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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64 views

Why is it impossible to get a straight answer as to whether Bitcoin is anonymous or not?

Yesterday, I asked a question which got linked to this answer: Is it true that all the bitcoins in existence are on the blockchain (the ledge), but it just depends on who the owner (address) is? ...
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24 views

What would stop some major company from blacklisting specific Bitcoins based on the “inputs” used and their “origins”?

I remember news about some exchange actually banning users based on some kind of "reputation score" on the inputs/coin parts they controlled/used, or got Bitcoin sent to them from. So even ...
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Changing bitcoin core password

Let's say I have 5 copies of my .dat file on individual flash drives. I download the blockchain and run a full node and have the core wallet. I copy my .dat file into bitcoin core. I type in the old ...
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52 views

Are “coin mixers” actually a real thing? Can they be trusted?

Ever since I started hearing about Bitcoin, people have been mentioning "coin mixers" to me, and told me to use them. However, even early on, when they were practically throwing away ...
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Are there any privacy benefits in using a separate wallet in Bitcoin Core to separate myself from my service?

I currently run Bitcoin Core with the following wallets loaded in: hot.dat. Contains the smallest possible sum of Bitcoin. Unencrypted and used by myself for various personal Bitcoin purchases, and I ...
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31 views

Someon offered me btc mine trough his mining device

Someone from the social network offered me a btc mine through his mining device. He asked me for an email address so he could create a mining wallet address for me. I gave it to him. I don't know what ...
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29 views

Are there any privacy benefits in using a separate wallet in Bitcoin Core to “separate” myself from my service?

I currently run Bitcoin Core with the following wallets loaded in: hot.dat. Contains the smallest possible sum of Bitcoin. Unencrypted and used by myself for various personal Bitcoin purchases, and I ...
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1answer
35 views

Why is SHA-256 mining secure?

My understanding is the when you are mining bitcoin you are looking for a string, or maybe a binary number (a) such that if you 'add' a to the block (b) you get a number (c) whose hash begins with a ...
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59 views

Is there a way to tell that our bitcoin is safe after we put it in a hardware wallet for cold storage after 3 or 5 years?

If I consolidated 1 bitcoin into an address using a hardware wallet, and put it in cold storage. Can I know after 3 to 5 years that the bitcoin is safe? So far the research I have is: can I go to ...
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30 views

Is our hardware wallet safe if the PC or Mac has 3rd party apps?

For example, our PC or Mac might have 3rd party apps installed, such as Pixelmator, GIMP, or VLC player. They are usually considered to be safe apps. However, is it true that when using a hardware ...
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58 views

Wallet suddenly shows transactions from someone else

I restored a wallet recently that I have not used in years. Back then, it was only Bitcoin, but at some point Ethereum was added. So now I see all my Bitcoin tx, but on top of that the Ethereum part ...
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bitcoin address after transaction security questions

I found an old paper wallet on an old computer of mine which is offline (I can count the number of coins with my fingers). I would like to distribute these coins now among 6-9 wallets (I want to give ...
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1answer
37 views

How is bitcoin (blockchain) secure?

I see a few different levels here and I want to clarify There's various levels where your password could be potentially exposed... at least from my mind Storage (paper wallet, metal wallet, cold ...
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31 views

Can Phoenix wallet steal my funds?

Phoenix wallet is a great UX Lightning Wallet, and they're able to deliver that UX by making a few different tradeoffs. None of those tradeoffs involve them owning your private key, but in their 2019 ...
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25 views

How to verify Wrapped Bitcoin (WBTC) issuance

I'm trying to understand how Wrapped Bitcoin (WBTC) issuance can be verified. The WBTC custodian, BitGo, published the following material: https://wbtc.network/dashboard/audit This is a list of ...
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115 views

Bitcoin disappeared from Trezor wallet

Originally I installed my Trezor wallet onto my wife's computer (since my computer doesn't have a USB 2.0 port). Later, I bought an adapter and decided to transition the Trezor wallet to my computer. ...
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Multi Party ECDSA?

