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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
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Why are the inputs of Bitcoin transactions signed?

This is my understanding of what a transaction looks like: inputs: input0: txid: <funding tx0 TXID> outputID: <output ID of UTXO in the funding tx0> scriptSig: <...
4
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1answer
1k views

Why is increasing block size in the Bitcoin network considered to decrease security?

I have been doing some research on the Bitcoin Cash hard fork and the main contention of increasing the block size appears to be the possibility of less security on the network. How does an increased ...
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1answer
28 views

How does using a Turing-complete programming language compromise the security of the network? [duplicate]

I have read many places that the decision for Ethereum to use a Turing-complete programming language sparked a lot of concerns over security. From my understanding, not using a Turing-complete ...
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0answers
51 views

Lost bitcoins. 100BTC Reward [closed]

Do anyone know how to solve this problem? Reward is 100BTC. I'm attaching question also to bitcoincore-developmen to find out if there are any solutions, which could already do something with this ...
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0answers
9 views

Does NPM Package Vulnerability effect Mac OS Desktop version?

Im still using MAC OS desktop client 3.9.1 Version. When trying to use Github link from inside the app the newest version i get is 4.8.1 https://github.com/bitpay/copay/releases/tag/v4.8.1 What do i ...
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0answers
34 views

Why Spectre has a “weak” liveness?

According to this article: (https://medium.com/@avivzohar/the-spectre-protocol-7dbbebb707b5) written by one of Spectre's author (Aviv Zohar), it is mentioned that Spectre has weak liveness. What is ...
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2answers
31 views

Exact definition of “Liveness” and “Safety” properties in a consensus?

Two main properties of a consensus are "Liveness" and "Safety". What are the exact and precised definition of "Liveness" and "Safety" properties in a consensus ? Are the following definitions ...
0
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1answer
28 views

How Spectre tolerates spam transactions?

Spectre is a DAG based (directed acyclic graph) distributed ledger (a structure as an alternative to blockchain based distributed ledger). Is there any mechanism in Spectre to prevent sending spam ...
2
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0answers
31 views

Sybil attack with IOTA?

IOTA is one of the DLTs uses DAG (Directed Acyclic Graph) as data structure. The solutions to attacks proposed by IOTA white paper seems unconvincing, in particular, in case of double-spending, it ...
1
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1answer
34 views

Security of Bitcoin Wallet

I have a doubt on Bitcoin wallet. Suppose I have an online Bitcoin wallet. Now, someone breaks into my computer and steals my Bitcoin wallet. Fortunately I have a backup of my wallet on another ...
4
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1answer
352 views

Why was an insecure merkle tree implementation chosen?

At risk of creating a "lets discuss politics" question, let me clarify that what I want to know is whether there is a known benefit to Satoshi's "duplicate the last hash" merkle tree implementation ...
0
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1answer
23 views

Does Electrum store my seed in their server?

I am new to Bitcoin. I used Electrum software to create my first wallet. When the software generated 12 words, I had written down that in paper. These word are very important, right? But the software ...
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0answers
30 views

Byzantine Fault Tolerance Threshold of Bitcoin: 1/2 or 1/3?

According to this answer: https://bitcoin.stackexchange.com/a/58908/41513 a Byzantine Fault Tolerant (BFT) consensus threshold is 1/3, that is contrary to belief that the Bitcoin network is secure (...
10
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1answer
172 views

Schnorr's batch validation

In the recent BIP about Schnorr's standardization, Pieter Wuille presents an algorithm for batch validation. In my understanding the most heavy operation is the multiplication by a scalar: to make ...
0
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2answers
24 views

Hiding identity in digital currency era

I have a question about the security of digital currencies, however still I have find a clear answer for that. No matter what is the currency, e.g bitcoin, monero, ..., at the end of the day, I have ...
1
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1answer
24 views

What would happen if I publish a modified version of an earlier block? Would it be rejected immediately by peer nodes?

