Hot answers tagged

30

Fungibility. Money needs to be fungible, otherwise it's not money at all. Blacklists allow censorship and confiscation of wealth by centralized/powerful players (like governments) which will be abused to screw over innocent people Or (hopefully) scare those people away from Bitcoin in the first place: why would you invest in Bitcoin if you know you could ...


26

Bitcoin strongly enforces two concepts - high anonymity and no chargebacks. Because of high anonymity, it is nearly impossible to be 100% certain who you are sending Bitcoins to. In the end, the Bitcoin address is just an arbitrary string of characters. Because of no chargebacks, once you send someone Bitcoins, they are irreversibly theirs (assuming no ...


24

ECDSA signatures are pairs (r,s) where r=(kG).x mod n, and s = (m + rx)/k mod n, where x is the secret key, k is the random nonce, and m is the message. If you have two s values s1 and s2 for the same secret key and with the same nonce k (and thus the same value r), the following holds: s1 = (m1 + r*x)/k s2 = (m2 + r*x)/k From that we can derive: s1 * k =...


18

It's because bitcoin transactions are final, and exchange margins are low. Businesses selling something for download can afford to be hit by fraud without incurring any real loss (other than potentially an opportunity cost, but even that is likely to be minimal as fraudsters would be unlikely to pay even if they couldn't defraud). ie margins are high. ...


18

From what it appears, yes, it is possible, and quite simple really to outsource vanity address creation to a third party without risking anything. Bitcoin addresses are created from ECDSA keypairs. Their property is that if you take two private keys and add them together (with appropriate modulo operations), the sum will map to a public key that is the same ...


17

It wouldn't work. Imagine if you get to a grocery store and try to pay in cash and they say, "Sorry, your dollars are no good, their serial numbers are on a list of bills that have been stolen". You might have gotten those dollars in change yesterday from that very same grocery store because that's where the thief spent them before they got on the list. ...


14

Here's a list of the most notable scams, thefts, and hacks: https://bitcointalk.org/index.php?topic=83794


10

Here all famous scammers/sites: List of Known Bitcoin Scams: Beware of Fraudsters! Bitcoin Scammers list


9

The "Linode problem" is storing Bitcoins on a managed device. That managed device might be server hosting from Linode, for example, or a cloud server at RackSpace for another example. In both instances, by simply gaining root access using the service provider's systems, tens of thousands of bitcoins were stolen. The incident in which the "Linode problem" ...


9

Thanks to Elliptic Curve cryptography, a third party doesn't need to know the private key to generate a vanity address, as JoelKatz describes here: http://bitcointalk.org/index.php?topic=81865.msg901491#msg901491


9

All BTC transfers are final. If a hacker moved your BTC elsewhere, you can't get it back. You have to keep your funds safe. See https://en.bitcoin.it/wiki/Securing_your_wallet.


8

Bitcoins are liquid. Everybody wants bitcoins, and as many as they can get - if not for some immediate use, then to sell them for other currencies which are of immediate use. Even someone who doesn't need or believe in Bitcoin can still steal them. Thus a Bitcoin CC trader will attract all the fraudsters in the world. A site like RPGNow will attract only ...


7

There are two very important concepts here: You can only be hurt by someone you chose to trust. A chain only exists instantaneously while a payment is made. The answer to your question depends on whether David pays Charlie or not. If David pays Charlie, then David gets hurt because he trusted Eve and she betrayed him. If David doesn't pay Charlie, then ...


6

Zhou tong has stated here that reopening is being considered, with a time frame of several months. He has also stated that deposits will be refunded; Most recently, he has stated that a claim page has been opened at https://claims.bitcoinica.com/, but at the time of this writing it seems to be unavailable. Update: I can now access it.


6

It really isn't possible to create a blacklist of stolen bitcoins. While it is possible to easily trace stolen bitcoins, thieves can utilize a number of services, such as bitcoin mixing services, that mix stolen bitcoins with other (sometimes even freshly mined) bitcoins before redistributing the bitcoins to new wallet addresses. Because wallets are ...


5

Interesting points Paper, here some of my thoughts... As you said, on the underground (i.e. TOR) there are forums where thieves are selling dirty coins, with a favorable exchange rate (1 clean coin for 2 dirty coins for example). But to avoid scam I suppose they will use some kind of anonymous escrow service to perform the exchange, to guarantee that both ...