Are there any alternatives to the Multi Part ECDSA implementation contributed by ZenGo?
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Transferring funds from a cold wallet to a hot wallet - on chain or off chain?

I've seen two techniques when it comes to transferring funds from a cold wallet to a hot wallet. In one technique the cold wallet signs a transaction (offline of course) and transfers funds to the ...
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40 views

“Hot”, “Cold” & “Warm” Storage Wallets? [duplicate]

I've seen a number of sites advertise they support "hot", "warm" and "cold" wallet storage solutions (the only thing I haven't seen so far are "frozen" wallets)....
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71 views

Are Hardware Wallets (i.e, Ledger Nano X) Safer than Software-Based Cold Storage Wallets?

I'm looking into purchasing Ledger Nano X as a cold storage hardware solution. What benefits does Nano X (or other hardware wallets) provide over software based cold storage solutions? Why not install ...
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How do exchanges automate transfer of Bitcoin from cold stoarge wallet?

Most exchanges use Cold Storage to store the bulk (approx. 95%) of their user assets. Only a relatively small amount (approx. 5%) of funds are held in their Hot Wallet. My question is, what process is ...
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174 views

Securing the “weakest link” of a chain through Sharding

In this question I discussed how sharding a private key with Shamir's Secret Sharing Scheme maybe a good alternative to MultiSig as a means of reducing excessive fees associated with MultiSig ...
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42 views

Security concerns with walletpassphrase

I have some security concerns with walletpassphrase: If it stores the passphrase for some unit of time. ie. so you can send funds, surely if the server is compromised, within that timeframe, the ...
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158 views

Is Sharding a Good Alternative to MultiSig?

For security purposes, we require that each withdrawal be "approved" by multiple servers so that in the event a single server is compromised the attacker won't be able to siphon funds from ...
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32 views

What does it means “get a new address and then make the Bitcoin offline” and make it extremely secure?

I have been reading about Bitcoin, and one thing was about making Bitcoin extremely secure, which is to get a new address so that nobody knows, and then making it offline right away? Is it like 0.01 ...
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Can an exchange or marketplace benefit from private key encryption?

A powerful security technique to prevent theft of Bitcoins from a user's online wallet is to encrypt the user's private key with his password without ever stroring the PK directly in the database. ...
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1answer
37 views

Storing your private key on a “security server”?

One of the suggested security precautions when storing Bitcoin of users on a server is to store the private keys on a separate server: The database storing the private keys or the seeds in case of ...
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53 views

How can I earn an income from my bitcoins without revealing my identity or relinquishing control of my bitcoins? [duplicate]

I have some Bitcoin. I don't want to part with them, but I need an income. I'm trying to have it so that, somehow, my Bitcoins generate a small sum monthly in fiat, to my bank account. While going ...
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If the “wallet seed keywords phrase” is all that's needed to restore a hardware Bitcoin wallet, isn't backing that up a nightmare security-wise?

I buy a Trezor. I put all my coins on it. It has me type out the "wallet seed", which is a series of English words in the right order, onto a paper. And maybe I even buy a metallic card ...
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96 views

Lessons from the Mt. Gox Hack - 850,000 Bitcoins Stolen

Mt. Gox was a bitcoin exchange based in Shibuya, Tokyo, Japan. Launched in July 2010, by 2013 and into 2014 it was handling over 70% of all bitcoin (BTC) transactions worldwide, as the largest bitcoin ...
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Are ASICs Resistant to Malware Attacks?

One of the arguments made in favor of relying on ASIC mining hardware to secure the Bitcoin blockchain is that commodity hardware is more prone to a 51% attack since an attacker could easily infect ...
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537 views

Is there something about Bitcoin that prevents us from implementing the same privacy protocols of Monero and Zcash?

Certain coins like Monero and Zcash implement privacy protocols that make it nearly impossible to trace origin and destination of transactions - making them completely anonymous. I'm curious as to why ...
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What stops an attacker from crippling the Bitcoin network?

An individual (or government) who wants to bring down the Bitcoin network could conceivably broadcast a ton of junk/illegitimate transactions to the network thereby consuming the bandwidth and ...
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1answer
144 views

Would first-seen prevent a double spend attack?

