calculate at this time in the game.


But if they ever do figure out quantum computing, bitcoin could be hacked in under an hour.  It won't matter that the numbers are so large that typical computers would take longer than the age of the universe. Quantum computing essentially tries every possible solution at once.


http://www.popsci.com/science/article/2012-08/quantum-processor-calculates-15-3x5-about-half-time



Factoring numbers is one thing.  Solving a cryptographic hash is another.  What's the connection?


Point is, quantum computing is so early in the stage that they can't even do basic math.  When the figure out how to harness quantum's potential then nothing will be safe.  Factoring or cryptography or any other math mathematical equation will be done in minutes.  Quantum physics suggest all solutions are attempted at once whereas a typical computer attempts to process a problem one step at a time until solved.   

But there is no equation to undo a hash function.

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March 30, 2014, 01:56:11 AM
 #24

Funny reading this thread.  Known quantum computers can barely do a basic problem a 1950 calculator could do but everyone still speculates.

15 = 3 x 5 is the most they can calculate at this time in the game.


But if they ever do figure out quantum computing, bitcoin could be hacked in under an hour.  It won't matter that the numbers are so large that typical computers would take longer than the age of the universe. Quantum computing essentially tries every possible solution at once.


http://www.popsci.com/science/article/2012-08/quantum-processor-calculates-15-3x5-about-half-time



Factoring numbers is one thing.  Solving a cryptographic hash is another.  What's the connection?


Point is, quantum computing is so early in the stage that they can't even do basic math.  When the figure out how to harness quantum's potential then nothing will be safe.  Factoring or cryptography or any other math mathematical equation will be done in minutes.  Quantum physics suggest all solutions are attempted at once whereas a typical computer attempts to process a problem one step at a time until solved.   

But there is no equation to undo a hash function.

Ok, I see what your getting at.  But there still is a solution (answer) to the problem.  And a theoretical fully working quantum computer could still try every possible solution at once.
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March 30, 2014, 03:00:59 AM
 #25

When the figure out how to harness quantum's potential then nothing will be safe.  Factoring or cryptography or any other math mathematical equation will be done in minutes.  Quantum physics suggest all solutions are attempted at once whereas a typical computer attempts to process a problem one step at a time until solved.
Quantum physics suggests no such thing. Where'd you get that idea? Quantum computers aren't magical. They are limited by the same laws of physics as any other computer. It is completely impossible for a quantum computer to brute force a private key. The two quantum algorithms of interest to cryptanalysists (Shor's algorithm and Grover's algorithm) are interesting because they are not a brute force approach, instead they are a mathematical shortcut, in the same way that, say, a preimage attack is a shortcut.

Shor's algorithm is only applicable to factorisation, or problems that can be generalised to factorisation. This includes most commonly used public-key cryptosystems, including ECC. However, there are public-key cryptosystems that cannot be broken this way, and Bitcoin could switch to such a system if necessary. Note also that no symmetic cypher or hash function is broken by Shor's algorithm.

Grover's algorithm is more general, but only speeds up the search by the square root of the keyspace, or to put it another way, the effective key size is halved. So a 256 bit key can be found in 2^128 steps instead of 2^256. However, 2^128 is still far too large to brute force, so 256 bit keys are still safe.

There's no such thing as magic.

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March 30, 2014, 03:04:49 AM
 #26

Quantum on the picture does not seem to look like dumplings.

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March 30, 2014, 03:06:29 AM
 #27

When the figure out how to harness quantum's potential then nothing will be safe.  Factoring or cryptography or any other math mathematical equation will be done in minutes.  Quantum physics suggest all solutions are attempted at once whereas a typical computer attempts to process a problem one step at a time until solved.
Quantum physics suggests no such thing. Where'd you get that idea? Quantum computers aren't magical. They are limited by the same laws of physics as any other computer. It is completely impossible for a quantum computer to brute force a private key. The two quantum algorithms of interest to cryptanalysists (Shor's algorithm and Grover's algorithm) are interesting because they are not a brute force approach, instead they are a mathematical shortcut, in the same way that, say, a preimage attack is a shortcut.

Shor's algorithm is only applicable to factorisation, or problems that can be generalised to factorisation. This includes most commonly used public-key cryptosystems, including ECC. However, there are public-key cryptosystems that cannot be broken this way, and Bitcoin could switch to such a system if necessary. Note also that no symmetic cipher or hash function is broken by Shor's algorithm.

