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Topic: Quantum computer? (Read 12969 times)

sr. member
Activity: 278
Merit: 251
December 14, 2015, 03:23:10 PM
#27
This is not sci-fi anymore. Nasa and Google revealed their first Quantum computer that is 100,000,000 times faster than traditional ones. http://www.pcworld.com/article/3013214/hardware/nasa-google-reveal-quantum-computing-leap.html

Sorry to disabuse you, but the DWAVE technology is not a general purpose quantum computer and can not be used to "break" public key cryptography.  And even if it could be, there wouldn't be any 100M speedup, because that number is from a rigged "benchmark".
hero member
Activity: 644
Merit: 500
December 13, 2015, 07:26:35 AM
#26
Haven't found much on the topic there, so asking away.

Let's say i have a practicable quantum computer or other device capable of rapid factorization of large enough integers.
What are the consequences to a developed bitcoin network?
Any way it could let me cheat in generation?
Any way it would let me cheat in transactions?

With a device of this kind i can get the private key from public key, right?
So after receiving a bitcoin from someone, can i subsequently successfully fake a transfer of all there was on his side?

Actually the usefulness of all these odd features of quantum computing. Well, thanks to those quantum mechanical quirks, a quantum computer could crunch complicated calculations much quicker than the fastest computers today. Because the qubit exists in a superposition of one and zero, rather than one or the other, it can use ones, zeroes, and the superposition of both. By being able to encode multiple possibilities in its fundamental units and It can tackle the problem more efficient than Normal computer.
sr. member
Activity: 475
Merit: 250
December 13, 2015, 06:29:52 AM
#25
Biggest quantum computer yet was able to figure out that 3 and 5 multiplied gave 15.

Actually, it was able to figure out the inverse operation. (15 is produced by which multiplication? Ah, it is 3*5.)  Wink
full member
Activity: 126
Merit: 100
Bitcoin for the Charity :)
December 13, 2015, 01:43:59 AM
#23
i think your Quantum Computer should neaeds 51% of the btcnetwork which is quit impossible..
Simply the google Somputers arent fast enough for thoose tasks.

Anyways why you want to sabotage it. Thats not so good idea i think Wink

regards
BTC LOVER
legendary
Activity: 1218
Merit: 1007
December 13, 2015, 01:11:12 AM
#22
Biggest quantum computer yet was able to figure out that 3 and 5 multiplied gave 15.

I think we will be ok the next 20 years or more Wink


(The 500 qbit computer was a dud, the scientist who discovered the principle behind it, said it did not apply to their solution aka. a big paper weight and no results)
Well I wouldn't necessarily say we'll be fine for the next 20 years, but I can be fairly sure we won't have any issues with Quantum computers for at least another decade.

It's kind of a shame the 500 qbit was a dud, I was hoping that they would be able to usher in a new era of computing soon. But at the same time it does have its own issues, so maybe it is better that it hasn't worked yet.
hero member
Activity: 816
Merit: 1000
December 12, 2015, 07:14:47 AM
#21
Biggest quantum computer yet was able to figure out that 3 and 5 multiplied gave 15.

I think we will be ok the next 20 years or more Wink


(The 500 qbit computer was a dud, the scientist who discovered the principle behind it, said it did not apply to their solution aka. a big paper weight and no results)
hero member
Activity: 714
Merit: 500
December 12, 2015, 03:59:46 AM
#20
Quantum computers can do certain things many, many times faster, but things like hashing wil stay bout the same. Don't worry, unless quantum computers become ridiculously cheap, we all have nothing to worry about. Even then, the community will push out a new type of cryptography that's quantum proof. You have nothing to worry about.

Quantum computers are close to being invented, but not that colose.

This is naive as hell. All you'd need is a single quantum computer to cripple all cryptocurrencies overnight. IOTA (www.iotatoken) is currently the only crypto to take this seriously
sr. member
Activity: 392
Merit: 251
December 12, 2015, 03:47:35 AM
#19
Quantum computers can do certain things many, many times faster, but things like hashing wil stay bout the same. Don't worry, unless quantum computers become ridiculously cheap, we all have nothing to worry about. Even then, the community will push out a new type of cryptography that's quantum proof. You have nothing to worry about.

Quantum computers are close to being invented, but not that colose.
hero member
Activity: 714
Merit: 500
December 11, 2015, 06:55:46 PM
#18
IOTA avoids this by design: http://188.138.57.93/tangle.pdf
legendary
Activity: 840
Merit: 1000
December 11, 2015, 06:49:40 PM
#17
Quantum computers can be very dangerous for many things like banks which can be affected the first, because these computers have large power and can decrypt any encrypted key or crypto algorithm.
hero member
Activity: 980
Merit: 510
December 11, 2015, 04:25:33 PM
#16
Classical computers work linearly, executing a specific set of instructions.  Quantum computing works by setting up a "situation", and then letting it evolve naturally in a quantum physical way, exploring multiple solutions at once.

