Quantum Computer.

[Truecoin]

If you are interested in programming you can already start to develop your own quantum computer software (and test it with conventional computer): http://tph.tuwien.ac.at/~oemer/qcl.html

[BTCtalkScammerDetective]

I want a quantum computer now.

Time to become a multi-bilionaire.

To be able to get one you would need to be a multi millionaire.

[RedDiamond]

I will start worrying (and educating myself) about quantum computers when they start factoring very large numbers. Until then...same category as interdimensional aliens using advanced technology to hijack the blockchain.

If you really want to educate yourself here is a qcl implementation for Shor's algorithm for quantum factorization (http://tph.tuwien.ac.at/~oemer/doc/quprog/node18.html):

Code:

procedure shor(int number) {
  int width=ceil(log(number,2));   // size of number in bits
  qureg reg1[2*width];             // first register
  qureg reg2[width];               // second register
  int qmax=2^width;
  int factor;                      // found factor
  int m; real c;                   // measured value
  int x;                           // base of exponentiation
  int p; int q;                    // rational approximation p/q
  int a; int b;                    // possible factors of number
  int e;                           // e=x^(q/2) mod number

  if number mod 2 == 0 { exit "number must be odd"; }
  if testprime(number) { exit "prime number"; }
  if testprimepower(number) { exit "prime power"; };

  {
    {                              // generate random base
      x=floor(random()*(number-3))+2;
    } until gcd(x,number)==1;
    print "chosen random x =",x;
    Mix(reg1);                     // Hadamard transform
    expn(x,number,reg1,reg2);      // modular exponentiation
    measure reg2;                  // measure 2nd register
    dft(reg1);                     // Fourier transform
    measure reg1,m;                // measure 1st register
    reset;                         // clear local registers

    if m==0 {                      // failed if measured 0
      print "measured zero in 1st register. trying again ...";
    } else {
      c=m*0.5^(2*width);           // fixed point form of m
      q=denominator(c,qmax);       // find rational approximation
      p=floor(q*m*c+0.5);
      print "measured",m,", approximation for",c,"is",p,"/",q;
      if q mod 2==1 and 2*q<qmax { // odd q ? try expanding p/q
        print "odd denominator, expanding by 2";
        p=2*p; q=2*q;
      }
      if q mod 2==1 {              // failed if odd q
        print "odd period. trying again ...";
      } else {
        print "possible period is",q;
        e=powmod(x,q/2,number);    // calculate candidates for
        a=(e+1) mod number;        // possible common factors
        b=(e+number-1) mod number; // with number
        print x,"^",q/2,"+ 1 mod",number,"=",a,",",
              x,"^",q/2,"- 1 mod",number,"=",b;
        factor=max(gcd(number,a),gcd(number,b));
      }
    }
  } until factor>1 and factor<number;   
  print number,"=",factor,"*",number/factor;
}

So not so alien  

[Ayers]

I want a quantum computer now.

Time to become a multi-bilionaire.

you can't brute force the private key even with those beast, so relax

[jonald_fyookball]

I want a quantum computer now.

Time to become a multi-bilionaire.

you can't brute force the private key even with those beast, so relax

All the kings horses and all the king's men,
couldn't put Satoshi's private keys together again. 

[Bitcoin Magazine]

seeing "demoniator" made me think of this Home IMprovement sketch

https://www.youtube.com/watch?v=lMLZexFH50c

[Este Nuno]

If quantum computers really going to exist, we will need to update our crypto protocols to stronger ones(SHA-1024)?

But the same crypto technology still can be used, so we will only need some adaptation after the panic wave

If they really can break one-way mathematical functions, just updating to a more complex one doesn't work... It's a question of what exactly will be possible with quantum computers.

sigh...already been discussed to death in other threads.

there is no known or even theorized quantum algo or speedup for breaking one way functions.
only ECDSA.

Yeah: no _known_! Like I said, we'll probably be safe off, but can't be sure since something just _might_ come around the corner and prove our current systems to be flawed. It wouldn't be the first time that happened with some technology!