I am reading the book "Mastering Bitcoin" and have finished reading Chapter 2 and 10, but I still don't find the answer. Suppose the current main chain has 5 blocks: B0 <- B1 <- B2 <- B3 &...
1
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1answer
46 views

Have there been any examples of people manipulating transactions in a way that waiting for more than 1 confirmation would avoid?

A lot of bitcoin exchanges require some minimum amount of confirmations before they consider money deposited. Is there any evidence that this actually does anything? Has someone ever before ...
0
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1answer
63 views

Why can a wallet not compute the private-key from a public-key?

my goal of questions this is why any wallet not able to compute private key created with public key generate?
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2answers
39 views

Can't understand specific problem of Bitcoin anonymity

There is an problem shown in bitcoinwiki: Someone runs both a money exchanger and a site meant to trap people. When Mr. Doe buys from the exchanger and uses those same coins to buy something ...
2
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1answer
52 views

Can I, and should I, verify bitcoin core source code before compiling it?

If I use bitcoin core binary release I can verify them with the gpg keys of the core developers. Is there a similar process for the source code? A follow-up question: Is it preferable to use signed ...
2
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2answers
76 views

What can you do with the private key?

I am trying to understand all security regarding blockchain and bitcoins. Let's say you have a bitcoin wallet which is secured, only you know the private key. This bitcoin address was created on one ...
1
vote
1answer
25 views

Review sites for the hardware wallets? [closed]

As I understand it there are four (4) hardware wallets produced currently (2018). Which businesses, web sites, or academic papers in the field review and compare the security of these devices? Is ...
2
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1answer
94 views

A couple of questions on Schnorr sig

In the BIP by Pieter Wuille it is told that the key prefixed version of Schnorr signature is needed when the scheme is used in combination with BIP32's unhardened derivation. Could someone provide an ...
0
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1answer
14 views

Physical bitcoin vs. Paper wallet?

What is the main difference between a Physical bitcoin and Paper wallet ? And which one is more secure ? And why ?
1
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1answer
181 views

How to store private key in MySQL database?

I want to receive payments from Bitcoin on my web app, but I do not want to use corporate gateways (coinpayments, bitpay, etc), I'm wanting to make my own gateway. I do not know how best to do this ...
0
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1answer
24 views

Statement: for an attacker to change history, they must solve computational puzzles at a faster rate than the rest of the participants combined

I'm new to cryptocurrency and blockchain. I just started reading the textbook Bitcoin and Cryptocurrency Technologies by Narayananm, Bonneau, Felten, Miller and Goldfeder. The statement in the title ...
3
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1answer
35 views

Question about identical txids/merkle tree in Developer guide

I am new to the technical details about Bitcoin and has been reading Developer guide on bitcoin.org. I have a question about below contents mentioning merkle tree, identical txids. I googled and ...
1
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1answer
37 views

Delegated Proof of Stake (DPOS) vs. Proof of stake?

What is the main difference between Delegated Proof of Stake (DPOS) vs. Proof of Stake? Is there any significant advantage for security? (since PoS in general suffers security problems.) And which ...
3
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1answer
781 views

How does timejacking enable double spending?

http://culubas.blogspot.com/2011/05/timejacking-bitcoin_802.html I went over this blog, but I am still not clear how double spending is achieved by this attack. From what I read, the attackers submit ...
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0answers
17 views

How to protect a crypto currency from Seed failure

I have created a new currency based on Forknote/Cryptnote. It has a small number of Seed Nodes. I am investigating how to mitigate the risks of currency failure due to Seed Node collapse from ...
2
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1answer
74 views

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 ...
1
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1answer
30 views

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 ...
5
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1answer
391 views

How can all possible numbers in 256-bit space be squeezed into 160-bit space?

Bitcoin addresses are essentially 160-bit hashes of a 256-bit public key. Huh? How can all possible numbers in 256-bit space be squeezed into 160-bit space? Does that mean any given bitcoin address ...
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2answers
42 views

How to secure a Linux node running satoshi 0.16.1?

Everyone in the BTC space seems to suggest that running a full node is the way to go. But Linux has a huge attack surface and I don't want to lose my BTC by having my wallet on an insecure OS. What is ...
3
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3answers
129 views

Has PoS really been proven secure under comparable assumptions as Bitcoin?

