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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28 views

What kind of bug does bitcoin core possess that have to be replicated

In order to build a bitcoin client accepted by the current bitcoin nodes we to have to emulate the C++ code present in the bitcoin core client, with all its attributes even the bugs. For example the ...
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2answers
29 views

Can I see the address of my direct peer?

Can I see the bitcoin address (pkh) of my directly connected peers? I'm asking this question because if I can, I can deanonymize my peers given their IP addresses (from the TCP header) right? If ...
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Can a 'free' Bitcoin 'marketing' ad be checked in any way

Total Bitcoin newbie here. I have no bitc, nor a wallet, nor am I sure I want one. I've been intrigued for a while, but security is a big passion of mine... Today just now youtube pointed me to an ...
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26 views

How do bitcoin nodes agree who first mined ablock?

Once transactions are broadcast and a node starts working on a proof of work, and finds it, it broadcasts it to all other nodes for that block to be verified and added onto their blockchain. All nodes ...
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1answer
36 views

How can you trust Bitcoin nodes?

If you send send a transaction request to a node, what is to to ensure that node doesn't simply log your private key and do nothing? What is to stop the entry node from taking a transaction intended ...
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1answer
64 views

Downloading the pruned blockchain file directly from external source

Using the bitcoin client to have a pruned version of the blockchain can take a lot of time, I was wondering what would be the drawback to simply download an already pruned bitcoin blockchain file from ...
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1answer
101 views

My Bitcoin Core Sent Bitcoins Without My Authorisation

I am running Bitcoin Core version v0.19.0.1 (64-bit) on Windows 7, and on 27 February I noticed that it sent 0.0045 bitcoins on its own. The wallet is encrypted at all times and I enter the ...
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1answer
53 views

Relationship of Bitcoin address and Public Key

I am trying to understand relationship between your Public Key and bitcoin address. After reading few blogs my understanding was that after generating your Master Key pair, in HD wallet. One should ...
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2answers
46 views

What prevents a knowledgeable person from modifying their bitcoin data?

The average person would not have the knowledge, but what is the mechanism that stops a programmer capable of writing a wallet, from modifying the local bitcoin file/data to be, for example, 10 ...
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36 views

similar seed words minor sequence difference

I created a wallet weeks back and seemingly restored the seed onto my other 2 devices. Recently I got to notice that I had mistakenly logged into another wallet with identical seed words but I ...
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1answer
49 views

How do i differentiate between a scam and a real bitcoin miner?

Someone offered to trade for me through bitcoin. He said i should send a bitcoin to crytomine company then he is going to claim it from the company so that he trades it with a commission of 10% of ...
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40 views

Is it possible to brute force the Secure Element of Ledger Nano S?

Only things I could find about this subject always tell that Ledger has a secure element like SIM cards and credit cards have. Also something about another OS running near the main application. But ...
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2answers
189 views

Can signature be re-used to cash out everything in the address?

I Know for the P2PK locking script it was like this [pubkey] <OP_CHECKSIG> and then an unlocking script is provided as simple as this: [sig] But if it works like this, others can simply grab ...
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1answer
34 views

How to add a second user with SSH access to my Ubuntu PC running Bitcoin Core?

I have a friend who is interested in learning Bitcoin CLI, and I told him I would look into giving him access to my node - in a non-destructive way - perhaps testnet only ? Totally trust this person, ...
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36 views

What are some potential scenarios that a state actor can harm bitcoin if they control more than 51% of the hashing power?

As reported recently, China controls more than 51% of the hashing power and just in one province in China controls 54%. Assuming China has bad intentions and forces all these mining operators to ...
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1answer
60 views

Why is a 20 byte hash acceptable in p2wpkh but p2wsh needs 32 bytes?

Why is it acceptable to use a 20 byte hash to represent single-sig witness programs whereas a 32 byte hash is used for pay to witness script hash?
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1answer
187 views

How do I securely update Bitcoin Core?

