Bitcoin Forum

如果真的可以通过公钥找到私钥，那比特币体系就算是玩完了。

量子计算机跟现在的计算机或超级计算机有什么区别，请大神科普一下  :(

量子计算机要是出来不用操心这比特币安全.先着急的是银行.他们的网银也不牢靠，

关键在于黑客能不能买到或者组装量子计算器。

Shor’s algorithm reduces the runtime of cracking elliptic curve cryptography from O(2^k/2) to O(k^3) – that is to say, since Bitcoin private keys are 256 bits long, the number of computational steps needed to crack them goes down from 340 trillion trillion trillion to a few hundred million at most.

If you send a transaction spending all 100 BTC in address 13ign, with 10 BTC going to 1v1tal to pay for goods and 90 BTC change going back to your new address at 1mcqmmnx, the first node that you send the transaction to can replace the change address with whatever they want, recover the private key from your public key, and forge your signature. The only way to get around the problem is essentially to send the transaction directly to a mining pool, like BTCGuild or Slush, and hope that the mining pool will be honest and place the transaction directly into the blockchain. Even then, however, you are vulnerable to a Finney attack – a dishonest miner can forge your signature, create a valid block containing his forged transaction continuing the blockchain from one before the most recent block (the one containing your transaction), and, since the lengths of the old and new blockchains would then be equal, the attacker would have a 50% chance of his block taking precedence. Thus, safe transactions are essentially impossible.

量子计算机（quantum computer）是一类遵循量子力学规律进行高速数学和逻辑运算、存储及处理量子信息的物理装置。当某个装置处理和计算的是量子信息，运行的是量子算法时，它就是量子计算机
其实我也不懂，不过我会问度娘

51%攻击，量子计算危机，比特币其实并不完美，仍是一场试验。

51%攻击，量子计算危机，比特币其实并不完美，仍是一场试验。

我不搞技术不懂这些计算函数，但是关于量子计算机与比特币的问题好像讨论过很多次了，危险真的存在？求解答。

比特币数量排名前10名的比特币地址都在那放着呢. 能找到私钥就去吧. 通过公钥找到私钥那天就是比特币完蛋那天.

51%攻击，量子计算危机，比特币其实并不完美，仍是一场试验。

任何绝对安全的东西只要有人的介入就不会安全了

51%攻击可以理解成股份制公司有人拥有了51%以上的股权，这人对整个公司拥有話事权是无可厚非的

真量子计算机的出现是整个互联网灾难，几乎所有东西都会被推到洗牌，也不缺比特币了

用来挖矿不知道效果如何，一直在想把银河拿来挖矿是什么感觉

就算地址沒花過錢也不安全，危險就在花錢的那一刻，當交易開始廣播的時候，交易可能被不誠實礦工攔截，直接把私鑰破解，然後就呵呵

热力学第二定律的影响之一是,表示信息需要一定数量的能量，通过改变系统的状态记录一个比特位需要的能量不少于kT,其中T是系统的绝对温度，k是波兹曼常数（继续听我说，物理课快要结束了）

鉴于k = 1.38×10^-16 尔格 / K,
宇宙的环境温度是3.2K,理想的电脑运行在温度为3.2K的环境里，每次设置或清除一个比特位会消耗3.2×10^-16尔格能量，在比宇宙背景辐射冷的环境中运行计算机，需要额外的能量来运行热泵。

现在,我们的太阳每年输出的能量约为1.21×10⁴¹尔格，对我们理想的电脑，这些能量足够驱动2.7 × 10⁵⁶次单个比特位的状态变化，足够驱动187位计数器遍历其所有值对应的状态变化。
如果我们建造了一个戴森球环绕太阳和捕获其32年所有的能量输出，没有任何能量损失，我们可驱动计算机计算到 2¹⁹²次状态变化，当然，没有能量剩下来执行其他任何有用的计算。

但这只是一颗星星,微不足道。一颗典型的超新星释放10⁵¹尔格的能量（这个能量约为中微子释放能量的一百倍，中微子的能量暂不考虑）,如果所有这些能量可以引导用于一个密集的运算,可以遍历一个219位的计数器的所有状态。

这些数字与具体的硬件技术无关，这只是热力学允许的最大值，
这强烈表明：暴力攻击256位密钥是不可行的，除非电脑由某种非物质的东西制造并可存放于不是空间的地方。

暴力攻击比特币私钥是不可行的。
对于这一点，布鲁斯·施奈尔教授在其著作“应用密码学”中的一篇文章最有说服力。
在这里，翻译成中文与诸位分享。

表示信息需要一定数量的能量，通过改变系统的状态记录一个比特位需要的能量不少于kT,其中T是系统的绝对温度，k是波兹曼常数

Applied Cryptography - Bruce Schneier

One of the consequences of the second law of thermodynamics is that a certain amount of energy is necessary to represent information. To record a single bit by changing the state of a system requires an amount of energy no less than kT, where T is the absolute temperature of the system and k is the Boltzman constant. (Stick with me; the physics lesson is almost over.)

Given that k = 1.38 × 10⁻¹⁶ erg/K, and that the ambient temperature of the universe is 3.2 Kelvin, an ideal computer running at 3.2 K would consume 4.4 × 10⁻¹⁶ ergs every time it set or cleared a bit. To run a computer any colder than the cosmic background radiation would require extra energy to run a heat pump.

Now, the annual energy output of our sun is about 1.21 × 10⁴¹ ergs. This is enough to power about 2.7 × 10⁵⁶ single bit changes on our ideal computer; enough state changes to put a 187-bit counter through all its values. If we built a Dyson sphere around the sun and captured all its energy for 32 years, without any loss, we could power a computer to count up to 2¹⁹². Of course, it wouldn't have the energy left over to perform any useful calculations with this counter.

But that's just one star, and a measly one at that. A typical supernova releases something like 10⁵¹ ergs. (About a hundred times as much energy would be released in the form of neutrinos, but let them go for now.) If all of this energy could be channeled into a single orgy of computation, a 219-bit counter could be cycled through all of its states.

These numbers have nothing to do with the technology of the devices; they are the maximums that thermodynamics will allow. And they strongly imply that brute-force attacks against 256-bit keys will be infeasible until computers are built from something other than matter and occupy something other than space.

brute-force attacks against 256-bit keys will be infeasible until computers are built from something other than matter and occupy something other than space.

我不搞技术不懂这些计算函数，但是关于量子计算机与比特币的问题好像讨论过很多次了，危险真的存在？求解答。

如果真的可以通过公钥找到私钥，那比特币体系就算是玩完了。