What the 'Bitcoin Bug' Means: A Guide to Transaction Malleability
This week, a term emerged that many bitcoiners won't have heard before: transaction malleability. Mt Gox cited it as a key reason for suspending withdrawals, and it was also mentioned as the basis for an exploit used in a massive attack against the bitcoin network this week. So, what is it, how does it work, and should we be worried? Here's what we know. What is transaction malleability? It's an attack that lets someone change the unique ID of a bitcoin transaction before it is confirmed on the bitcoin network. The change makes it possible for someone to pretend that a transaction didn't....
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The Bitcoin Network Under Attack. If you are involved in the Bitcoin ecosystem at all, in the last 72 hours you have been exposed to the phrase "transaction malleability." It's what Mt Gox blamed when it enacted a sudden and prolonged halting of all withdrawals, and it's the vehicle for what has been called a "massive and concerted attack" on various bitcoin exchanges. Transaction malleability had also been a known characteristic of the Bitcoin protocol for a while, as pointed out by many in the community when Mt Gox cited it as a security liability. Despite all of this tumult within the....
One week. Four headline events. Culprit: Transaction Malleability. Although the media grouped the events under the single banner of Transaction Malleability, a closer look reveals that the three incidents involving Mt. Gox, a DDoS attack, Silk Road 2.0 and the Bitcoin client were in fact each unique and in two cases not even related to transaction malleability at all. To understand Transaction Malleability we have to define some terms: Malleability - the quality of being pliable without breaking - often used in reference to metals, but in this context it simply means “changeable without....
For the past several days*, the Bitcoin network has been plagued by a so-called "transaction malleability attack." Bitcoin users have experienced a number of annoyances, causing confusion and frustration. And while the transaction malleability issue is well-known and has plagued the Bitcoin network before, to many it is still unclear what it is, why it is a problem, who is causing the attack right now, and what can be done about it. *According to the claimed attacker (see below), the attack is currently paused at the time of writing, but could and probably will be continued at any time.....
Mark Karpeles pulling a Cassious Coin from behind the photographer's ear. Solid research has proven what many bitcoiners have long suspected; transaction malleability did not play a significant, if any, role in the disappearance of 850,000 BTC from Japanese exchange Mt. Gox. Christian Decker and Roger Wattenhofer of ETH in Zurich, Switzerland, combed through the blockchain to tally each instance of a potential transaction malleability attack in order to figure out exactly how much Bitcoin was put at risk by the alleged attacks. Their research concludes: The transaction malleability problem....
Was a transaction malleability flaw the true cause of over 750,000 BTC belong to Mt. Gox customers going missing? According to a study conducted by Christian Decker and Roger Wattenhofer of ETH Zürich (Swiss Federal Institute of Technology), transaction malleability accounted for significantly less loss than Mt. Gox declared - as little as 386 bitcoins. ...while MtGox claimed to have lost 850,000 bitcoins due to malleability attacks, we merely observed a total of 302,000 bitcoins ever being involved in malleability attacks. Of these, only 1,811 bitcoins were in attacks before MtGox stopped....