Relates to attempts to harm the Bitcoin network. In cryptography, an attack is a method/technique to break the code. Bitcoin also has to deal with other types of attack, such as double spends and denial of service.
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Government disrupting reception of bitcoins. Is it possible?
I was thinking of a very specific scenario: Suppose we have a new organization, let's call it "WikiLeaks2", which receives donnations mostly in the form of Bitcoins. Suppose a national government ...
7
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3answers
351 views
Why do pools get so often DDoS attacked?
In other words: who has incentives for attacking pools?
Do you think it's the government?
6
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1answer
355 views
What is the Ripple equivalent of the “51% attack?”
In Bitcoin, if a participant gains control of more than 50% of the hash power, they can execute a double-spending attack. The "attack" could come from within, say if the existing powerful miners ...
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0answers
19 views
Could the target become unreachable? [duplicate]
As far as I understand it, the target T is a floating point number that is adjusted based on the moving average of the difficulty of some previous transactions. Mining a block happens when somebody is ...
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2answers
99 views
How long does it take to go from 51% hash power to 100% hash power?
Once an attacker has acquired 51% hash power, is it possible to quickly get to 100% hash power by simply refusing to build on blocks created by other mining nodes and therefore discouraging mining ...
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1answer
274 views
DDoS on big mining pools: a quick way to 51%?
Slush's Pool, the second biggest mining pool around, is currently down, allegedly due to a DDoS attack:
News
16.04.2013
Pool is under DDoS attack. I'm working on recovering the service back to ...
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1answer
156 views
Can someone saturate the network?
Suppose I have 2 wallets and 1 bitcoin and I write a program to make transfers of 1 satoshi from one wallet into the other.
No suppose I have 100 bitcoins. Wouldn't that saturate the network?
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1answer
87 views
Feasibility of a “High horsepower” attack (based on difficulty -4x adjustments)
This is really Part 3 of this earlier question.
Given that the QT client is hard coded to never adjust difficulty more (or less than) a factor of 4...
What realistic scenario would cause the ...
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1answer
25 views
What's the impact of net-splits on block generation… over a long period of time?
Part 1
For this question, assume the overall hashrate of the environment is constant.
If 25% of the network hashpower were to be isolated (Australia had no Internet for example), what is the effect ...
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2answers
246 views
Developments to prevent 51% hack [duplicate]
How might Bitcoin be made impervious from attack by large monied interests that could atttack with a brute force majority hashrate hack?
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1answer
293 views
Can a Finney Attack make SatoshiDice betting profitable? [duplicate]
Can a Finney Attack make SatoshiDice betting profitable? If you perform a Finney Attack whenever your bet fails (by replacing it with a transaction to yourself), then would it make betting profitable, ...
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1answer
85 views
Possible to include a per miner transaction to prevent withholding and independent rebroadcast of a solved block?
Update: This is a bad idea because it simply won't work, but it did help me understand what happens between a Miner and a Pool.
And if you missed it in the comments, read @Meni's PDF for a threat and ...
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1answer
523 views
Could a mining pool attack Satoshi Dice?
Is it possibile for a mining pool to attack Satoshi Dice? A strategy might be: bet on Satoshi Dice and if the bet wins, do nothing, if it looses, don't put the transaction in the block (try to double ...
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3answers
502 views
Is the minimum amount of money required to purchase >50% hash power equal to max worth of all existing bitcoins?
20 BFL Bitforce Mini Rigs (each, $30k) will give about 30THash/Sec hash power for $600k. That's way above 60% of hash power of then total 51THash/Sec.
10.694M total Bitcoin * $18.5 current mtgox best ...
4
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1answer
62 views
I'm developing on the Test network. Are there any “rules” or communication methods I should adopt?
I'm testing a C# port of the client on the Test network and need to test for a variety of conditions.
Should I communicate to others regarding my actions on the network? If so, what method of ...
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2answers
115 views
What stops miners/nodes lying about what time a block was mined?
