Security issues with the design or implementation of Bitcoin.
Security in Bitcoin encompasses many topics. These include wallet encryption, ECDSA, signing and encryption algorithms used elsewhere, etc.
Questions tagged [security]
923 questions
149
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8 answers
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?
ripper234
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140
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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 profitable) for someone to find collisions in the bitcoin…
nmat
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122
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5 answers
Why is 6 the number of confirms that is considered secure?
Why is 6 is the number of confirmations that is considered secure? I haven't found any mathematical explanation or otherwise that explains why it is 6 and not 5 or 7. Is there a historical reason for 6? Is there a specific way to calculate it so 6…
osmosis
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60
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4 answers
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 prevent other people winning their 50 BTC and…
billpg
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58
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8 answers
What effects would a scalable Quantum Computer have on Bitcoin?
A scalable quantum computer is a quantum computer that is easy to extend - adding more (q)bits of memory is not a fundamentally hard problem, and will happen. Or, alternatively, that it follows Moore's Law - its memory capacity and speed will…
ripper234
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57
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4 answers
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 cryptography pieces. Have any well-regarded cryptography…
lemonginger
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57
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10 answers
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 precondition that they were able to scare away all the…
David
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57
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7 answers
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 copy them. Does this mean that bitcoins can be…
eMansipater
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53
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Why was the target block time chosen to be 10 minutes?
According to the wiki, 10 minutes was chosen as a 'tradeoff'.
Why ten minutes specifically? It is a tradeoff chosen by Satoshi between propagation time of new blocks in large networks and the amount of work wasted due to chain splits.
However in…
z7sg Ѫ
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46
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8 answers
How long would it take a large computer to crack a private key?
I am doing a presentation on Bitcoins and I was looking for some calculations to make people feel safe about the private key encryption. Please first answer, how long in bytes the private key is, then how many combinations of numbers it will…
shoeless joe
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44
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10 answers
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 wallet file then I lose access to those coins. …
Michael McGowan
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40
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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".
Dr.Haribo
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40
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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 to issue the payment
The seller must have a way…
nmat
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39
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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?
Gary
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39
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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? And who creates the checkpoints?
nmat
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