《The Sidechains Breakthrough Almost Everyone in Bitcoin Missed》
《比特币世界几乎都没有察觉的侧链技术突破》

[Alyssa Hertig]
Jan 17, 2018 at 05:00 UTC

You've heard of proof of work, but what about proofs of proofs of work?
想必你听说过工作量证明了，那么工作量证明的证明呢？

A complex notion, the research on "Non-Interactive Proofs of Proofs of Work," or NiPoPoW, released in October, has received very little attention so far but is heralded as breaking through one of the major roadblocks that has stalled the widely anticipated sidechain technology.
这是一个有点复杂的概念，一项对于“非互动工作量证明之证明”，或简称NiPoPoW的研究成果于10月发布，尽管目前并无多少人关注，但却被预言可能突破那些阻碍广受期待的侧链技术进展的其中一个难点。

In the paper, researchers from IOHK, IC3 and the University of Athens describe a mechanism for proving that data exists in the bitcoin blockchain in a more efficient way.
在白皮书中，来自IOHK，IC3和雅典大学的研究者们描述了一种机制，可用更高效的方式来验证比特币区块链中存在的数据。

Though the idea can be useful in more than one context, it's perhaps most exciting in the way the researchers describe the proofs' benefits for sidechains, a technology that pegs other blockchains to bitcoin, which some, because of its obstacles, have called vaporware, but that others refer to as the "altcoin killer."
这个想法在不少场景中都很有用，但最让人觉得兴奋的莫过于研究者们描述的，该证明机制对侧链技术的帮助。侧链技术是一种可将其他区块链锚定到比特币区块链上的技术，被人们称为“竞争币杀手”，但因为各种障碍也被一些人称为“雾件”（看得见却摸不着产品或服务）。

Sidechains seek to solve a vexing problem – that adding features to bitcoin is a dangerous process since $230 billion of value is at risk if the new feature doesn't work or malfunctions in practice.
侧链技术寻求的是解决一个老大难的问题——在比特币上增加功能困难重重，如果新功能不起作用或者在运行中失灵了，那对这个2300亿美元市值的币种是非常危险的事情。

Instead of adding new features directly to the bitcoin blockchain, sidechains allow developers to attach new features to a separate chain. Since the chains are still attached to the bitcoin blockchain, the features can take advantage of the cryptocurrency's network effects and test those applications, without harming the main network should vulnerabilities arise.
比起在比特币的区块链上直接添加功能，侧链技术可让开发者们在一条单独的链上添加新功能。因为这些侧链还是锚定在比特币区块链上，所以这些新功能可以利用加密货币的网络效应并测试这些应用，同时又不伤及主网络的脆弱性。

Because of this, sidechains were met with excitement initially, but has faced contention since many have concerns about the security of the technology.
正因如此，侧链技术在最初很令人兴奋，但随着不少人担心该技术的安全性也遭遇到争论。

Even still, some engineers have been grinding away at a parallel version of the technology that tries to rely on better economic incentives to make sidechains more secure, yet some developers remain skeptical they're ready to add to the bitcoin network.
甚至当一些工程师转而去开发一个相似的版本，并试图依靠更好的经济激励方式让侧链更加安全，却还是受到了一些开发者质疑他们是否已准备好可被添加到比特币网络中。

But skeptics see this NiPoPoW research as a big step.
但如今怀疑者们也将NiPoPoW的研究看做重要的一步。

Blockstream's Mark Friedenbach, who co-authored the original sidechains white paper, first proposed in 2014, told CoinDesk:
Blockstream的Mark Friedenbach，是2014年发布的侧链技术初始白皮书的合著者，他告诉Coindesk：

"This moves the ball down the field significantly."
"这让球在球场上起了很大变化"

Securing sidechains

加固侧链

The paper helps move forward the idea of trustless sidechains, over the more centralized type of sidechains – where the movement of funds of a federated sidechain is governed by a few companies – used today.
这论文将去信任化的侧链技术的想法向前推进了，超越了如今多在使用的中心化类型的侧链技术，这种侧链技术结成联盟，其中的少数公司掌控了资金的流动。

While a simple idea, trustless sidechains are hard to put into practice.
但同时，这个简单的想法—去信任化的侧链技术还很难实用起来。

They rely on a technology called SPV (simplified payment verification) proofs, which work like this: in order to send money to a sidechain and back to the main bitcoin network again, users need to attach a proof that they really have the funds. Without these proofs, when users or miners move their money back to the main chain, under certain conditions, they could take more money than they really have.
因为侧链技术依靠一个称为SPV（简单支付验证）证明的技术，它是这么运行的：为了向侧链中发送资金并且返回到比特币主网中，用户需要随附一份他们确实有这些资金的证明。若没有该证明，当用户或者矿工将资金移回主链时，在某种情况下，他们可以取走比实际更多的资金。