From what I understand, the difficulty required by the proof-of-work in bitcoin is a function of block history, specifically the average time between last ~2000 blocks, with the intention that its ...
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2answers
437 views
How much would it cost for a government to undermine Bitcoins?
Articles by for example the Economist stating that Bitcoins are being used for drug trading (Silk Road), I believe that the biggest risk to Bitcoins is that a government will pull a stunt similar to ...
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2answers
262 views
What is a double spend?
What is a double spend?
As someone who uses Bitcoin, what do I need to know about how the Bitcoin system prevents double spends? Are there still circumstances where they can occur?
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1answer
150 views
How do mining pool payout methods affect the cost of executing a block withholding attack?
I'm wondering how each payout method (PPS, DGM, PPLNS, Proportional, etc) influences the cost of executing a block withholding attack.
Does it matter how the payout method places variance between ...
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2answers
363 views
What is a block withholding attack?
How can a block withholding attack be performed, what would be its purpose and who is it a danger to?
Edit: when I posted this I was thinking about withholding a block you mined in a pool. But ...
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2answers
404 views
What is a Finney attack?
What is a Finney attack? Extra points for explaining its purpose, the prerequisites for it to be possible, how the attack can be performed and the origin of the name "Finney attack".
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3answers
210 views
How can I assure my consumers they are actually paying the correct person? (prevent MITM attacks)
There are many network level attacks that give someone Man in the Middle ability to replace my Bitcoin address with their own.
Since there is no way to cancel a transaction, and the best practice ...
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2answers
380 views
How can I find well-connected nodes?
If I am a merchant accepting 0-confirmation transactions I should protect myself against race attacks. Several resources state that I should configure bitcoin daemon to not listen for incoming ...
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3answers
311 views
Does the protocol ensures that private keys are unique?
There is a very very low chance for the same private key to be generated. (source)
However, what happens when my generated private key matches a private key that is already used?
Does the protocol ...
6
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3answers
213 views
What nodes are best for lessening the risk of loss from a race attack
A successful race attack is one where the payment recipient's node receives a spend transaction yet the next block that is mined has a different transaction that spends the same coin. Thus the ...
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1answer
372 views
What does a double spend look like?
What does a double spend look like? Can anyone link to an example on blockchain.info?
Will invalid half of the double spend simply remain at 0-confirmations, or might it ever reach 1 or 2? Will the ...
2
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1answer
275 views
What user data has been leaked from MtGox's database during June 2011 hack?
What user data has been leaked from MtGox's database during the June 2011 hack? Is the database still available for download anywhere, like it was almost a year ago?
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1answer
593 views
What is the story behind the “Linode problem”?
What is the story behind the "Linode problem"? How did the service become compromised and what has exactly happened because of it?
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1answer
269 views
Does any pool accept higher-fee transactions of a double spend, instead of the earlier one?
Some pools use a modified bitcoind that uses different rules for choosing the transactions to include in a block. Are there any pools that knowing one transaction to be included in a block would ...
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0answers
78 views
What are the most notable attacks on pools?
Over the course of the Bitcoin history there were a couple attacks on the pools. There was the Linode problem, some people got their coins stolen from their pool's accounts and so forth. What were the ...
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1answer
125 views
Do the DNS servers make Bitcoin more secure than the IRC channel? [duplicate]
Possible Duplicate:
How secure are the DNS servers for Bitcoin?
In earlier version of Bitcoin the IRC channel was used to seed initial peers, and as of version 0.6 it was largely replaced ...
5
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1answer
310 views
How secure are the DNS servers for Bitcoin?
With the version 0.6, Bitcoin introduced the DNS servers that populate the initial peers for new clients. How secure are those servers in terms of being immune to takedown attacks, or injection of ...
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1answer
355 views
What is the story behind MyBitcoin?
The name of MyBitcoin eWallet comes up quite often here and there. What is the story behind it and the attack on it they claimed occurred?
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0answers
254 views
Was a timejacking attack ever performed?