I am currently running a Bitcoin Core wallet 0.18.1. What do I need to do to update it to 0.19.0.1 version? Would be very grateful for instructions as I am relatively new to this.
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40 views

Bitcoin wallets- question about control and centralization

Community, Just a quick simple question very important for me to understand about the security of wallet types. Are there bitcoin wallets which can shut down and block/freeze/control your bitcoin ...
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55 views

How long would it take for all the Bitcoin Key pairs to be calculated?

Is this even something one should be worried about?
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1answer
52 views

Why one miner can dig out many blocks continually in one moment?

I am new to bitcoin and blockchain, I browed the website just now. There is a question confusing me, I find that one miner dig out blocks many times even in one hour. For example, this miner dig out ...
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41 views

How could PSBT deal with data capacity limit of QR code?

QR code has very limited data capacity. (According to Wikipedia) one single QR code can only carry <3KB of binary data. It's not rare for a PSBT to hit this 3KB limit, especially for ones which ...
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1answer
51 views

Address Reuse issue

I dont understand how security works with multiple address using. I am trying to guess how security works here but need some feedback, so here are a few questions, and my own guesses. If I have total ...
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1answer
35 views

Race attack with transaction fees

let's say I run a simple race attack (say in a restaurant). I transfer BTC to the restaurant but seconds before (or after) I send the very same coins to myself. To make this deal more likely for ...
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1answer
58 views

Why can't a longer key combat quantum computers?

Google's new quantum computer performed a calculation in 3.5 minutes that would have taken 10,000 years on a normal computer (so they claim: https://www.space.com/quantum-computer-milestone-supremacy....
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234 views

How can someone lose funds in Lightning Network?

In Bitcoin once you own a private key associated with an address that had bitcoins on it, your funds are theoretically safe for ever. But on the Lightning Network, I see that once you send bitcoin to ...
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1answer
114 views

How can I protect my funds in the event a quantum computer breaks the ECDLP that Bitcoin relies on?

An interesting question was posted recently, discussing the idea of hashed addresses being (not meaningfully) quantum resistant. As Andrew's answer on that question points out, paying to a hashed ...
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1answer
66 views

Whose to stop the coinbase devs from just draining all accounts and running of with the money?

I have been wondering, what would happen if the coinbase developers agree to drain all the funds of all their accounts and run off into hiding? Its not like anybody will be able stop them or return ...
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117 views

Can a blockchain's transactions be reversed?

Blockchains are often described as 'immutable' (meaning the history cannot be rewritten after the fact), but is this really true? How easy is it to change the history? I have read about the Etheruem ...
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66 views

Can two bitcoin transactions from a Segwit address (p2sh-p2wpkh) have a reused R value?

Good day. I'd found these two transactions: https://www.blockchain.com/es/btc/tx/2b08d658045724aba40b58690ad84ec2af1f01ab58df37387dadd2b27789f44c and https://www.blockchain.com/es/btc/tx/...
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39 views

Could a malicious attacker subvert the Bitcoin network by failing to create a block?

I know its astronomically improbable, but say a malicious node "wins" the proof of work inherent to the Bitcoin protocol. If a malicious node simply waited indefinitely, or maliciously disconnected ...
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96 views

Is the 51% attack the only technical reason no country will adopt Bitcoin as a state currency? [closed]

Is the 51% attack the only technical reason no country will adopt Bitcoin as a state currency? Lets suppose a country with GDP size less than 300 Billion USD adopt the Bitcoin as an official currency. ...
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4answers
100 views

How the blockchain knows that its been tampered with?

I know that the transactions stay in the block and hashed alongside few other things and that hash is stored in the next block. And I understand that if you try to tamper with one of the transactions, ...
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32 views

Beneficial proofs of work [duplicate]

I'm new to this community and a Bitcoin novice. I believe to have understood the concept and purpose of proof of work but also, that the high energy consumption of proofs of work is a major problem ...
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45 views

BIP32 HD Wallet vs HMAC vs Hashing

I've been working on a website which will be caring out various cryptographic operations. On the website users can post Ads. Each Ad has a monotonically increasing unique ID. For each Ad, I would like ...
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2answers
102 views

Why is no security lost by using 32-byte public keys in Schnorr signatures instead of 33?