It takes approx. 8 seconds for a transaction to propagate through the entire Bitcoin network. If we got rid of the concept of replace-by-fee and replaced it (no pun intended) with a first-seen ...
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123 views

Recover $220 Million Worth of Bitcoin Locked in a Self Destructing Hard Drive

A NY Times article recently ran a story of Stefan Thomas who has $220 million worth of Bitcoin locked up in an encrypted hard drive: Stefan Thomas, a German-born programmer living in San Francisco, ...
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64 views

1 MB Block Size as a Anti-DoS Attack Measure

Wikipedia explains the rationale behind the 1 MB block size limit as follows: The one megabyte block size limit was added in 2010 by Satoshi Nakamoto as a temporary anti-DoS measure A SE post ...
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68 views

Is my cold wallet still cold?

I created a new wallet.dat on a dedicated, secured machine with Bitcoin Core. Then I encrypted it. Then I sent my "fortune" of coins to it. Then I backed the file up by putting it on all my ...
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Bitcoin over Tor and man in the middle attack: risks mitigated yet?

This paper explains how combining Bitcoin and Tor creates an attack vector. A man in the middle can control the information flow between all users who connect over Tor. This paper is from 2014. Has ...
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98 views

Mining Bitcoin at 1000x Efficiency

Bitcoin secures its network by forcing miners to solve a cryptographic puzzle who's difficulty increases based on the total hashing power of the network. If someone were to develop an algorithm that ...
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1answer
63 views

Doesn't storing the “recovery seed phrase” for a wallet defy all logic?

I've heard many times that you are supposed to write down a "recovery seed phrase" (a series of English dictionary words) on a piece of paper and store that securely so that you can recover ...
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43 views

Why can't a 51% attack change past blocks on the blockchain?

I have read that it is not possible to reverse transactions already added to the blockchain but I do not understand why that is not possible in a 51% attack. If an attacker was to change the ...
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What should i do with my used antminer? How should i set it up?

ive just purchased a 2nd hand s9i antminer, got it for £200, a great deal i thought, what tasks should i perform before installing? i was thinking of opening it up and looking inside, just to see what ...
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What is the practical link between the hashing power in the bitcoin network and its security? [duplicate]

Several books claim that as the hashing/computing power increases, the bitcoin network is securer. How can a non-techie sees that from a practical standpoint?
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Do hardware wallets store the wallet.dat redundantly inside? If not, are there such hardware wallets?

I'm baffled by how "cheap" the existing hardware wallets look and seem. They seem to have been made "at a budget", with no real high-end version available. If I owned something ...
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2k views

Is bitcoin.org or bitcoincore.org the one to trust?

"Download Bitcoin Core": https://bitcoin.org/en/download "Download Bitcoin Core": https://bitcoincore.org/en/download/ I've been alternating between the two sites for years. I have ...
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102 views

What prevents somebody from “re-mining” an already existing Bitcoin?

This may reveal that I know nothing about math or cryptography. Let's say that a given Bitcoin was "lost" in that it was once mined and assigned/given to a person who had it in their wallet....
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108 views

Should I be using the “encrypt wallet” feature in Bitcoin Core?

All my wallet.dats have no password. However, the internal hard disk where the "live" one is located is encrypted, and so are the offline storage devices where I have my "cold" ...
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Am I really understanding how the “Trezor Model T”, and hardware wallets in general, work?

Getting increasingly paranoid about losing my coins, I've yet again (for probably the 20th time by now) went looking for hardware wallets. The only semi-reasonable one seems to be the two Trezors. All ...
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72 views

As the Bitcoin price skyrockets, how to avoid getting malware through freeware/FOSS software's updates?

We have a situation now where the vast majority of software I have installed on my computer (Windows 10, since there are no other supported versions of Windows) are either aging one-man freeware ...
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55 views

Threat probability? 1 state controls >70% of miners. Other states go to war with them [closed]

This is almost certainly a silly question, but there are a lot of new bitcoin owners like me and a specific threat was made today which sounds credible to those of us who lack deep knowledge of ...

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