策劃、編譯■劉耘

東京一間交易所內，將近5億美元（約新台幣150億元）價值的虛擬貨幣比特幣憑空蒸發了；這可能是本世紀最大一宗銀行搶案，或是粗心大意的差錯，也可能兩者皆是。

（上圖）東京Mt. Gox官方總部先前所在的建築前，自稱是虛擬貨幣交易商的勃吉斯（Kolin Burges，右）及抗議者亞倫（Aaron）26日拿著標語抗議。（圖文／路透）

比特幣交易平台Mt. Gox曾掌握世上約80％的比特幣交易，但就在2月28日稍晚，28歲的法籍執行長卡伯列向東京地方法院聲請破產。

他的律師表示，這間交易所擁有的85萬枚比特幣幾乎全數消失。卡伯列將之怪罪到駭客頭上。

按其他交易所目前的比特幣匯率計算，這相當於4.73億美元（新台幣141.9億元）損失，約占世上所有開挖出的比特幣7％。

美國杜克大學福夸商學院教授哈維表示：「若竊案屬實，這將會是史上最大一宗銀行搶案。」與2003年海珊令其子從伊拉克中央銀行領出10億美元（約新台幣3百億元）一事不相上下。

這起事件的發生經過至今仍迷霧重重，但多數觀察家表示，Mt. Gox交易所的鬆懈是造成這場災難的主因。

「當我首次加入時，它很明顯地不適用於金融服務公司。」於英國華威大學研究並講授比特幣的拉什曼說道。

但他表示，情況有所改善。「這是個邊做邊學的過程，去發掘各種他們該做卻沒做到的事。」

除了怪罪駭客及Mt. Gox系統的缺陷，目前官方還未提出任何說明。

而網路上流傳一份自稱是代表Mt. Gox準備的危機策略文件，則怪罪這次疏漏是一起「與應變機制相關並潛伏多年的竊案」。

Mt. Gox尚未證實這份文件屬實。

波士頓大學學者海爾曼表示，這個詞彙指的是比特幣交易過程中的一個漏洞，使投機者得以騙過Mt. Gox，令其以為一筆交易失敗，進而不斷重複交易。

儘管這個漏洞已被發現許久，其他交易所也已經修復這個問題，海爾曼及其他人表示，這是對這筆金錢消失的合理解釋。

不過，這份文件提出的解釋中，點出了一個更嚴重的問題。

通常比特幣的密鑰（也就是類似銀行帳戶個人身分認證碼的代碼）是離線儲存的，駭客無法取得。

這種被稱作「冷資料儲存」的資料不會與線上的「熱錢包」金庫連結。

但這份文件表示：「由於線上熱錢包的疏漏，冷資料儲存已被移除。」許多專家認為這個說法並不合理。

若這個解釋屬實，那代表Mt. Gox絕大多數的比特幣存款都已在無人察覺的情況下外洩了。

新加坡「鑄幣銷售」公司的弗傑克表示：「若這種外洩情況長期存在且無人察覺，那將顯露出，此交易所無能到令人不可置信。」

波士頓大學的海爾曼表示，若比特幣真的被偷了，竊賊或竊盜集團將錢幣洗成現金的方式有數種。

他們可透過「混合服務」，將一筆資金與其他人的混在一起。

也能使用像「當地比特幣」這種將個人比特幣轉為現金的服務。

「要換成現金的可能途徑有許多種，但要掩飾這麼大一筆的比特幣交易非常困難。」他說。

要得知這到底是一場搶案、人為疏失或兩者的綜合需要時間，但也可能永遠成謎。

美國聯邦檢察官已傳喚Mt. Gox及其他比特幣交易所，以尋求更多資訊、了解大批突如其來的嚴重駭客攻擊。

然而，在上海經營金融顧問公司的卡普隆表示，未受規範的比特幣產業無需技術審核或風險管理程序，起訴那些潛在違法者的方式也不多。

「不幸的是，我們可能永遠也無法得知這怎麼發生的。」（路透）

註：Mt. Gox是Magic: The Gathering, Online eXchange的縮寫，它的前身是電玩《魔法風雲會》的線上交易站，在2010年轉為比特幣交易平台。