There is currently a discussion on the mailing list about truncating the 33rd byte from public keys when used in bip-schnorr. Public keys are (x, y) coordinates and compressed public keys simply ...
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1answer
55 views

Why doesn't the Bitcoin-qt client ask for the Wallet passphrase upon startup?

I've just encrypted my wallet.dat file using the "Settings -> Encrypt Wallet" menu option. I then closed the client and re-opened it. I was expecting to be prompted to put in the wallet password ...
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23 views

Organization to keep track of wrongfully obtained bitcoins

I am curious whether there are any organizations that are actively trying to monitor bitcoins from illegal sources. I understand that 'when done properly' you can make bitcoins practically ...
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1answer
97 views

Prove that xpub matches xprv?

I'm researching a paper wallet system where I generate an HD xpub/xprv using an offline laptop. I write down the xprv by hand. I capture the xpub via QR code using my phone, to transfer to an online ...
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34 views

Wallet recovery from seed phrase [duplicate]

How does a wallet become recovered based on a seed phrase? From what I understand, the seed phrase is another way of representing the private/public keys. Since address reuse is frowned upon, and we ...
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1answer
99 views

What are the potential security issues when running a Lightning Node on my home network?

If I was to run a lightning node on my home network (and for example, not running the node through TOR), what should I worry about? Furthermore, what OS, settings and software should I use to ...
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1answer
39 views

What makes Bitcoin transaction secure against attackers/hackers?

Wanted to know what is it that makes bitcoin transaction secure and make it less vulnerable to attackers and hackers
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306 views

To what extent does asymmetric cryptography secure bitcoin transactions?

Is there a specific attack or bug which asymmetric cryptography prevents during bitcoin transactions?
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59 views

Possibility of a DDoS attack

Theoretically. This is not a mechanism of any kind of attack, but It's about the "lost" coins. May be. It is just for an educational experiment. What if someone has the ability to send transactions ...
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2answers
65 views

How do I find out where a bitcoin address is from?

I am not looking necessarily a name but more like is it an offline, coinbase, blockchain.com, etc... I had $80 sent from my account yesterday and it says it went to ...
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1answer
137 views

Does assumevalid lower the security of Bitcoin?

Bitcoin's assumption was to download the blocks and verify it in order to prevent getting fooled. But by default, the assumevalid option is enabled in the software, which, as I understand it, makes ...
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1answer
105 views

Is this a collision attack or a 2nd-preimage attack?

This question revolves around Bitcoin Optech newsletter #51 (1) and an email thread from the bitcoin-dev mailing list (2). I asked the same question in a reply-email of the newsletter and the response ...
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2k views

Long term BTC investing

my question is, what is the safest way of buying and holding bitcoin for the long term? And I mean 10-20 years, either a lump sum or through dollar cost averaging, is a paper wallet the answer? Or ...
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1answer
56 views

How many nodes is too many?

Has anyone done the math on this? For example, if we had 10’s of millions of nodes all connecting to 8 peers would there be some latency issues in propagating blocks across the network in the 10 ...
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1answer
57 views

Is it possible to separate blockchain and wallet functions?

I'm looking for a way to use bitcoin-core in monero-way (It uses separate blockchain daemon and wallet daemon). I'd like to run bitcoin-qt interface on my laptop and connect to external node with ...
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6answers
7k views

51% attack - apparently very easy? refering to CZ's “rollback btc chain” - How to make sure such corruptible scenario can never happen so easily?

I was shocked to see binance CZ comment to literally "roll back" the bitcoin chain by just "calling" in some favors from "friendly" Asian miners . This ONE person could effectively do it??? I mean ...

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