Posts Tagged ‘MtGox withdraws


In a previous statement regarding the situation with the suspended BTC withdraws at MtGox the company has said that this Thursday (today) they could restore the normal operations including BTC withdraws as they have worked on a workaround to prevent fraudulent use of the reported malleability issue with BTC transactions. Today however they have released an update on the situation and they still haven’t restored normal BTC withdraw operations while meanwhile the exchange rate of BTC at MtGox continues to fall and is closing to $100 USD mark. The good thing is that the exchange rate of BTC in other major exchanges has stabilized already and is not affected that much by MtGox’s very low rate because of the BTC withdraws being suspended there for a while already. Below is the official statement from MtGox from today:

Thank you for your patience this week while we are working on re-initiating bitcoin withdrawals. In addition to the technical issue, this week we have experienced some security problems, and as a result we had to relocate MtGox to our previous office building in Shibuya (details can be found here The move, combined with some other security and technical challenges, pushed back our progress.

As much as we didn’t want to only provide an “update on an update”, this is the current status. We are committed to solving this issue and will provide more information as soon as possible to keep everyone in the loop.

We are very sorry for the delays and deeply appreciate your kind understanding and continuous support.

Best regards,
MtGox Team


MtGox has released an official statement today that they will be resuming full operations soon as they have apparently implemented a solution that should enable withdrawals and mitigate any issues caused by transaction malleability. MtGox apparently has developed a workaround that will use a unique identifier created by Blockchain to show whether transactions have been modified or not. This is supposed to prevent any fraudulent use of the malleability issue and protect the assets of MtGox customers.

Resuming Withdrawals
With this new system in place, MtGox should be able to resume withdrawals soon. At the beginning we will do so at a moderated pace and with new daily/monthly limits in place to prevent any problems with the new system and to take into account current market conditions.

In order to launch the new system, we are going through the following steps:
– Re-indexing the entire Blockchain (approx. 32 million entries)
– Fully deploying the new NTX ID
– Implementing a new bitcoin withdrawal queue that needs to be tested
– We will update everyone again by Thursday at the latest.

Additionally, you may have noticed that we have added a new login system that sends you an email when you successfully access your account. This is an additional security layer, but as always we strongly encourage our customers to use the 2-step authorization options available in our Security Center.

Hopefully this will help in stabilizing BTC exchange rate in the next few days, especially after MtGox resumes full trading operations including BTC withdraws and this will calm the situation that has gone crazy. Bitstamp has already restored their automated Bitcoin withdraws, so this announcement from MtGox should also help in restore things back to normal.


It seems that MtGox will be suspending the BTC withdraws from their system for a longer period of time due to an issue discovered in the Bitcoin transaction method currently in use. The issue is not limited to MtGox, and affects all transactions where Bitcoins are being sent to a third party. So for now MtGox is not going to resume the BTC withdraws from their system, though deposits and currency withdrawals are not going to be affected. As a result the BTC exchange rate is continuing to drop on the MtGox exchange as well as on other exchanges. Below you can read the official statement from MtGox:

Dear MtGox Customers and Bitcoiners,

As you are aware, the MtGox team has been working hard to address an issue with the way that bitcoin withdrawals are processed. By “bitcoin withdrawal” we are referring to transactions from a MtGox bitcoin wallet to an external bitcoin address. Bitcoin transactions to any MtGox bitcoin address, and currency withdrawals (Yen, Euro, etc) are not affected by this issue.

The problem we have identified is not limited to MtGox, and affects all transactions where Bitcoins are being sent to a third party. We believe that the changes required for addressing this issue will be positive over the long term for the whole community. As a result we took the necessary action of suspending bitcoin withdrawals until this technical issue has been resolved.

Addressing Transaction Malleability
MtGox has detected unusual activity on its Bitcoin wallets and performed investigations during the past weeks. This confirmed the presence of transactions which need to be examined more closely.

Non-technical Explanation:
A bug in the bitcoin software makes it possible for someone to use the Bitcoin network to alter transaction details to make it seem like a sending of bitcoins to a bitcoin wallet did not occur when in fact it did occur. Since the transaction appears as if it has not proceeded correctly, the bitcoins may be resent. MtGox is working with the Bitcoin core development team and others to mitigate this issue.

Technical Explanation:
Bitcoin transactions are subject to a design issue that has been largely ignored, while known to at least a part of the Bitcoin core developers and mentioned on the BitcoinTalk forums. This defect, known as “transaction malleability” makes it possible for a third party to alter the hash of any freshly issued transaction without invalidating the signature, hence resulting in a similar transaction under a different hash. Of course only one of the two transactions can be validated. However, if the party who altered the transaction is fast enough, for example with a direct connection to different mining pools, or has even a small amount of mining power, it can easily cause the transaction hash alteration to be committed to the blockchain.

The bitcoin api “sendtoaddress” broadly used to send bitcoins to a given bitcoin address will return a transaction hash as a way to track the transaction’s insertion in the blockchain.
Most wallet and exchange services will keep a record of this said hash in order to be able to respond to users should they inquire about their transaction. It is likely that these services will assume the transaction was not sent if it doesn’t appear in the blockchain with the original hash and have currently no means to recognize the alternative transactions as theirs in an efficient way.

This means that an individual could request bitcoins from an exchange or wallet service, alter the resulting transaction’s hash before inclusion in the blockchain, then contact the issuing service while claiming the transaction did not proceed. If the alteration fails, the user can simply send the bitcoins back and try again until successful.

We believe this can be addressed by using a different hash for transaction tracking purposes. While the network will continue to use the current hash for the purpose of inclusion in each block’s Merkle Tree, the new hash’s purpose will be to track a given transaction and can be computed and indexed by hashing the exact signed string via SHA256 (in the same way transactions are currently hashed).

This new transaction hash will allow signing parties to keep track of any transaction they have signed and can easily be computed, even for past transactions.

We have discussed this solution with the Bitcoin core developers and will allow Bitcoin withdrawals again once it has been approved and standardized.

In the meantime, exchanges and wallet services – and any service sending coins directly to third parties – should be extremely careful with anyone claiming their transaction did not go through.

Note that this will also affect any other crypto-currency using the same transaction scheme as Bitcoin.

To put things in perspective, it’s important to remember that Bitcoin is a very new technology and still very much in its early stages. What MtGox and the Bitcoin community have experienced in the past year has been an incredible and exciting challenge, and there is still much to do to further improve.

MtGox will resume bitcoin withdrawals to outside wallets once the issue outlined above has been properly addressed in a manner that will best serve our customers.

More information on the status of this issue will be released as soon as possible.

We thank you for taking the time to read this, and especially for your patience.

Best Regards,
MtGox Team