Grover's algorithm is more general, but only speeds up the search by the square root of the keyspace, or to put it another way, the effective key size is halved. So a 256 bit key can be found in 2^128 steps instead of 2^256. However, 2^128 is still far too large to brute force, so 256 bit keys are still safe.

There's no such thing as magic.

Thanks fox !  Can you please explain further how factorization applies to public key cryptography ?

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March 30, 2014, 03:58:39 AM
 #28

When the figure out how to harness quantum's potential then nothing will be safe.  Factoring or cryptography or any other math mathematical equation will be done in minutes.  Quantum physics suggest all solutions are attempted at once whereas a typical computer attempts to process a problem one step at a time until solved.
Quantum physics suggests no such thing. Where'd you get that idea? Quantum computers aren't magical. They are limited by the same laws of physics as any other computer. It is completely impossible for a quantum computer to brute force a private key. The two quantum algorithms of interest to cryptanalysists (Shor's algorithm and Grover's algorithm) are interesting because they are not a brute force approach, instead they are a mathematical shortcut, in the same way that, say, a preimage attack is a shortcut.

Shor's algorithm is only applicable to factorisation, or problems that can be generalised to factorisation. This includes most commonly used public-key cryptosystems, including ECC. However, there are public-key cryptosystems that cannot be broken this way, and Bitcoin could switch to such a system if necessary. Note also that no symmetic cypher or hash function is broken by Shor's algorithm.

Grover's algorithm is more general, but only speeds up the search by the square root of the keyspace, or to put it another way, the effective key size is halved. So a 256 bit key can be found in 2^128 steps instead of 2^256. However, 2^128 is still far too large to brute force, so 256 bit keys are still safe.

There's no such thing as magic.
Quote
Quantum physics suggests no such thing. Where'd you get that idea? Quantum computers aren't magical. They are limited by the same laws of physics as any other computer.

You might have misunderstood my comments in regards to quantum physics.  But let me just say a quantum computer could follow "Quantum Physics" and not the "same laws of physics as any other computer" like you mentioned.  (I would love to see a regular computer use quantum entanglement for data transfers....lol) People who know quantum physics will understand what I just said.

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March 30, 2014, 04:08:16 AM
 #29

You obviously don't know what the hell you are talking about in regards to quantum physics.  And I don't have the time to educate you on a bitcoin forum.  But let me just say a quantum computer could follow "Quantum Physics" and not the "same laws of physics as any other computer" like you mentioned.  (I would love to see a regular computer use quantum entanglement for data transfers....lol) People who know quantum physics will understand what I just said.
People who know quantum physics are laughing at you right now.

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March 30, 2014, 04:26:08 AM
 #30

With all due respect singlebyte, foxpup sounds like he knows what he is talking about, and you definitely do not, at least on this topic.  Please stop the foolish arguments and let the people who want to learn (myself) do so from people with knowledge.

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March 30, 2014, 04:49:03 AM
 #31

Thanks fox !  Can you please explain further how factorization applies to public key cryptography ?
In public-key cryptography, you have a public key and a private key, which are mathematically related. Specifically, they are related (in the simplest case) by the product of two prime numbers. This product is part of the public key, and the private key is calculated from the primes. Since the product of the primes is public, if you can factorise this product, you can calculate the private key. The security of public-key algorithms using this or similar methods is predicated on the assumption that doing so is Really Hard. Again, there are public-key algorithms that don't involve such methods, and these algorithms are not broken by faster methods of factorisation.

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March 30, 2014, 04:55:10 AM
 #32

Thanks fox !  Can you please explain further how factorization applies to public key cryptography ?
In public-key cryptography, you have a public key and a private key, which are mathematically related. Specifically, they are related (in the simplest case) by the product of two prime numbers. This product is part of the public key, and the private key is calculated from the primes. Since the product of the primes is public, if you can factorise this product, you can calculate the private key. The security of public-key algorithms using this or similar methods is predicated on the assumption that doing so is Really Hard. Again, there are public-key algorithms that don't involve such methods, and these algorithms are not broken by faster methods of factorisation.

Cool.  What about Sha256 specifically?  I read about it and it's a long iterative process.  I thought the priv key was the hash of pub address or something... Thx in advance

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March 30, 2014, 04:58:35 AM
 #33

With all due respect singlebyte, foxpup sounds like he knows what he is talking about, and you definitely do not, at least on this topic.  Please stop the foolish arguments and let the people who want to learn (myself) do so from people with knowledge.

