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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.

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1answer
132 views

What would happen if every miner adds a transaction to his block that did not occur?

Let's say every single miner in the world added the same transaction to their block via trickery. The transaction was never initiated by the wallet holder. Would a block from these miners be added to ...
3
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1answer
340 views

How is a stratum connection secured?

Does stratum mining use something similar to "https" to secure traffic between the pool and the miners?
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2answers
114 views

What are the implications of a huge amount of unused hash power?

A not unthinkable scenario is that the Bitcoin price decreases to, say, 10-20% of today's value. This would make mining less profitable, and the difficulty should adapt accordingly. This should lead ...
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2answers
272 views

Why don't the miners just take profit from our coins and make the coin worthless?

You own a very valuable thing and you want to go to holiday without it, but there is nobody who you trust and who can look after the thing. So you take somebody unknown to guard it. You pay him a fee ...
2
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1answer
292 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....
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1answer
266 views

A theoretical low cost attack scenario in PoW currencies

The scenario was designed by user:croraf and me in discussing a question of mine yesterday. To make it more clear, I want to present it here again in a stricter design. To do it in a clear way, first ...
4
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3answers
343 views

Egoistic miners combined with large transactions destroy PoW?

EDIT There is a clearer description of some parts of the problem in the link questions. If there is a transaction value much higher than the payment for mining 10 new blocks, how can you trust this ...
1
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2answers
118 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 ...
7
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1answer
495 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
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0answers
377 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 ...
1
vote
1answer
168 views

Who decides what the next, correct Nonce is?

As I understand finding the correct Nonce is the basis when hashing transactions for Proof of Work. How and where is this decided in the ecosystem what the next Nonce is? In my limited understanding ...
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3answers
283 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
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1answer
104 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 ...
1
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1answer
590 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
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2answers
219 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
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1answer
60 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: ...
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2answers
107 views

Does my Electrum wallet become less secure if I keep generating seeds until I see one I like the look of?

Let's say I want to create a new electrum seed... I didn't like the initial seed words, since I want to remember them and these didn't look too appealing. Looking "too random" for my taste. When I ...
0
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1answer
199 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
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2answers
482 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 ...
3
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2answers
52 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 ...
6
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5answers
3k views

How to make totally secure Bitcoin transactions?

So, I'm wondering if my system of protecting my bitcoin is totally secure. If I have an old laptop, and I boot into tails linux from a flash drive, and download electrum on there, and only ever ...
1
vote
1answer
54 views

What prevents a node from sending a different version of the blockchain?

I understand that proof of work prevents a node from creating a new version of the blockchain unless they have >50% of the hash rate, but what if the attacker is also able to intercept the victim's ...
1
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3answers
359 views

How safe is it to use online wallets? [closed]

I want to know if it is safe to use online wallets? Can we trust online storages which stores our privkeys, passphase and wallet.dat files? I read that at least one android wallet was hacked so I ...
2
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1answer
639 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 ...
2
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4answers
134 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
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1answer
355 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? ...
2
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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 ...
2
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2answers
142 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 ...
4
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3answers
2k views

How is the lightning network secured against hacking and double spends?

As I understand payment-channels, like the lightning network, they are working off chain (no record in the blockchain). The only record to the blockchain is the deposit transaction to open the payment-...
1
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0answers
351 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 ...
0
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1answer
87 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
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4answers
334 views

Store Bitcoins offline

I have some bitcoins and ether at Blockchain.info and I am really scared of losing them. How do I best secure them? Right now I have a paper with the code to restore my wallet, but my coins are still ...
0
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1answer
55 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 ...
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0answers
122 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 ...
2
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3answers
1k 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?
1
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1answer
102 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
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1answer
174 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 ...
0
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1answer
164 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
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2answers
402 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 ...
0
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1answer
96 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
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1answer
237 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. ...
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3answers
498 views

Is creating a long password for my coinbase account enough to keep my bitcoins secure?

I've made an account with coinbase and purchased some bitcoin. Only after to start reading people talk about getting hacked and how bitcoins are not secure unless you put them in a "wallet".To be ...
1
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1answer
331 views

What would happen if a mining pool admins having majority of hash power turns evil?

This question interest me mostly in the context of the Ethereum, but it might be interesting to see how this problem is solved by the other cryptos as well. I understand that the consensus about what ...
0
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1answer
105 views

How would one go about acquiring the HashofThingtoSign from this old transaction?

How would one go about acquiring the HashofThingToSign that is used in the "Signature Generation" equation for this example transaction such that it could easily also be applied to any other given pre-...
1
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1answer
214 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
-1
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1answer
758 views

Could miners possibly steal SegWit transactions on The Real Bitcoin? [closed]

Going to be lolz epic when all the SegWit transactions are double-spent, i.e. stolen by miners on The Real Bitcoin (the legacy Satoshi blockchain). Can anyone offer any refutation, confirmation, or ...
1
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2answers
426 views

How to securely store Bitcoin server-side?

I am working on a web application that needs to hold users Bitcoin for an extended amount of time (escrow-like scenario), and I was wondering what are some good steps/precautions and principles (dos &...
2
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0answers
43 views

If you had the resources of a Nation-State, could you invalidate Bitcoin chain? [duplicate]

Scenario: The financial 1% feel threatened by bitcoin. The United States Federal Reserve convinces the senate that bitcoins utility for terrorism and untraceable payments and will cause tremendous ...
0
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2answers
168 views

To what degree can Bitcoins on a hard disk be protected against hacking?

This is a question that came to my mind after reading this other question from someone who had "found a heap of BTC" on a hard drive. In that persons case they had originally been purchased many years ...
0
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1answer
101 views

Does ad hoc adoption of private blockchains make the financial system vulnerable to tampering?

The security of a blockchain network depends on how many nodes are participating in that network. More number of participating nodes, implies better security. Currently, many financial institutions ...