Questions tagged [attack]

Relates to attempts to harm the Bitcoin network. In cryptography, an attack is a method/technique to break the code. Bitcoin also has to deal with other types of attack, such as double spends and denial of service.

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Selfish mining attack: Probability of block being mined - CS251 exam question

I am currently studying for the CS251 Cryptocurrencies and Blockchain Technologies exam. In a past exam, there is this question without an answer and I would really appreciate your help so that I can ...
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What happens if a miner deliberately ignores a transaction, and "wins"?

Suppose a miner decides to solve the nonce for a particular block, where the miner deliberately excluded a particular transaction from this block. The miner "wins", i.e. they found the nonce ...
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Can an attacker flood the Bitcoin network with fake transactions?

We are in 2050. People show an ever-growing distrust in the global banking system and start transitioning to only using Bitcoin: most companies accept it as a form of payment, and people settle their ...
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Known cases of block-withholding attacks

At the moment I am doing a course about Bitcoin. The topic of the last session was the block-withholding attack and the course (being from 2014) claimed that there are no known attacks so far. Is ...
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Forced fork of older, low difficulty blocks

Let’s assume main chain (A) height is 1000 and the difficulty adjustment is 50 blocks. At height 450, the difficulty is very small. By modifying timestamp of blocks 450-500, I mine a fork (B) such ...
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Transaction Denial of Service

If the BTC network can only only handle on average 2,759 transactions per block. During a period where whales attempt a mass dump, could they essentially perform a DoS attack where they make a large ...
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What is the fraction of the Bitcoin mining power that might be engaged in Selfish-Mining?

Is there an estimate for the fraction of miners engaged in Selfish Mining within the BTC network? In light of the publication The Impact of Selfish Mining on Bitcoin Network Performance (2021), ...
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174 views

How does the bitcoin core protect against initial DNS seed changes?

While the bitcoin network is essentially P2P, one still needs to identify an initial node to connect to. I understand that a method for such initial connections is connecting to known DNS seeds, e.g ...
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Attacker Changing Address to Receive Block Reward [duplicate]

A miner creates a block B which contains address α, on which he wants to receive his rewards. An attacker changes block B, such that instead of α it defines a new address α’, which is controlled by ...
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Two threats to Bitcoin: Quantum Computing and Mining farm seizures - what new BIPs are needed before it is too late? [closed]

How resistant is bitcoin blockchain against physical attacks? Contrary to other consensus mechanisms, Bitcoin's PoW model is dependent on massive Mining Farms with tons of ASIIC hardware. These farms ...
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Which opcodes where disabled by Satoshi Nakamoto for cve 2010 5137

Lot of opcodes where disabled over the years. But which opcodes where disabled Satoshi himself and specifically for the any one can spend any coin bug?
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Name of attack where you pay a high fee to block others

Is there a name for an attack where someone with a lot of capital makes loads of transactions with a high fee, just to prevent other transactions from taking place? This seems like a moderately cheap ...
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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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Exchange Confirmation Requirements

What does the minimum confirmations required for a deposit mean for the security of exchanges? For example, Coinbase requires 3 confirmations for Bitcoin deposits. Suppose an adversary deposits 10 ...
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What are the potential attacks against ECDSA that would be possible if we used raw public keys as addresses?

According to this answer about why addresses are hashes rather than public keys there are potential attacks that are possible if you have the public key rather than the address, what are these attacks?...
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If I were executing a 51% attack, would I be broadcasting my state of the network to nodes?

In the scenario where an entity has control of greater than 51% of the hash power and wishes to build a longer chain where they double-spend previously confirmed transactions, do they broadcast the ...
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What is the SPV Mining Exploit?

Can anyone explain this simply? I am not finding enough explanation exactly on this type of attack. If possible, add some additional reading to your answer so that I can understand more.
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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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Bitcoin 51% majority miner attack - question on the role of user activated soft forks as defense tactic

If one mining entity has alone 52% hash power of the overall network, then this party can block transactions for example and try to "build" up a forked, longer chain while time passes, right?. As I ...
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Is OP_RETURN dangerous for Bitcoin?

Please explain something about OP_RETURN to me? https://bitcointalk.org/index.php?topic=1166928.0 I saw a discussion that the contents of OP_RETURN can open the value of access to the private key. I ...
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Probability an honest node finds the next block vs. probability the attacker finds the next block

I am trying to understand Satoshi's paper [1]. On page 6 of the paper, he calculates the probability that someone can attack the blockchain from z blocks behind. He begins by defining: My question: ...
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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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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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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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Can a malicious Internet Service provider launch a double spend attack?

If a malicious internet service provider completely controls a user's connection, can it launch a double-spend attack against the user? How much computational effort would this take?
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How to re-secure a multisignature wallet if private key is stolen

Here are two attack scenarios on bitcoin private keys: 1) Assume that, BitCorp has just noticed that a Mallory has just compromised one of their servers holding their Bitcoin Private keys. Luckily,...
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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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Malicious full nodes causing denial of service attacks

To control >51% of the mining power in bitcoin is impractical due to the immense investment that will be required. Also, The Bitcoin Core client has DoS protection against malicious nodes forwarding a ...
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What are the consequences if I spoof an IP address in the node_announcment message?