All right, I'll jump back in.  What part do you believe that I do not understand about quantum physics?  I may not be versed in cryptography as much but I guarantee I know quantum mechanics fairly good.  I doubt either of you know what quantum entanglement is or why Einstein called it spooky action at a distance?  Do either of you know how quantum entanglement could be used in a quantum computer?  Today's quantum computers are only using 3 states of a qubit.  What if they unlock all states of the qubit spin?  Did either of you even know current quantum computers can only solve the most basic math?  

---removed hostile tone remarks----

As you are right jonald this thread has got of course and we should stop hijacking it.  I will let it die.  On one last note, it does sound like foxpup does know cryptography fairly well.


-Edit-
Replying to jonald thread below (Didn't want to hijack thread with additional posts)

Jonald, you make good points and thanks for replying.  Regarding how the basics of quantum computer work you may find this article below useful.  It is easy to understand and follow.  It tells how "parallelism allows a quantum computer to work on a million computations at once" (depending on how many qubits used) And it discusses Shor's algorithm.   I think you may enjoy it:

http://computer.howstuffworks.com/quantum-computer1.htm


Foxpup...Apology for getting in argument over something so stupid.  I have edited my earlier thread to tone down the discussion.
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March 30, 2014, 05:13:57 AM
 #34

With all due respect singlebyte, foxpup sounds like he knows what he is talking about, and you definitely do not, at least on this topic.  Please stop the foolish arguments and let the people who want to learn (myself) do so from people with knowledge.

All right, I'll jump back in.  What part do you believe that I do not understand about quantum physics?  I may not be versed in cryptography as much but I guarantee I know quantum mechanics fairly good.  I doubt either of you know what quantum entanglement is or why Einstein called it spooky action at a distance?  Do either of you know how quantum entanglement could be used in a quantum computer?  Today's quantum computers are only using 3 states of a qubit.  What if they unlock all states of the qubit spin?  Did either of you even know current quantum computers can only solve the most basic math? 

I find it laughable that foxpup thinks a quantum computer will have to play by the same physic rules as a normal computer.  And "it's not magic" comment is equallably a joke.  Quantum theory will blow your mind when you start discovering that seemingly particles change to waves and back again when you observe them. 

As you are right jonald this thread has got of course and we should stop hijacking it.  I will let it die.  On one last note, it does sound like foxpup does know cryptography fairly well.




Singlebyte,

I admit I am not a expert on either topic.  I always try to remain humble
and aware that "I don't know what I don't know."   

I'm sure you have some good information. 

The reason I said you didn't sound like you know what you are talking about
was primarily the "it tries all solutions simultaneously" notion, which
As fox pup alluded to, sounds like hocus pocus.  The other reason
is that by it's very nature, (to my knowledge) quantum mechanics
operates on microscopic scales.  The notion of a computer
making use of quantum mechanics on a grand scale seems
paradoxical in theory (to me) and in practice we haven't seen progress.



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March 30, 2014, 05:32:39 AM
 #35

All right, I'll jump back in.  What part do you believe that I do not understand about quantum physics?
The entirety of it.

I may not be versed in cryptography
Don't you think that any discussion on the subject would be more meaningful if you knew even the slightest thing about it?

I guarantee I know quantum mechanics fairly good.
I guarantee you don't.

I doubt either of you know what quantum entanglement is or why Einstein called it spooky action at a distance?
Entanglement is where two particles are known to have complimentary states, to preserve the symmetry, thus if a particle is observed to be in one state, the state of the other particle is immediately known, even if it cannot be observed, and there is no way for information about the first particle's state to be transmitted to the second particle. Spooky. This behaviour exists in classical physics, too: take a coin, slice it in half so that you have a head-half and a tail-half, put the coins in separate envelopes, and mail them to two different people. Whoever opens his envelope and discovers that he has the head-half instantly knows that the other person must have got the tail-half, even if the other person hasn't opened his envelope yet, and even if the envelopes were mailed in opposite directions at the speed of light, so there's no possible way that either party could know about the other envelope. But that's not as spooky.

Do either of you know how quantum entanglement could be used in a quantum computer?  Today's quantum computers are only using 3 states of a qubit.  What if they unlock all states of the qubit spin?
Your ignorance manifests yet again. There are only 2 states of a qubit. It can exist in a superposition of both states, but when it is observed, it will be found to be in one state or the other, with no way to predict which (though the probability can be known).

