Questions tagged [security]

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

114
votes
11answers
57k 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 ...
26
votes
5answers
2k views

How much would it cost to execute a 51% attack?

I know that it's commonly said that they're not really in the realm of possibility right now, but how much would it really cost to execute a 51% attack on the network? And are there any organizations ...
2
votes
1answer
390 views

How to verify the Bitcoin core software?

I just installed Bitcoin core (v0.15.1) for the first time. I've read that it's best to verify the software after downloading, but I don't see the links that are referred to in the instructions/videos....
1
vote
2answers
127 views

Eliminating all private keys records from pc

Suppose I buy a new wifi router and a new pc. I set up both the wifi network (of course, with a password) and the pc. Now I access the internet for a few seconds in order to download bitaddress.org ...
6
votes
1answer
547 views

If a single private key of the HD bitcoin account is compromised, is the whole HD account compromised?

The subject pretty much asks it all. I asked the same question on the Mycelium web site but did not get an answer. An HD account can have multiple private keys. Suppose one of the previous private ...
2
votes
0answers
407 views

Safely generating Bitcoin paper wallets [closed]

I'm new to Bitcoin and I have recently purchased a few fractions of Bitcoin. My BTC are stored on what I understand is an online wallet (a website where I log in using two-factor authentication and ...
3
votes
2answers
55 views

Querying UTXOs with random key pairs

As the number of transactions in the bitcoin network grows, the number of addresses with bitcoin will also grow. Is it possible for someone to “scavenge” for bitcoin by generating random key pairs and ...
0
votes
3answers
314 views

What happens if everyone discovers much faster way of solving hash function problem (mining)?

The question is not about how bitcoin mining works, but rather how bitcoin system adapts to progress in ability to tackle proof-of-work problems. Suppose that proof-of-work problems used for bitcoin ...
1
vote
1answer
110 views

Can a Bitcoin ( or any other cryptocurrency ) be compromised with a large botnet/s?

I'm new to cryptocurrencies, so I recently read the paper from the Satoshi Nakamoto ( link is here ) to know a little bit more about the Bitcoin.And I saw this statement: What is needed is an ...
6
votes
3answers
2k views

Which exchanges support U2F authentication? [closed]

I got myself a nice security key (Yubico Fido) today, which utilises the U2F protocol. But to my surprise not a single Bitcoin exchange seems to support this yet, only Google itself. So which ...
1
vote
1answer
666 views

Security risk(s) in running bitcoin core full node

What are the security risks posed by running a full node bitcoin core client? On a typical system, port 8333 is open and all other nodes can actually 'see' my machine and sites like https://bitnodes....
4
votes
2answers
230 views

Security implications of regular saving into cold storage

I am thinking about following this plan: Regularly buy bitcoins in an online exchange, 100€/month at market prices. Once the balance in the exchange exceeds a certain limit (500€), move those ...
3
votes
1answer
61 views

Is it better to compile bitcoin node or rather for some reason just use the official binaries?

As I have some doubts about a possible hackers' attacks on https://bitcoin.org/ Wanting to run a full node, I rather compiled the Bitcoin Core from git source for Linux instead. The question is: ...
0
votes
1answer
226 views

How to generate a paper wallet?

What do you find the best way to generate a paper wallet for BTC? I've heard of this one: https://keybase.io/warp/warp_1.0.9_SHA256_a2067491ab582bde779f4505055807c2479354633a2216b22cf1e92d1a6e4a87....
2
votes
2answers
527 views

Why is it safer to keep your bitcoins offline than online on Coinbase?

I'm trying to think of a good way to store my bitcoins somewhere but I can't really think of a way to do it without 1) having something physical (eg. USB key) that can get lost or destroyed 2) having ...
4
votes
3answers
1k views

How to make PoS system work?

In a r/bitcoin I've found the following statement: I think it should be noted that this paper covers a "pure" PoS system, but there have been some hacks to PoS systems to make them "work" (work ...
4
votes
0answers
109 views

Zcash proposal to use checkpoints to verify monetary supply [closed]

Based on concerns about the trusted setup not being able to conclusively disprove the ability to create hidden inflation, Zooko recently described an idea to institute checkpoints to verify the total ...
8
votes
3answers
47k views

Is it safe to store all my coins on Coinbase?

Is it safe to store my coins (BTC & ETH) on the Coinbase platform or is it safer to download a wallet to keep them in?
1
vote
4answers
1k views

Trezor Custom Mnemonic

How do I go about using words I pick in a trezor seed? I only want words that I select and in an order I select. I'm not worried about this being a less secure way to generate a seed. I will be doing ...
2
votes
3answers
650 views

Any need for coinbase field in coinbase transaction?

My understanding is that every block in the bitcoin blockchain has a coinbase transaction which contains a coinbase field. It is essentially an orphan field (placeholder) for use in claiming existing ...
2
votes
1answer
742 views

How to open new wallet into Bitcoin Core and switch between?

I have my old wallet which private key is compromised. So my reasonable way is to open new wallet and move all bitcoins from compromised wallet to new wallet. I use Bitcoin Core. I do not trust any ...
31
votes
2answers
13k 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".
3
votes
4answers
703 views

Would bitcoin be destroyed if a wealthy organization obtained a CPU majority for a sustained period?

Inspired by this question ("Could bitcoin be destroyed by an entity cornering the market?") and the top comment on this answer to this question ("How much would it cost to execute a 51% attack?"). ...
2
votes
4answers
144 views

What can an attacker who controls majority or all of the full nodes do?

What happens when a strong attacker has control of majority or all of the full nodes? What damage can he do and would they be reversible?
0
votes
1answer
365 views

What is crypto-proof UTXO set?

