近期，以太坊经典（ETC）遭受了一次51%攻击，攻击者利用其较小的市场规模和较低的算力，成功篡改了区块链，并盗取了价值数十万美元的ETC。此次攻击引发了人们对加密货币安全性的担忧，以及对工作量证明（PoW）与权益证明（PoS）共识机制的争论。

😁 **以太坊经典51%攻击的背景:** 以太坊经典（ETC）的市场规模较小，算力相对较低，使其容易受到51%攻击。攻击者通过租用算力，控制了超过50%的网络算力，从而成功篡改了ETC区块链，并盗取了价值数十万美元的ETC。

🤔 **对交易所的影响:** 此次攻击对交易所产生了重大影响，因为交易所需要决定是否继续支持像ETC这样容易受到攻击的加密货币。一些交易所，如Coinbase，已暂停了ETC交易，以保护用户资金安全。

🚀 **工作量证明与权益证明的争论:** 此次攻击也引发了人们对工作量证明（PoW）与权益证明（PoS）共识机制的讨论。PoW机制依赖于算力，而PoS机制则依赖于持有代币的份额。PoS机制被认为更安全，因为攻击者需要控制大量的代币才能发动攻击。

🧐 **以太坊经典攻击的启示:** 以太坊经典攻击表明，即使是较小的加密货币也可能成为攻击者的目标。这提醒我们，加密货币安全是一个需要持续关注的问题。

💡 **对未来加密货币发展的影响:** 此次攻击也为未来加密货币的发展提供了启示。为了提高安全性，加密货币需要采用更强大的共识机制，并不断完善安全措施。此外，交易所也需要加强对加密货币的审查，以确保用户的资金安全。

In Special Episode of Hidden Forces, Demetri Kofinas speaks with Haseeb Qureshi of MetaStable Capital about the recent 51% attack against Ethereum Classic, its implications for exchanges that continue to list smaller market-cap cryptos like ETC, Dash, Monero, etc., and what it means for the debate between proof-of-work and proof-of-stake.

On January 5th, 2019, the digital currency exchange Coinbase detected a deep chain reorganization of the Ethereum Classic blockchain. In order to protect customer funds, they immediately paused interactions with the ETC blockchain. Coinbase reported the 51% attack on January 7, 2019, but a few people on Twitter had already become aware that something wasn’t right with ETC. Pierre Rochard, an emerging thought-leader in the Bitcoin space, asked ETC developer Donal McIntyre on Twitter:  “Was there a deep reorg on Ethereum Classic yesterday?… 75 blocks deep I hear, with a double-spend.” Donal McIntyre replied: “Well ETC is still small and has many enemies so an attack with sufficient GPU power may be plausible, but I will check with others in the ecosystem.”

Cryptocurrencies that are not dominant in their respective mining algorithm, especially ones for which hashing power can be easily rented out, are more vulnerable to being 51% attacked than are other cryptocurrencies with larger market-caps that are not ASIC-resistant. According to Charlie Lee, founder of Litecoin, “ETC has less than 5% of the total Ethash hashrate and is 98% NiceHash-able. 1-hr attack costs $5k,” making it particularly vulnerable according to these two metrics.

Reports of the amount stolen in the attack range from the low six-figures to over one million dollars worth of ETC. Perhaps what is most remarkable is that this is only the latest 51% attack against a smaller-cap currency where the attack did not materially impact the price of the cryptocurrency in question.

Demetri and Haseeb explore the reasons why the price of ETC was largely unaffected, what this latest attack means for the listing (or delisting) of similarly sized cryptocurrencies, and how this is sparking a larger debate about the efficacy of proof-of-work vs. proof-of-stake as mechanisms for securing a cryptocurrency.

Producer & Host: Demetri Kofinas

Editor & Engineer: Stylianos Nicolaou

Join the conversation on Facebook, Instagram, and Twitter at @hiddenforcespod