该缺陷对比特币本身的影响并不大，因为它存在于交易所系统上。许多交易使用TX-ID来作为唯一标识，但事实证明，攻击者可以在不改变实际交易的情况下改变TX-ID，重置交易（有效地创建一个双重支付），如果在合理操作的前提下改变交易，那么攻击者将收回他的比特币，并且抱怨这次未完成的交易。该交易所将检查他们的数据库，从中提取TX-ID，看看是否能在blockchain中找到它，当然他们并不会找到它。这样他们就可以得出结论，该交易确实是失败的，将会向该攻击者的信用账户返还比特币。
一个简单的解决方法就是不使用TX-ID来标识交易，而通过使用金额、地址、时间戳来代替。如果用户抱怨他们的交易没有完成且没有收回投入的比特币，那么交易所完全可以通过金额、地址、时间戳来审查此次交易。虽然这需要工作量上的一点点支持，但它可以有效防止这种恶意攻击的得手。
虽然TX-id协议本身的延展性并不好，但将问题归结于该协议的缺陷显然是一个很好的托词。
我问Greg Maxwell 是否同意上述总结。他的回答是：
我不反对，但实际上这个话题缺少一个零界点，我仅仅是为了及时更新比特币的最新发展状况。关于上面提到的比特币最新发展状况，DRAK提出了以下问题：
2014年2月10日也就是周一上午3:28，DRAK写道：MT.Gox核心开发人员针对公司声明中将过错归结于比特币钱包客户端而不是公司的说法作出了正式回应。比特币钱包客户端的一些旧版本在处理未确认的交易时存在问题，但这个问题在2011年就已经发现了。这次的事故完全由Mtgox自己的内部系统造成。
技术人士分析，MtGox将过错归结于钱包只是这个烂摊子开始的前兆。 （比特币之家刘友-smile、那谁儿合译，转载请注明出处）
英文原文：
Mt. Gox Official StatementMt. Gox have just released their official statement regarding their recent decision to halt all Bitcoin withdrawals.Essentially, they are claiming they can’t release customers’ funds until a known bug in the Bitcoin protocol is resolved.
The market is reacting very negatively to the Gox announcement, falling ~$160 on high volume since the news.
Greg Maxwell RespondsI spoke with Bitcoin core developer, Greg Maxwell, about this highly technical issue. Greg Maxwell and Peter Wuille are the core developers in consultation with Mt. Gox, as per their press release. The Gox press release seems a little ‘spun’ to me. They portray characteristics of the Bitcoin system well known since at least 2011 (which even have their own wiki page ) as something new.These characteristics are annoying but don’t inhibit basic operation. They are slowly being fixed – but fixing them completely will likely take years as they require changing all wallet software. Correctly-written wallet software can cope with the consequences, and I cannot understand why they would gate their withdraws on external changes. Andreas Antonopoulus has examined Gox’s code to some degree, and remarked that they are using a strange “hodgepodge of technologies that are really not suitable for running an exchange.” Do you believe the problem lies in their code rather than the Bitcoin protocol? Oh there is a “problem” in the Bitcoin protocol, known since at least 2011 (see the link I gave). But for normal applications, not involving unconfirmed transactions, it shouldn’t cause any severe problems because wallets can handle it locally.Basically, third parties can change the transaction IDs of transactions. This means what wallet software must be written to accomodate that and still recognize them when that happens.What the press release talks about is adding a second kind of transaction ID, which is robust against changes, which would be helpful for tech support purposes. Though it doesn’t resolve all of the issues that being able to modify transactions presents. So in other words, Gox should be able to account for this known problem by modifying their internal systems? Yes, internal only changes should account for it. The only remaining issue for Mt. Gox’s application would be some tech support problems, where if a user’s transaction is mutated by a malicious party the txid ["transaction ID"] Mt. Gox told them to expect wouldn’t be the one that ultimately showed up in the blockchain. It seems the market is reacting very negatively to the news. What advice would you give to the average Bitcoiner regarding this situation? The challenge for me in offering something here is that this isn’t news to me – for years – and it’s never been a particularly large concern. This wouldn’t make the top ten list of dangers in the Bitcoin technology. Thanks for your comments.-Update 1: Market StabilisingAs of 13:35 GMT+2, the market has retraced about 60% of the recent loss as the news is digested.In my personal opinion, Gox have done more harm to the Bitcoin community than good to themselves through their statement. This situation should have been handled in such a way as to minimize the market impact.
Bitstamp 30 minute chart.
Update 2: Further technical details.In a BitcoinTalk thread relating to Mt. Gox’s statement, Rannasha offers this concise summary of the situation:The flaw isn’t so much in Bitcoin as it is in exchange-systems. Many exchanges use the tx-id to uniquely identify transactions, but as it turns out, an attacker can change the tx-id without changing the actual transaction, rebroadcast the changed transaction (effectively creating a double-spend) and if his altered transaction gets accepted into a block instead of the legit transaction, the attacker receives his coins and can complain with the exchange that he didn’t. The exchange will then check their db, fetch the tx-id from it, look it up in the blockchain and not find it. So they could conclude that the transaction indeed failed and credit the account with the coins.A simple workaround is to not use the tx-id to identify transactions on the exchange side, but the set of (amount, address, timestamp) instead. If a user complains about not receiving their withdrawal, support can look it up using these 3 variables. It takes a little bit more work from support, but it prevents this attack from succeeding.While it’d be nice if the tx-id isn’t malleable, blaming this problem on a flaw in the protocol is quite a stretch.
I asked Greg Maxwell whether he agreed with this summary. His reply:I don’t disagree but it’s actually missing a critical point on that subject that I posted about on Bitcoin-development just now.
As per the above link, Drak posed the following question:On Mon, Feb 10, 2014 at 3:28 AM, Drak wrote: What is the official response from the Bitcoin Core developers about MtGox’ assertion that their problems are due to a fault of bitcoin, as opposed to a fault of their own?The technical analysis preluding this mess, was that MtGox was at fault for their faulty wallet implementation.
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