It is definitely something to keep in mind. A lot of people seem to dismiss it outright but really it's kind of a big deal.

[RedDiamond]

There is a good article in Bitcoin Magazine "Bitcoin Is Not Quantum-Safe, And How We Can Fix It When Needed" by Vitalik Buterin: http://bitcoinmagazine.com/6021/bitcoin-is-not-quantum-safe-and-how-we-can-fix/

"In the past year or so, it has come to be a known fact in Bitcoin technical circles that Bitcoin, in its current form, is partially quantum-safe"

[Ayers]

There is a good article in Bitcoin Magazine "Bitcoin Is Not Quantum-Safe, And How We Can Fix It When Needed" by Vitalik Buterin: http://bitcoinmagazine.com/6021/bitcoin-is-not-quantum-safe-and-how-we-can-fix/

"In the past year or so, it has come to be a known fact in Bitcoin technical circles that Bitcoin, in its current form, is partially quantum-safe"

only the public key is not safe, the private is safe, the public key is not safe if you send money, otherwise even that is safe

[Sitarow]

Guys i wanted to discuss about quantum computers, How will they affect BTC

1st thing is that these computers will be 1000s of times faster than the current super computer so my question is what will happen to the difficulty if it rises like a rocket then the price of BTC will also rise like a rocket?

2nd thing is hacking, When these computers get to the consumer market won't hacking become a problem?

Edit: One more question will this also mean the 21 million bitcoins will be made faster?

For now i have got these points i will edit as the post progresses.

Maybe you will enjoy what will happen to a very old Bitcoin clone:
iXcoin IXC   : a 3 years time tested coin, like Bitcoin but bravely ending mining on Oct 2014: it will be interesting to see what happens.

If no one uses it for trade and if it's not a trusted network then it is nothing more then a legacy protocol.

Bitcoin is different as it takes into account  sinergy of variables that keeps it improving with use

[zedicus]

what are you saying is BS?

Everything that he said is 100% bullshit. I did the research and he is pulling stuff out of his ass.

What did you find?  According to wikipedia, 143 is the largest number ever factored
by a quantum machine.  To me, that counts pretty much as "zero results".

Wikipedia is not a reliable source as anyone can change a wikipedia article. I would say that the largest number ever factored by a quantum computer is much larger then 143, likely millions of times larger. Most personal computers/laptop could likely factor much larger numbers.

[jonald_fyookball]

what are you saying is BS?

Everything that he said is 100% bullshit. I did the research and he is pulling stuff out of his ass.

What did you find?  According to wikipedia, 143 is the largest number ever factored
by a quantum machine.  To me, that counts pretty much as "zero results".

Wikipedia is not a reliable source as anyone can change a wikipedia article. I would say that the largest number ever factored by a quantum computer is much larger then 143, likely millions of times larger. Most personal computers/laptop could likely factor much larger numbers.

That's a baseless opinion.

You're missing the point:  If personal computers can factor bigger numbers, then quantum
computers are LESS effective than classical computers because the technology doesn't currently
work at any scale.  

Although I do agree, wikipedia can't always be trusted.

[evoked22]

I am sure they would have a much better use for this quantum computer than to attempt to ruin and capture a currency that is used all over. They could use the same computer to take over global finances, stocks and shares along with many other things.

I think all will be fine

Shed some light on this if you think otherwise.

[BusyBeaverHP]

New largest number factored on a quantum device is now 56,153.

http://phys.org/news/2014-11-largest-factored-quantum-device.html

"Researchers have set a new record for the quantum factorization of the largest number to date, 56,153, smashing the previous record of 143 that was set in 2012. They have shown that the exact same room-temperature nuclear magnetic resonance (NMR) experiment used to factor 143 can actually factor an entire class of numbers, although this was not known until now. Because this computation, which is based on a minimization algorithm involving 4 qubits, does not require prior knowledge of the answer, it outperforms all implementations of Shor's algorithm to date, which do require prior knowledge of the answer. Expanding on this method, the researchers also theoretically show how the same minimization algorithm can be used to factor even larger numbers, such as 291,311, with only 6 qubits."