According to BOLT 07 the node accountment message looks like this: type: 257 (node_announcement) data: [64:signature] [2:flen] [flen:features] [4:timestamp] [33:node_id] [3:...
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What stops miners from no longer submitting failed hashes to the network, to reduce the difficulty and block time?

As I understand it, the difficulty adjusts based on the hashrate to keep the block times at 10 minute intervals. But if Alice and Bob are the only ones mining on the network, what's to stop Alice from ...
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How to find one private key from the list of 15 million public keys for the sake of experimentation?

Recently found a list of compressed public keys. The total number of 15 000 000 public keys. Practical for all compressed public keys Balance: 0.000100 BTC I do not set malicious goals. All just for ...
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Serialized transaction bigger than the actual transaction object? CVE-2013-4627

I'm surveying old Bitcoin DoS vectors and came across CVE-2013-4267, for which there appears to be little public information available. This thread should shed some light on this CVE. There's a ...
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What happens when the verification of a manipulated transaction fail?

If a malicious miner changes the amount in a given transaction, the hash value of the block changes. Thus, he has to find the required hash value again in that block. Let's say he successfully found ...
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Set up a Bitcoin full node: static or dynamic IP address?

I am trying to set up a new Bitcoin full node and my institution ISP is trying hard to not give me a static IP address for this purpose. I guess because of the concern that the node will be DDoSed, ...
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Bitcoin is attacked by China miners by screwing with the network, what will Bitcoin do?

There was a report recently (https://arxiv.org/pdf/1810.02466.pdf) that stated that China controls 74% of the hashing power. They can choose to collude and attack the network by either doing a 51% ...
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Why was this transaction accepted?

In testnet, txid:fb7a8658ec015133e36e2cf7ddf7e8c887c3a5becec2f30f24ebfe43e72f4b59 transaction has two inputs. This two inputs indicate the same txid and vout, ...
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attack bitcoin through writing data directly into output's scriptPubKeys

In this post, Steve Ellis wrote : "[...]Writing data directly into a output's scriptPubKey is not prunable[...]where as non-prunable outputs will forever create bloat and slowdown the set ...
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Is there a limit to how many blocks can be rolled back from a 51% attack?

I was wondering if we where to ever face a 51% attack is there some sort of limit as to when the longest chain doesn't matter? For example if I owned 51%+ of the network, mined 1000 blocks privately ...
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Possibility of broadcasting new block to only a fraction of honest nodes?

Consider in a block-withholding attack (aka selfish mining attack), attacker after creating a new block decides to broadcast this new block only to a fraction of network, such that eventually only a ...
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What prevents DoS based on near-valid block timestamps?

Upon receiving a newly mined block, the block timestamp validation is performed here: https://github.com/bitcoin/bitcoin/blob/master/src/validation.cpp#L3263-L3270 Q1: As for the second check (block ...
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Mining Theory: A theoretical mining based attack

Okay, so, here is my scenario: Imagine a group of miners who are mining a coin are responsible for a large portion of the hash rate on the network (let's say not quite 50%). Looking at the parameters ...
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Why do we call it a 51% attack instead of a 50% attack?

From the Bitcoin paper: p = probability an honest node finds the next block q = probability the attacker finds the next block qz = probability the attacker will ever catch up from z blocks behind qz ...
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Hypothetical Scenario - Address collision with address with already confirmed outgoing transaction

In a typical case of finding a collision with an address, as long as the private key provided has a consistent public key that hashes to the address, then the coins in that address can be spent. The ...
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Can corrupted unspent transaction outputs list leading to higher than expected fee be seen as an actual threat?

Let's imagine, an attacker managed to corrupt your local list of unspent transaction outputs (or a blockhain explorer you use) in a way that certain unspent transaction outputs seem to hold less coins ...
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How prevalent are coin attacks with botique altcoins?

I have deployed several altcoins using various PoW algorithms on my LAN for my buddies and I to mine/learn from. We ultimately want to go the distance of deploying an altcoin to the world, writing the ...
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How much computing power is required to bruteforce a Litecoin private key in reasonable time?

Say I want to break a Litecoin private key having the public key using brute force. How much computing power is required for that? Does any hardware exist which can find a matching private key in, say,...
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What stops people attacking my new coin?

Say I just made a new altcoin. I mined it for a few days at some reasanoble difficulty - 2000 for example. I got to the 10 000th block and I am happy with my premine and network. Then, an attacker ...
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Why can't mining pools provide fake transactions within the generated blocks?

Suppose Alice wants to add a fake transaction where she receives X ammount of BTC. I understand that in order to add that transaction to the blockchain she would have to compete against all the other ...
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How does headers-first prevent fill-disk attack?

Checkpoints prevented an attack where a node could mine many many low-difficulty blocks from an early point in the blockchain and serve those blocks to syncing nodes who would see their disks fill up. ...
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What is time warp attack and how does it work in general?

I am trying to understand the recent time warp attack on verge but since the attack is universal across all POW block chain i figure I could also ask here since people here are .. more knowledgeable. ...