Did either of you even know current quantum computers can only solve the most basic math?
Everyone knows that.

I find it laughable that foxpup thinks a quantum computer will have to play by the same physic rules as a normal computer.  And "it's not magic" comment is equallably a joke.  Quantum theory will blow your mind when you start discovering that seemingly particles change to waves and back again when you observe them. 
You learned about quantum physics from watching Star Trek, didn't you?

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March 30, 2014, 06:23:06 AM
 #36

Damn foxpup....I just appologized and edited my previous threads to tone them down....then I saw your latest post.  Guess I need to reply....


Quote
Don't you think that any discussion on the subject would be more meaningful if you knew even the slightest thing about it?

The thread title is Quantum Computers isn't it?  Didn't notice cryptography in the title.


Quote
Entanglement is where two particles are known to have complimentary states, to preserve the symmetry, thus if a particle is observed to be in one state, the state of the other particle is immediately known, even if it cannot be observed, and there is no way for information about the first particle's state to be transmitted to the second particle. Spooky. This behaviour exists in classical physics, too: take a coin, slice it in half so that you have a head-half and a tail-half, put the coins in separate envelopes, and mail them to two different people. Whoever opens his envelope and discovers that he has the head-half instantly knows that the other person must have got the tail-half, even if the other person hasn't opened his envelope yet, and even if the envelopes were mailed in opposite directions at the speed of light, so there's no possible way that either party could know about the other envelope. But that's not as spooky.

Appears like you either copied and paste this from another site or you quickly read up on it.  But basically this is correct.  Your envelope example however is wrong.  Einstein used a similar analogy (Left and Right gloves) but was found to be wrong in later experiments with his example.  Here is a good 15 minute video explaining entanglement and proving Einstein was wrong with glove theory.
http://youtu.be/ZNedBrG9E90

If you did type this on your own then I would say you have a fairly decent knowledge.


Quote
There are only 2 states of a qubit. It can exist in a superposition of both states, but when it is observed, it will be found to be in one state or the other, with no way to predict which (though the probability can be known).

Wrong...qubits can be in any unlimited number of states (they spin).  Your back to talking quantum entanglement or the "Observed state."  (Left or right).  Magnets have two states (N & S)


Any way this is getting old....

Night!

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March 30, 2014, 11:32:19 AM
 #37

Surely a computer of that size and magnitude must be able to take over 51% of the total hash rate?...

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March 30, 2014, 12:12:25 PM
 #38

Surely a computer of that size and magnitude must be able to take over 51% of the total hash rate?...
Then there wouldn't be only one right? And no, at the most 12%
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March 30, 2014, 12:31:40 PM
 #39

Surely a computer of that size and magnitude must be able to take over 51% of the total hash rate?...
Then there wouldn't be only one right? And no, at the most 12%

You guys have me confused now.

I though quantums are useless when it comes to sha-256...

Or did I not get it right?



███████████████████████████████████████████████████
██████████████████████████████████████████████████

     ▄▄▄▄▄▄▄▄▄            █     ███           ███   ▄▄▄          █          ▄▄▄▄▄▄▄▄▄▄▄▄
   ▄███████████▄         ███     ███         ███    ███         ███         ██████████████▄
 ▄███▀       ▀█▀        █████     ███       ███     ███        █████        ███        ▀▀███
▄██▀                   ███ ███     ███     ███      ███       ███ ███       ███          ███
███                   ███   ███     ███   ███       ███      ███   ███      ███        ▄▄███
███                  ███     ███     ███ ███        ███     ███     ███     ██████████████▀
▀██▄                ███       ███     █████         ███    ███       ███    ███▀▀▀▀▀███▄
 ▀███▄       ▄█▄   ███         ███     ███          ███   ███         ███   ███      ▀███▄
   ▀███████████▀  ███           ███     █           ███  ███           ███  ███        ▀███▄
     ▀▀▀▀▀▀▀▀▀   ███
                ███
▌  .
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April 01, 2014, 02:53:23 PM
 #40

Surely a computer of that size and magnitude must be able to take over 51% of the total hash rate?...
Then there wouldn't be only one right? And no, at the most 12%

You guys have me confused now.

I though quantums are useless when it comes to sha-256...

Or did I not get it right?



Well it's like mining with a cpu. But I do believe even if that's the case if the computer is powerful enough maybe it'll work  Tongue
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