Think of it like this:  A classical computer acts like a plinko machine.  You put a ball at the top in one of the possible positions, and it clunks down each step until it gets to the bottom.  A quantum computer puts a ball at the top in EVERY position, and lets it fall, until it finds the best one.

The trouble is setting up the situation in a very careful way, such that the interferences between different particles is used to your advantage in the calculation.

Great example for the diff between classical computers and quantum computers.  i think if anyone ever gets a working quantum computer going that could possiblly be capable of this it would probably be a reputable organization who we would hope could be trusted to not screw things up, at least until we get some Quantum Nodes up and running...... Grin  even some Quantum mining rigs..... lol  Wink thats gona be one hell of a difficulty that day.  Shocked
full member
Activity: 131
Merit: 100
December 11, 2015, 04:07:07 PM
#15
I am assuming that what you are referring to would be considered hacking.  From what i understand, there is no way to hack the block-chain that records all of the BTC transactions that make it what it is.  So in order to successfully steal like that, you would need to be able to change all the code to match in place, which is next to impossible with more code being added each second.
sr. member
Activity: 412
Merit: 250
December 11, 2015, 09:46:44 AM
#14
Bitcoin doesn't use encryption. Quantum doesn't doom all kinds of algorithms, our main concern (pending new research) is Shors algorithm.
sr. member
Activity: 412
Merit: 251
December 11, 2015, 04:01:59 AM
#13
Have you head of the Google Dwave computer? It's supposedly 100 million times faster than the average PC.

A quantum computer should be able to calculate some algorithms much faster than others, but things like hashing would stay about the same speed. If there is a need, miners could push out a new type of encryption to prevent quantum computers from dominating the hashrate.
sr. member
Activity: 412
Merit: 250
December 10, 2015, 10:15:05 PM
#12
Quantum computers will pose a threat to ECSDA. Whilst 256-bit ECC is comparable in strength to 4096-bit RSA, to a quantum computer, all it's concerned with is the length of the numbers. A 256-bit integer is far easier to solve for compared to 3072-bit.. A single signature would be enough to compromise a private key, with a strong enough quantum computer. They pose less of an issue to hash functions, so funds received on a bitcoin address are safer (until the first transaction redeeming them reveals it's public key and signature)

While quantum computers of this size aren't practical right now, they soon will be. I read a journal article documenting a quantum computer for factorizing integers using chemical computers. Nuclear magnetic resonance was used to induce quantum states in a molecule containing 5 fluorine atoms (used to store qubits of information). It's a pretty extreme approach (they won't break ECDSA using this setup), but it was also largely successful. (https://cryptome.org/shor-nature.pdf)

We're mainly waiting on something that helps us realize quantum computing to a practical extent, but upgrading bitcoin to use a new signature algorithm can be accomplished by either a soft or hard-fork if preferred. With all systems, they will be upgraded whenever the risk becomes real.

wrt upgrading, we can only make it opt-in, so softfork is probably best. Anyone who has funds protected by ECDSA would move their coins one, to a new scriptPubKey protected by: OP_PQCHECKSIG (post-quantum checksig, whatever we decide to adopt). We would generate a new address type, starting some other prefix besides 1...., or 3....., and then life would carry on!
newbie
Activity: 5
Merit: 0
December 10, 2015, 12:34:59 AM
#11
This is not sci-fi anymore. Nasa and Google revealed their first Quantum computer that is 100,000,000 times faster than traditional ones. http://www.pcworld.com/article/3013214/hardware/nasa-google-reveal-quantum-computing-leap.html
sr. member
Activity: 364
Merit: 250
June 14, 2011, 01:18:21 AM
#10
http://pqcrypto.org/    <- This
qbg
member
Activity: 74
Merit: 10
June 13, 2011, 11:29:39 PM
#9
AFAIK quantum computers are hypothesized to solve the factoring problem, but not the discrete logarithm and SHA256 hash collision problems bitcoin security depends on.
Quantum computers do speed up brute force attacks, but that can be countered by doubling the size of the search space (in bits) if it poses a problem.
newbie
Activity: 42
Merit: 0
June 13, 2011, 05:19:53 PM
#8
any scalable[like SHA family] hash/cipher don't need quantum computing horsepower efficency, just  amount of usual one.
quantum computing is interesting applications are something breaking "otherwise unbreakable" cryptosystems.
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