There are many opinions about getting the actual UTXO set of blockchain. Do you think that this important database must be based on data which saved on disk and never modified after, only appended? ...
43
votes
4answers
15k views

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 ...
0
votes
2answers
7k views

GUI miner not working properly (slush's pool)

I'm trying to mine for slush's pool with GUIminer. The miner says that I am mining, and gives me a mhash number, but says that no matter how long I mine, I still have 0 shares. The pool says that I ...
2
votes
1answer
53 views

How to keep my bitcoin safe when I move my bcash?

I had some bitcoin during the coinsplit, so now I have bcash that I want to move. When I send bcash there is a risk that someone copies the transactions and uses it to steal my bitcoin. Most people ...
10
votes
2answers
2k 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
votes
2answers
143 views

Segwit2x/btc1 block header changes: wipeout protection for SPV nodes?

Are there any current plans for segwit2x/btc1 to change the block header in a backward-incompatible way, either permanently or with a signal block (e.g., "hard fork bit"), before it goes live? This is ...
1
vote
0answers
369 views

Can a private key enumeration attack be used to steal bitcoins? [duplicate]

Let's consider the following algorithm enumerate all of the private keys for each of the enumerated private keys, generate the relative public key and verify whether there is any unspent coin ...
7
votes
2answers
1k views

Has someone compared the cost of mining vs. that of brute-forcing addresses?

It is known that the type of computing power required for mining is the same used to generate addresses, and it is known that "in general" it is much more profitable to simply mine, rather than try to ...
2
votes
3answers
2k views

If someone knows my bitcoin address, does this mean they can spend it or move it?

What if I wrote down or saved a file with the address on and someone found it, can they take my coins? How secure is it?
0
votes
1answer
98 views

method to keep private key in the open?

say I have this private key: 5HpHagT65TZzG1PH3CSu63k8DbpvD8s5ip4nEB3kEsreAnchuDf Now let's say I take the 5 out then take any location of this string and flip it: bpvD8s5ip4nEB3kEsreAnchuDf ...
3
votes
2answers
856 views

The shortest ECDSA signature

I want to create ECDSA signature {r,s} where r is very low (for example 1) and can be encoded in DER-format in one byte. How to calculate k value? Seems to me that it does not depend of anything. ...
0
votes
1answer
56 views

about a stuck bitcoin transaction

I sent 24mbtc over a week ago with the transaction number abef483d268dc61214fd5bf25c602256cf447aa65bec2e539fee42f59a3b90b3 the person i sent to still says, they have not received anything yet the ...
3
votes
3answers
159 views

Securely encrypting a cold storage wallet

I'm going to buy bitcoin to exchange BRL to CAD currency, as it's gonna be a great amount I'm concerned about the security of my wallet. I don't want to use a physical backup like paper or device ...
1
vote
0answers
128 views

why a website for buying bitcoins is asking for my CVC code [closed]

I am trying to create an account on coinbase to buy bitcoins (in france). But coinbase is asking for my cvc number while creating the account, not for a purchase. I am afraid for security issues, as I ...
1
vote
1answer
103 views

Sensitive information stored in contracts

Is it a good idea to store some sensitive data on the blockchain contracts? For instance, i want to make a contract that stores vouchers (that cost real $$) and once the user pays to the contract for ...
0
votes
1answer
290 views

Why is using a simple SHA1 in a scriptPubKey to emulate a “password” a security problem?

I'm independently working my way through an excellent online course on bitcoin, made available from Stanford. (https://crypto.stanford.edu/cs251). One of the problems in the homework challenges the ...
16
votes
7answers
2k views

What is the safest medium on which to store my wallet/private keys?

What is the safest medium on which to store my wallet/private keys? I avoid eWallets like the plague. I have my wallet on my computer at the moment with the Bitcoin passphrase encryption and I have ...
0
votes
1answer
175 views

Is there an alternative to Bloom filters?

There have been a few papers, online publications and discussion about the negative effects of bloom filters on privacy. What are the alternative to using bloom filters? (bonus question: Are there ...
2
votes
2answers
462 views

Having an address without a wallet

If somehow I have an address with its corresponding private key but I have no wallet (well maybe I use some wallet to generate the address/key and then throw it), would it make sense to collect coins ...
55
votes
8answers
38k views

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'...
54
votes
7answers
43k 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 ...
0
votes
1answer
105 views

Can spent transactions that get pruned lead to false payment claims?

The bitcoin white paper says that spent transactions get pruned after being buried behind enough blocks: Reclaiming Disk Space Once the latest transaction in a coin is buried under enough ...
1
vote
1answer
253 views

How can trading phisical goods in the blockchain be safe?

Suppose we have two people: a merchant (Bob) and a buyer (Alice). Alice wants to buy an expensive good from Bob in excange of bitcoins, so she contacts him and sends him the amount of bitcoin needed. ...
10
votes
2answers
7k views

The length of the Bitcoin's private keys

I read here: In Bitcoin, a private key is usually a 256-bit number ... Although it is a silly question, is this length safe? Based on this site, Elliptic Curve 256 bit keys are safe until 2040. ...
0
votes
1answer
379 views

Bitcoin's disappeared from unused wallet

wondering if I could get some help from you experts on something that has been bugging me for a bit. I found an old bitcoin wallet I had forgotten about. You can see its information here. I was ...
1
vote
1answer
228 views

If the PHP script and the Bitcoin wallet are on the same computer, does encrypting the link is necessary?

Dears, If the PHP script and the Bitcoin wallet are on the same computer, does encrypting the link is necessary? like turn ssl on:rpcssl=1