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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35 views

Can you think of a safe way to safely keep my “spendable” Bitcoin in my situation?

I have my "cold stash" wallet.dat on multiple fully offline, encrypted hard disks/sticks inside a fireproof safe. I never seriously considered printing them onto paper because that would be ...
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36 views

What is the alternative for an exchange which doesnt want to run a node of a coin traded?

It seems to be best practice for an exchange to run a node itself for a coin traded there. But, is there an alternative? A third party service? If yes, which are recommended and why?
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What are the benefit of mining an empty block

Something peculiar just happened on the newly mined block number 655534, it contain only the coinbase transaction, nothing else. I have searched for a similar question but only found this one Why ...
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80 views

Accidentally reused bitcoin address

I've understood that address reuse undermines privacy and potentially also security in the future. Recently though, I accidentally reused the same public address when receiving funds from an exchange. ...
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When a BIP44 XPUB and one of its descendant keys get leaked, what's the worst that can happen?

I understand that BIP44 has one edge case vulnerability where if a hacker gets his hands on an Xpub and a private key from its descendants, he can compute the Xprv pair of the original Xpub and ...
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206 views

Security risks with running bitcoin core, and how to protect yourself

I'm new to bitcoin and want to help the network by running a full node. I plan to download bitcoin core from the bitcoin.org website, and run it on a spare laptop, by my concern is how do I protect my ...
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42 views

How can Forks and Orphan Blocks be used to attack a Blockchain?

So I'm trying to learn about the security aspects of Blockchains and one of the papers I'm reading (https://arxiv.org/pdf/1904.03487.pdf) states that Forks and Orphaned Blocks can be used to attack a ...
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61 views

What is an uninitialized read? Can you point out some examples found in Bitcoin Core? How do you detect them?

What is an uninitialized read? Can you point out some examples found in Bitcoin Core? How do you detect them?
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29 views

How does the security of a mobile wallet work?

Let's assume we have a non custodial hd mobile wallet. Where is the master key stored? What are the components of the telephone that allow the derivation of keys?
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Where are the exchange keys kept? [closed]

Following what happened in Kucoin, a doubt arises. Where are the exchange keys kept? Are HSMs not used for key storage?
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51 views

Is the Lightning Network sufficiently secure and well tested for wumbo channels?

Has the Lightning Network reached a level of security and maturity where I can open wumbo channels (channels over the previous 0.1677 BTC limit) and be reasonably confident that I won't lose funds or ...
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56 views

How to create watch-only wallet on a server with a full node?

Given: there're online shops and a server with a full BTC node that I plan to run. I'll be using a full node to monitor incomming transcations thus receiving payments in an automatic manner. Only. ...
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Should I Encrypt my Wallet for Cold Storage?

I understand that the Bitcoin QT wallet is already encrypted to some extent when I use a password. Is it best-practice to further encrypt the wallet file for long term storage?
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150 views

How does nix-bitcoin provide greater security for installing Bitcoin nodes?

nix-bitcoin claims on its GitHub repo to facilitate the installing of Bitcoin nodes and higher layer protocols (e.g. Lightning) with increased security? How does it do this? [edit: as RedGrittyBrick ...
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56 views

Why is not possible for a hacker to intercept the hashes calculated by a miner, and send it all himself as if he was a miner?

(I tried to make a more specific question, but is a bit confusing to me. Sorry.) When a miner calculate a hash, where exactly does he send to in order to validate it? To all the nodes in the network? ...
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Is history reversal a concern if the absence of attackers is assumed?

As described in the Bitcoin paper, the Bitcoin network may temporarily diverge, or "fork," as nodes may work on different blockchains. The network reconverges, however, as a node will always ...
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Is it safe to store mnemonic seed in the email if I change random 2 words?

If I store 12 word seed in the email like gmail and my phone as well but change 3rd and 7th words in the seed for example with other bip-39 words and remember it, would that be safe? I can't think of ...
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Can one consider that the interest of other actors/stakeholders would change something about the concept of “blockchain”?

I am new to the Bitcoin world and am trying to get an overview within a research project. I see that Bitcoin was born out of a certain motivation to decentralize money and that decentralization, open ...
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59 views

Does mnemonic phrase contain everything in my wallet including future keys?

I am confused about something important ... Most wallets allow wallet recovery using "Mnemonic phrase", but (in general) with this phrase, do I get access to all my data ? E.g future ...
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48 views

Electrum paper wallet exploit

I want to generate a paper wallet with Electrum using my personal computer that I've been using for a few years now, meaning that I'm online with it daily. I know that the optimal solution is to use a ...
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30 views

How would somebody compromise my identity if I generate new receive address in Bitcoin Core?

I open Bitcoin Core and generate a new receive address. I publish this without mentioning my name, and make every effort to conceal my identity in every other way. Some time passes (possibly months or ...
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1answer
38 views

Do I really have to place my wallet file in the data directory?

I run bitcoin-core QT and I downloaded the full ledger data to an external HD so I can move between machines. My wallet.dat file is secured someplace else. I start-up the QT client giving the external ...
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1answer
61 views

What information can an attacker gain from watching the users behavior in block chain?

Given the blockchain is a public ledger, if user chooses not not change their public key (address) every time they make a transaction, what information can an attacker gain from watching the users ...
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68 views

Someone made a small, apparently fraudulent, transaction to my public address. What is the purpose behind it?

I have a small e-commerce site and someone made three cryptocurrency purchases just seemingly to know my public addresses as she never paid the cost of goods. The three addresses she viewed are public ...
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47 views

How to best practice restoring a wallet in bitcoin core

I have a test wallet in bitcoin core that I want to play around with and get comfortable with before I move my btc from blockstream green wallet. I primarily use that wallet because so far it has been ...
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175 views

Is sharing a signed input safe?

Is it possible to decode the private key from a signed input? For example: From this signed input hex... ...
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27 views

What prevents me to create the longest chain and multiple nodes, and deceiving everyone?

Let's say I create the longest Blockchain for Bitcoin ever (let's assume it's possible). And then I add 50,000 nodes to the Bitcoin network and I use the aforementioned chain, wouldn't I be able to ...
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54 views

How exactly would anyone know from where I got a given “bit of Bitcoin”, or who I send it to?

Let's say I buy 0.1 BTC using Bisq. Okay, so the person I bought it from will know my name since I have to give it up to make the international bank transaction. And I will know their name because ...
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42 views

What would a bitcoin quantum resistant address look like? [duplicate]

In an hypothetical future where a quantum computer is able to break the cryptography protecting the bitcoin private key, one of the solution would be to move our coins to quantum safe resistant ...
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1answer
56 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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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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34 views

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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41 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
48 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
138 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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134 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
67 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
50 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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39 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
58 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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1answer
116 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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195 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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39 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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67 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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96 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
330 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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76 views

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

Is this even something one should be worried about?
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55 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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63 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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