These proofs need to do two things before the technology can be added to bitcoin: one, prevent this sort of theft, and two, be small enough that they can actually be sent over the network.
在该技术可被添加到比特币上之前，这“证明”需要完成两件事情：1.防止这种类型的盗窃行为，2.需要足够小巧，来确保他们可被发送到网络中。

While so-called "compact SPV proofs" have been proposed, they've proved vulnerable to certain attacks, ones that would potentially allow miners to steal money left on the sidechains.
可当所谓“坚固的SPV证明”被提出之时，它们也被证明了在一些攻击面前还很脆弱，其中一些攻击让矿工们有可能窃取侧链中的资金。

Yet, the proof outlined in the NiPoPoW paper claims to be resistant to these attacks.
不过在NiPoPoW中提出的证明框架宣称能抵挡这些攻击行为。

"It's the first protocol, to my knowledge, which makes [sidechains] secure at all," University of Athens cryptography Ph.D. candidate Dionysis Zindros, one of the co-authors of the paper, told CoinDesk.
“以我所知，这是第一个可使侧链技术彻底变得安全的协议，”雅典大学加密学博士生Dionysis Zindros如此告诉CoinDesk，他也是该论文的合著者。

He went on to explain that by "secure" he really means resistance to double spending, where users or miners could spend their coins more than once.
他继续解释说“安全”是指真的可以抵抗双重支付，就是用户或者矿工可以把他们的货币使用不止一次。

"It's really a missing piece in sidechain constructions that we fill in," Zindros said.
“我们所填补的真的是侧链结构中缺失的一部分。”Zindros说到。

Friedenbach described the change in more technical terms: "This is a big step towards defining a block header commitment structure that allows for log-sized chain proofs, of the sort that one might use in a decentralized sidechains implementation."
Friedenbach用更多科技术语来描述：“这对定义区块头的承诺结构是重要的一步，因为可让侧链证明以日志文件的大小存在，而这是一个去中心化的侧链技术更可能实施的类型条件。”

Work ahead

奋发进取

While Friedenbach calls NiPoPoW "good research," he added, work remains before the technology can be deployed on bitcoin.
当Friedenbach称NiPoPoW为“好的研究”的时候，他补充道，在该技术能在比特币中部署之前，还有很多工作要完成。

This is a recurring theme in the cryptocurrency world, where developers are careful about making changes to the still young and novel code. And while sidechains look to make the process of trying out new features easier and less nerve-wracking, implementing even that will take further deliberation.
这在加密货币的世界里是一个反复的话题，因为这个领域的开发者们对在仍然小众与早期的代码中做改变是非常谨慎的。即便侧链技术看起来让尝试新功能的过程变得更容易更不那么令人心烦，在其中实施仍然很需要长远的思考。

For one, to make sidechains more secure, many developers believe merge-mining – when miners mine multiple coins at the same time – would be essential.
比如说，为了让侧链技术变得更加安全，很多开发者相信共同挖矿—就是矿工们同时挖不同的货币—也就变得很重要了。

"There is still significant scripting capabilities that would be required before merge-mined SPV-proof sidechains could be supported on bitcoin mainnet," Friedenbach said.
“在比特币主网支持基于共同挖矿的SPV证明侧链技术以前，还需要很重要的代码开发能力，”Friedenbach说道。

But there are other worries around merge-mining that are more paramount.
不过围绕着共同挖矿还有其他更深的担忧。

"There is also, of course, the non-trivial incentive problem of merged-mining and whether such a solution would be a step back in security, given the current state of the oligarchical mining industry," Friedenbach added.
“当然还有包括共同挖矿的可观的激励问题，以及这种方案会不会是安全性上的倒退，考虑到现在挖矿业中的寡头情况。”Friedenbach说道。

In many's view, since the industry relies on the work of a few large mining pools, it could be possible for these miners to have significant control over sidechains, and it's not yet clear whether mining pools would have the power to steal funds.
在大多数人的看法中，既然该产业依赖于少数几个大矿池的运作，那么这些矿工们也很可能对侧链技术进行严重的控制，到目前还不清楚矿池有没有能力窃取资金。

That said, this piece of the puzzle is exciting to Friedenbach, even though buzz around the paper has been subdued.
总而言之，这块拼图让Friedenbach感到十分兴奋，尽管围绕着该论文还有不少的议论之声。

He concluded:
他总结到：

"This idea deserves more attention."
“这个想法值得更多的关注”

*Disclosure: CoinDesk is a subsidiary of Digital Currency Group, which has an ownership stake in Blockstream. *