▲Mt. Gox比特幣交易所28日在東京地方法院舉行記者會，執行長卡伯列在記者會開始時鞠躬道歉，圖由日本《共通社》拍攝。（圖文／路透）

相關閱讀

【看好比特幣 狂熱者信心不減】http://www.lihpao.com/?action-viewnews-itemid-138173

【爭經濟主權 美原民發行虛擬幣】http://www.lihpao.com/?action-viewnews-itemid-138172

Close to half a billion dollars worth of the bitcoin virtual currency（1） has gone missing from an exchange in Tokyo - in what is either the bank heist of the century or a sloppy glitch（2）, or a combination of the two.

Mark Karpeles, the 28-year-old French CEO of Mt. Gox, which once handled around 80 percent of the world's bitcoin trades, filed for bankruptcy at a Tokyo District Court late on Friday.

His lawyer said that nearly all the bitcoins in the exchange's possession - 850,000 of them - were missing. Karpeles blamed hackers.

At current bitcoin rates on other exchanges, that would mean $473 million is lost - around 7 percent of all bitcoins minted.

"If the theft is true," said Campbell Harvey, a professor at Duke University's Fuqua School of Business, "it's the biggest bank heist（3） in history," aside from when Saddam Hussein ordered his son to withdraw $1 billion from Iraq's central bank in 2003.

How this happened remains a mystery. But most observers say Mt. Gox's laxness（4） played a key role in the debacle（5）.

"When I first signed up to it, it was clearly not fit to be a financial services company," said Jon Rushman, who researches and lectures about bitcoin at England's University of Warwick.

But things got better, he said: "It has been a process of learn-by-doing that they have discovered all sorts of things they should be doing, but were not."

No official explanation has been forthcoming beyond blaming hackers and weaknesses in Mt. Gox's system.

A document circulating on the internet that purports to be a crisis strategy paper prepared on behalf of Mt. Gox blamed the hole on a "malleability-related theft which went unnoticed for several years."

Mt. Gox has not confirmed the authenticity of the document.

The phrase, says Ethan Heilman, a research fellow at Boston University, refers to a bug in the bitcoin process whereby someone could trick Mt. Gox into thinking a transaction had failed - and therefore keep repeating it.

This, say Heilman and others, could explain the disappearance of the money - even though the bug has been known for a while, and has been fixed on other exchanges.

More problematic is another part of the document's purported explanation.

Usually bitcoins' private keys - something similar to a personal bank PIN code - are stored offline, where hackers can't get them.

This 'cold storage' is unconnected to the online part - the hot wallet.

The document says "the cold storage has been wiped out due to a leak in the hot wallet" - a statement experts say doesn't make sense.

If true, this suggests the vast majority of Mt. Gox's bitcoin deposits were leaking out without anyone noticing.

At Singapore-based Coin Of Sale, Tomas Forgac said: "If this was long-term leakage which went unnoticed, it shows an unbelievable level of incompetence."

If the bitcoins have been stolen, the thief or thieves would have several options to convert them into cash, said Boston University's Heilman.

They could have used a "mixing service" to mix one group of funds with those of other people.

They could also have used a service like localbitcoins.com to trade bitcoins for cash in person.

"There are many possibilities for cashing out, although fencing this many bitcoins would be difficult," he said.

Knowing whether this was theft or negligence, or both, will take time, and may never happen.

U.S. federal prosecutors have subpoenaed Mt. Gox - and other bitcoin businesses - to seek information on a spate of disruptive cyber attacks.

But bitcoin is an unregulated industry, requires no technical audits or risk management procedures - and offers few ways of prosecuting those who might have acted illegally, says Zennon Kapron, who runs a finance consultancy in Shanghai.

"The unfortunate part is that we may never know exactly how this happened," he says.（Reuters）

1.virtual currency （n.）虛擬貨幣

2.glitch（n.）故障

3.heist（n.）搶劫

4.laxness（n.）鬆懈

5.debacle（n.）崩潰；災難