The timejacking attack appears to be a pretty straightforward attack to pull off successfully. I was wondering, whether it was ever performed and documented somewhere, or was it just theoretically ...
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1answer
105 views
Is an attack on a local bitcoind via an img or embedded flash viable?
In this thread on the Bitcoin forums it was suggested that a local attack on bitcoind might be possible through malformed img tags or (more likely in my opinion) through embedded flash. This also ...
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1answer
364 views
What is the story behind the attack on Coiledcoin?
A couple months ago I came across the news about Eligius pool being used to destroy an AltCoin called Coiledcoin. As I understand the miners of the pool did not know their hashing power was used in ...
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3answers
678 views
What can be done about the no-transaction block relayer (currently 71.123.170.150)?
An unknown major solo miner (currently IP 71.123.170.150), most likely a botnet, is relaying blocks with zero transactions. Two weeks ago this miner constituted ~15% of the network, now it constitutes ...
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3answers
453 views
Are big miners a threat for Bitcoin?
According to this graph, the biggest miner is so big that combined with two of the three runners-up they would have more than 50% of the hashing power.
Is that to be considered a threat to the ...
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1answer
315 views
Which blocks get to be checkpoints?
Which blocks get to be checkpoints, and why is one block chosen to be a checkpoint, rather than another block? And where can I find a list of checkpoint blocks?
2
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2answers
250 views
How would one inject a blockchain fork to the Bitcoin network?
For theoretical purposes, how would one inject a blockchain fork in to the Bitcoin network? For example, lets say we have a small chain of blocks prepared in a program that is not a standard client / ...
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2answers
227 views
Why would you need to “catch up” in the 51% attack?
There is a lot of information on the 51% attack where an attacker is able to branch the chain and "catch up" and build a new branch that is longer than the old branch. Other than requiring more than ...
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2answers
106 views
Current block vs whole block chain attack
If an evil computer network wanted to attack Bitcoin, would they need to have more computing power than the present Bitcoin network and then attack a current block, or would they need even more to go ...
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3answers
2k views
What are the risks of using Strongcoin.com as an online wallet?
Strongcoin claims it is "The Safest way to store your Bitcoins. The only Bitcoin e-wallet service that's not vulnerable to security breaches. Your Bitcoin keys are encrypted in the browser."
As I ...
7
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3answers
443 views
Flaw in Bitcoin protocol regarding incentives to share transactions
Once the 50BTC per block rewards have halved many times and the transaction fees start to become the primary reward for miners, it sound like there is incentive for miners to not pass on transactions ...
7
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4answers
351 views
Would any of the current botnets be able to launch and sustain a 51% attack?
The "owners" of botnets probably runs them as businesses, meaning that they will always seek profit-optimization. Do you believe that it is a matter of time before they will seek to launch and sustain ...
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2answers
269 views
How to perform a double spend attack in websites that accept transactions with 0 confirmations?
To perform a Finney attack or a 51% attack I need to have lots of computational power, but in this case (a website that accepts transactions with 0 confirmations) it seems to me that I only need to ...
5
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4answers
184 views
Do no-fee transaction represent a greater risk if the product is delivered instantly?
Let's say I want to accept payments instantly on a site for digital downloads.
So I publish an address and wait for the unconfirmed transaction, I see the transaction and release the digital ...
5
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1answer
70 views
What is the maximum number of signature check operations a transaction script can request?
As transaction size, the number of signature checks per transaction can affect client performance and the inclusion of many O_CHECKSIG opcodes could be used as a tool for denial-of-service attacks.
I ...
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1answer
362 views
What is the maximum size of a transaction?
I see from the source code (script.cpp) that there is an upper limit in the script size. It there any other limit to avoid a single transaction preventing other transactions of smaller sizes to get ...
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1answer
341 views
What are checkpoints?
I often read that checkpoints protect the network from a 51% attack because an attacker cannot reverse transactions made before the last checkpoint.
How exactly does this checkpoint mechanism work? ...