I am just reading this paper which claims to be a formal proof that Cardano's latest Ouroboros PoS protocol ("Genesis") gives similar security guarantees than Bitcoin's PoW protocol. Unfortunately, it ...
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2answers
42 views

Do lightweight wallets validate signatures? If not, why?

I've learned that "some SPV clients simply don’t check signatures themselves at all": https://bitcoincore.org/en/2016/01/26/segwit-benefits/#efficiency-gains-when-not-verifying-signatures I wonder if ...
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2answers
67 views

i lost access to my bitcoin [closed]

I did not have any idea about bitcoin but I wanted to get in, I met this guy who knew about it on facebook asked him if he could help. he sent me the link on blockchain to signup showed me how to buy ...
2
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1answer
49 views

Checking the first and last characters of a cryptocurrency address?

When confirming that an address entered on a site/app is what I expect it to be, I often check the first and last 3-4 characters to see if they match. Is this practice dangerous? Could an attacker ...
3
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1answer
52 views

Why is it more profitable for a node with more than 51% computation power to abide by the rules in the bitcoin network

The Bitcoin whitepaper states - "The incentive may help encourage nodes to stay honest. If a greedy attacker is able to assemble more CPU power than all the honest nodes, he would have to choose ...
2
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1answer
82 views

Is possible to destroy the Bitcoin for just $500K? (51% attack)

Everytime I read about the 51% attack the answer was something like: is really expensive to get 51% of power on BTC and nobody will invest so much so to destroy the bitcoin. But I found this site ...
0
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1answer
138 views

Hello, someone is using an bitcoin account to blackmail me [closed]

Someone using a bitcoin account is trying to blackmail me. The account number is 1Mtsd3wXgkJnApaNpqaSSWLC6gCLBBxuaGG. I still have the email they sent me. I can also provide that email if needed, or I ...
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1answer
1k views

How to hack a Password of Private Key

I have a Private key and then after I entered it, there's another saying "Input a required Password of Private Key" So how can I hack or generate that?
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3answers
46 views

Am I protected?

I've been asked to pay for a purchase in Bitcoin. Why would someone use this method instead of say Paypal and as a consumer am I protected in any way? I have never used Bitcoin or looked into it so I'...
4
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3answers
138 views

How can I safely store and trade Bitcoin and other crypto currencies?

How can I safely store Bitcoin? Exchanges require me to deposit to trade, is this safe? If I can't trust exchanges, what is the best way to safely store my cryptocurrency and transact it?
1
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1answer
43 views

Given that you have the necessary computing power, how does a tampered blockchain get accepted by the network?

I read that you can only tamper with a blockchain if you have more than 50% of the computing power in the network. So say you have 51% of the computing power, then you can create a longer blockchain ...
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1answer
51 views

Is Lightning network really a hope for better scalability and low latency?

BTC can't do transaction in 1/4000 times to what VISA does and then still claims that it will disrupt industry. The proof of work has limitations to scalability and in no way it can record transaction ...
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1answer
1k views

Private key to mnemonic words, is it safe?

Is it safe to do the following? Suppose I do not want the HD wallet, but I do want the convenience of using mnemonic words to remember the private key. I know I can convert the private key's hex ...
0
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1answer
96 views

Why do the biggest exchanges reuse Bitcoin addresses if doing so is unsafe?

It's generally accepted that using one address for multiple transactions is unsafe, because sending a transaction reveals your public key (whereas only the hash of your public key is required to ...
0
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1answer
31 views

How bitcoin wallets connected between

I'm thinking, is it dangerous to buy bitcoin, in case if government want to block it? How bitcoin wallets connected between? If I'm right - there are support servers, who providing connection between ...
5
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1answer
207 views

How do the JavaScript SecureRandom() vulnerabilities affect me?

A recent post on the Bitcoin-dev mailing list talks about multiple vulnerabilities in JavaScript SecureRandom() class. Apparently this class has been used in multiple cryptocurrency wallets that use ...