5

Selfish Mining cannot be used to change transactions in any way, therefore, it is impossible to steal funds in such fashion. Also, Selfish Mining is somewhat the opposite of Double-Spending, as double-spending would require you to publish your own blocks as quickly as possible in order to overtake the network, while selfish mining is based on keeping ...


5

Bitcoin is decentralized. There is no "we" to appeal to even if we wanted. You may be able to convince a miner to not include txs that go to certain addresses. That is their right. But that certainly won't prevent dealings that are unethical or wrong. That's like saying "why can't merchants not accept stolen $100 bills?" There is a huge tax for everyone if ...


4

This much less likely for a number of reasons: Banks have advanced, robust and well-tested anti-fraud infrastructure, making such thefts much more likely to be detected. Legally it is much much easier to prosecute for fraud cases in fiat than BTC (I do not know any prosecution over stolen Bitcoins) Fiat transactions are reversible meaning the exchange could ...


4

According to MtGox, the hacker got about 2000 BTC. A few real customers also appear to have purchased bitcoins at an artificially low price during the incident, withdrawn them, and kept them. This is estimated to amount to less than 650 BTC. The details given at the above link are: ~June 2011 Mt. Gox Incident Time: 2011-06-19T18:00 ± 1 h (theft), days ...


4

In order of date: 13th June 2011, 25,000 BTC stolen from an early adopter "allinvain": A single user claims they were hacked and lost an enormous quantity of Bitcoins. 15th June 2011, 650 (?) BTC stolen from MtGox exchange: This attack probably made the news more than any other because the apparent market price plunged to $0.01/BTC, but withdrawal limits ...


4

If you look at a graph of the value of 1 bitcoin, that huge spike and drop was caused by someone hacking Mt.Gox and selling everyone's bitcoins to him/her for $0.00, dropping down the value to $0, and it stayed low as more people sold their bitcoins to make sure it wouldn't happen to them. It's been slowly rising since then.


4

You do not need to send coin to another wallet, but you surely need them to be sent to another address (since the compromised wallet has compromised addres). What I would is go to http://blockchain.info and open a new wallet. Copy paste the first address you see, it'll be your new secure address since you just genereted it. Then import your old compromised ...


4

Unless you happen to know who owns 16fYQiV2cdHuycGo3eibE5JSKvndY2z8Gw, there is no way for you to get back your Bitcoin. You could try to raise awareness that this address holds stolen coin, but I don't see how that would benefit you in any way. What happened is essentially the Bitcoin equivalent of somebody taking your dollar bills from your wallet without ...


4

Just to elaborate on the comment by Diego Basch: Of course, Bitcoin has no solution for the fundamental problem that the threat of force can compel a person to do something they don't want to. (Maybe that bug will be fixed in the next version of civilization.) But street robbery should ultimately be less of a risk than you think. Although it's possible ...


3

According to this speculative thread at bitcointalk.org forums, a minimum of 27,000 BTC (worth $370,000 USD at that time), with a possible maximum of 75,000 BTC, estimated. Here's a screen cap of the first post in the thread, in case the forum later disappears:


3

There are many ways theft can occur. Even though the cases where hackers have stolen from exchanges or from individuals, in terms of the number of bitcoins lost that amount is chump change compared to the amount of coins lost to scammers such as PirateAt40 and other scams, including loans not being repaid or currency trades that go bad. But as far as ...


3

The short answer is basically "no". The thief will only hold the stolen coins for a short period of time. After that, it's all in the hands of innocent people. We don't do anything like this with cash. There are no "hot lists" of stolen bill serial numbers that cannot be spent. And for good reason. The big problem for Bitcoin is that we can't tell real ...


3

Can't we do something about it? Can we as a community blacklist the thief's account? I can't find the link at the moment, but there was an e-wallet service that was robbed, and Mt.Gox requires you to submit identity documents if you want to sell bitcoins derived from that robbery. Or put out an "all-points-bulletin" to flag transactions using the thief's ...


3

It is unlikely you'ld find an exchange that hasn't lost funds due to theft. Mt. Gox, before Tibanne bought it, used to accept PayPal for payment. It was fraudulent PayPal transactions that assisted in driving the exchange rate from $0.06 per BTC (yes, that is correct) in October, 2010 to a level twice that in about two days. PayPal closed the account and ...


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