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Questions tagged [security]

This tag should be used for questions regarding security issues with the design or implementation of Bitcoin and related cryptocurrencies.

4
votes
2answers
630 views

How many consumer computers would it take to launch a 51% attack [closed]

What is the hash rate of a standard laptop using the default client and what is it for the whole of Bitcoin? I am interested in this, because I want to understand what it would take to get to 51% of ...
15
votes
1answer
2k views

What is the “zeitgeist attack”? Does it affect all blockchain technologies?

What exactly is this attack? It would be nice to have a good explanation of how it works and which chains can be effected by this. Does it apply to the bitcoin main chain, or only the newer and ...
16
votes
5answers
2k views

What can xxxCoin do to stop the impending 51% attack?

Within the coming weeks both Namecoin and SolidCoin have been threatened with the same attack. What can be done by the users, pool operators and developers of these forks to either; A. Minimise ...
9
votes
2answers
1k views

Why did BitcoinEXpress plan a 51% attack on Namecoin?

I don't understand this post. What is "ArtForz modified exploit"? What does "Gavin's patch will not work for the exchanges" mean? Any more important details I'm missing?
18
votes
2answers
3k views

How does a client decide which is the longest block chain if there is a fork?

Is it only the block height or is it the effort that went into the forks? In other words: does this decision account for different difficulties?
50
votes
4answers
29k views

What keeps the average block time at 10 minutes?

I've been told "the network" sets the difficulty level such that there will be one new block mined every ten minutes. I imagine the rich would instead prefer to keep difficulty as high as possible to ...
5
votes
2answers
396 views

What incentive is there for a miner to not include a bad transaction?

'A' has got 1BTC legitimately. He sends out a transaction to transfer that one bitcoin to 'B' with a 1BTC transaction fee added on. (i.e. a bad request.) 'C' is a miner who cares nothing for ...
9
votes
2answers
442 views

What prevents bitcoin from breaking down in case of a “transaction attack”

Let's say that I want to kill Bitcoin by means of a transaction attack. What in the bitcoin system prevents the following approach: I buy a limited number of bitcoin in the market. Using a small ...
8
votes
1answer
1k views

What is BlitCoin?

I saw BlitCoin mentioned on this forum thread, but didn't understand what it was. Can someone explain what does it do?
35
votes
5answers
6k views

What is a deterministic wallet?

It sounds as if it's a process that enables a wallet to be rebuilt from a passphrase, or from several fragments scattered about. Could someone provide a detailed technical explanation?
128
votes
8answers
46k views

What can an attacker with 51% of hash power do?

Suppose organization X has 51% of the hash power for a period of 1 week. In this week, what exactly can and can't X do?
6
votes
1answer
353 views

What is meant by “releasing code tells the hackers what to attack”?

I came across this statement from a SolidCoin developer: Can anyone explain this statement? [06:48] gavinandresen: I came here to ask RealSolid to be responsible and report problems or ...
28
votes
7answers
3k views

How can one download the bitcoin client securely?

What is the correct procedure to download the official bitcoin client, and validate it was signed by the developers, and not infected with any malware by a man in the middle?
12
votes
1answer
264 views

What security features are built in to the standard Bitcoin software?

I have read much of the Bitcoin algorithm and its encryption basis, however little has been said of the software's inherent security. What solutions are already built in to the software, and what is ...
25
votes
8answers
3k views

How can a single person operation keep a collection of online wallets secure?

While this question is similar to others about securing wallets, I think it merits a question of it's own. One thing that has dissuaded me in the past from running an online wallet service of some ...
13
votes
2answers
341 views

What are the minimum security expectations of an online wallet service?

If you wanted to assess the security of an online wallet service such as a bitcoin bank or ewallet, what would expect to see addressed? Obviously SSL connections, but what about authentication, ...
19
votes
1answer
2k views

What protection does Bitcoin have against Denial of Service (DoS) attacks?

What protection does Bitcoin have against DoS attacks? Could you bring down a node by flooding it with data? What happens if someone starts flooding the network with legitimate, yet nonsense, ...
21
votes
4answers
1k views

Are there any fundamental security vulnerabilities in Bitcoin?

Although Bitcoin does its best to prevent double-spending, could it still happen in practice? Is it just very unlikely that fraud could happen, or is there a mathematical proof that it could never ...
9
votes
2answers
236 views

Do any of the Bitcoin exchanges implement trading curbs?

After the big hack of Mt Gox we all became aware that there is nothing in place to prevent "flash crashes." Most stock, FOREX and other exchanges have features like trading curbs or other market ...
54
votes
4answers
6k views

Have any cryptography experts vetted the bitcoin source code?

Theoretically, bitcoin's open source nature makes it more resistant to bugs and exploits. However, due to the specialized nature of the code, even many programmers don't fully understand the ...
47
votes
9answers
5k views

What methods could a government use to shutdown Bitcoin?

Let's say that a government decided to shut down the Bitcoin network. What options would they have to achieve this? Would they need to convince other governments? All governments? Let's set as a ...
6
votes
2answers
256 views

Is the authentication system of the Bitcoin <-> SMS service PHONECO.IN adequate?

@osmosis made me aware of PHONECO.IN, which makes it possible to send Bitcoins via SMS. My question is whether their authentication system is adequate. From their website: PhoneCo.in is designed to ...
20
votes
6answers
2k views

How can I send Bitcoins via SMS?

I am considering working on giving Africans access to trade using Bitcoins. In many ways, parts of Africa is more developed when it comes to mobile payments than the west. The success of M-PESA ...
36
votes
5answers
2k views

How do I accept bitcoin payments at a real world store?

From what I understand, there are some requirements for using bitcoins at a physical store: Both the store owner and the client must have Internet access The client must have a cellphone or a laptop ...
32
votes
1answer
51k views

How can I restore my wallet?

I just purchased a new laptop and I want to decommission my old one. I have a back-up of my wallet.dat file copied to my new PC. What do I need to do to restore it to my Bitcoin (Windows) client? ...
31
votes
2answers
2k views

Do mining pools centralize the Bitcoin network and make it less secure?

A mining pool with a significant percentage of the hash rate could allow double spend attacks by the pool manager. There are a number of pools that approach this level. However, most people say that a ...
12
votes
3answers
1k views

Do wallet stealing viruses exist?

After I install the bitcoin client, what are the risks of browsing the Internet? Can my wallet be stolen? Are there any known viruses/websites etc....?
53
votes
7answers
41k views

Can bitcoins be counterfeited?

Traditional currencies have anti-counterfeiting features designed to make them hard to copy, but despite this attempt counterfeit money is a real threat. Since bitcoins are digital, it's trivial to ...
16
votes
5answers
2k views

Is Bitcoin future-proof?

As I understand things, the security and integrity of Bitcoin rely on the assumption that its hashing is "hard" in some sense. However, in the past, processing power has increased exponentially. ...
44
votes
9answers
8k views

How can I keep my wallet secure?

The standard Bitcoin client does not encrypt wallet files, so any malicious user that gains access to this file will be able to transfer all the coins to their own wallet. Furthermore, if I lose the ...
112
votes
11answers
53k views

Is it possible to brute force bitcoin address creation in order to steal money?

Bitcoin users frequently generate new addresses for each transaction they make, which greatly increases the number of bitcoin addresses being used to receive money. Would it be possible (and ...