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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350 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 ...
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0answers
119 views

Sybil attack with IOTA? [closed]

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 ...
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2answers
629 views

What alternatives are there to hardcoding checkpoints into the Bitcoin client?

Checkpoints seem like a crucial part of the security & validation apparatus in Bitcoin. Is there a written policy in place, among the developers defining the maximum interval between checkpoints? ...
6
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2answers
2k views

Can you mine without transactions?

As far as I know, mining means verifying transactions and thus keeping the Bitcoin network alive. Today, at a local meetup, some people have informed me that mining doesn't need transactions. They ...
4
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1answer
401 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
53 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 ...
1
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1answer
63 views

Is the statement that LN hot wallets will be less secure than non LN hot wallets correct?

I say this because of the following reasoning: Lightning network wallets will have to completely possess my private key, whereas non-LN hot wallets will most of the time only have my key encrypted (I ...
6
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3answers
4k views

How to generate a public key from a private key using Elliptic Curve Digital Signature Algorithm

I'm trying to understand the graphical basis that underlies the discreet logarithmic Elliptic Curve Digital Signature Algorithm (ECDSA) introduced in Chapter 4 of "Mastering Bitcoin" by Andreas ...
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2answers
31 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 ...
8
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1answer
1k views

What is BlitCoin?

I saw BlitCoin mentioned on this forum thread, but didn't understand what it was. Can someone explain what does it do?
132
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8answers
48k views

What can an attacker with 51% of hash power do?

Suppose organization X has 51% of the hash power for a period of 1 week. In this week, what exactly can and can't X do?
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1answer
78 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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1answer
31 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 &...
4
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1answer
672 views

What happened to my coins, hacked?

I'm new to bitcoin, downloaded the bitcoin.org client, encrypted my wallet, and purchase a few bitcoins (5.25), for learning purposes. But now my coins seem to have disappeared to an unknown address. ...
1
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1answer
51 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 ...
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2answers
258 views

Address reuse, one address per person

I know about the privacy and security implications of address reuse. But I was thinking about a scenario where I have one address for every person I receive transactions from. This would still have ...
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2answers
53 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
103 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 ...
1
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1answer
29 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 ...
3
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1answer
129 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 ...
5
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3answers
284 views

Bitcoin value vs. Supercomputing

What protects the stability of Bitcoin's value if supercomputers or some other technological breakthrough allows them to be mined at rates we have not anticipated?
5
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1answer
686 views

What precautions should be taken to protect a Ripple wallet?

What if a Ripple wallet gets hacked? What are the suggested precautions for the average user?
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1answer
424 views

How many peers do you need to securely synchronize with the blockchain?

What is the minimum number of peers required to securely synchronize my local blockchain copy?
5
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3answers
13k views

Can we report a fraudster by their bitcoin wallet address?

I was recently notified by a friend that someone sent her a message (posing as me) on an app asking her to send them some bitcoin so they could make a purchase. Luckily she knew it was not me and let ...
0
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2answers
215 views

How can address' hash160 be used to determine information for malicious purposes? (Ie reusing of the same address)

I've been playing around with Richard Kiss's Pycoin app which is clarifying how P2PK works. I see that the hash160 of the value: (0x04) (x-coordinate) (y-coordinate) (for an uncompressed Testnet ...
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1answer
562 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 ...
2
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3answers
2k views

ECDSA x,y coordinate validity verification doesn't seem to work

The ECDSA algorithm, secp256k1 for Bitcoin allegedly uses the equation y ^ 2 = x ^ 3 + 7 mod P to determine the validity of an alleged point upon the elliptical curve. Utilizing http://web2.0calc....
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1answer
71 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 ...
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3answers
560 views

Is creating a long password for my coinbase account enough to keep my bitcoins secure?

I've made an account with coinbase and purchased some bitcoin. Only after to start reading people talk about getting hacked and how bitcoins are not secure unless you put them in a "wallet".To be ...
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1answer
26 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
48 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 ...
2
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2answers
63 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 ...
3
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1answer
846 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
27 views

How to protect a crypto currency from Seed failure [closed]

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 ...
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2answers
42 views

Trading crypto currencies with dollars

After I have bought a crypto currency at an exchange like Binance can I sell for dollars if it is going down. Basically if I have a profit from a currency what can I do with it to protect it?
5
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1answer
402 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 ...
2
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1answer
165 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 ...
4
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3answers
156 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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1answer
2k 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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1answer
47 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 ...
0
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2answers
152 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 ...
7
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2answers
696 views

Can the blockchain be outpaced by a chain of low-difficulty blocks?

Let's say someone creates a blockchain fork starting from the genesis block, when the difficulty was absurdly low compared to today; then he starts mining new blocks from there up to the current block ...
7
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1answer
1k views

What happens if my wallet gets “hacked” and my BTC is stolen?

What if my wallet gets hacked and the hacker transfers all BTC to his account? Is there is any way to get it back, or to open a dispute to specific address or anything else?
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6answers
1k views

How do I protect my paper wallet from use by a different human who has used a random generator?

Since millions of people use Bitcoin and Bitcoin Wallets that use their own addresses use several addresses per day, it is obvious that generators can generate the same characters for the Bitcoin ...
4
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3answers
2k views

How is the lightning network secured against hacking and double spends?

As I understand payment-channels, like the lightning network, they are working off chain (no record in the blockchain). The only record to the blockchain is the deposit transaction to open the payment-...
0
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2answers
110 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
99 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 ...
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2answers
605 views

How to securely store Bitcoin server-side?

I am working on a web application that needs to hold users Bitcoin for an extended amount of time (escrow-like scenario), and I was wondering what are some good steps/precautions and principles (dos &...
3
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1answer
60 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 ...
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3answers
392 views

How safe is it to use online wallets? [closed]

I want to know if it is safe to use online wallets? Can we trust online storages which stores our privkeys, passphase and wallet.dat files? I read that at least one android wallet was hacked so I ...