Questions tagged [blockchain]

This tag should be used for questions pertaining to the blockchain. The blockchain is a list of all transactions that have occurred using the Bitcoin currency. It consists of blocks which are linked to each other, and each block consists of transactions. DON'T USE THIS FOR THE SERVICE NAMED 'blockchain.info'!

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Wallet forensic

Someone who scammed me used this wallet to receive the BTC 12fmomENb5SSxR54Bitua71CZrc4oVQtmB he hasn't moved them from there since July 31st I'm trying to figure it if that wallet belong to any ...
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248 views

How to decode a coinbase transaction?

Below is block result of block height 200,000 { 'hash':'000000000000034a7dedef4a161fa058a2d67a173a90155f3a2fe6fc132e0ebf', 'confirmations':396774, 'strippedsize':247533, 'size':247533, ...
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how to know miner of each bitcoin block [duplicate]

Do you know from what kind of API I can get miner info per each block? I've run bitcoin mainnet, and I want to know who mines each block if possbile. I've googled and read many docs but I couldn't ...
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What is the algorithm used to calculate profitability for Bitmain mining SHA-256 [duplicate]

I want to know how I can calculate the profit of bitcoin mining using SHA-256 Algorithm. I am interested in the formula that is used by calculators. For example lets say I have 700mh/s hashrate, ...
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3answers
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How is the monetary part of bitcoin stored?

How is the monetary aspect of a bitcoin stored? I understand that the blockchain is a set of records documenting transactions. I've also seen that blockchains in general can store arbitrary ...
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2answers
487 views

Pending transactions 0/3 [duplicate]

I sent bitcoin from my blockchain to my paxful and it says pending in my paxful history 0/3 confirm. Please what happened. And the bitcoin has left my blockchain wallet and it only showing unconfirmed ...
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4answers
116 views

How the blockchain knows that its been tampered with?

I know that the transactions stay in the block and hashed alongside few other things and that hash is stored in the next block. And I understand that if you try to tamper with one of the transactions, ...
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56 views

What is the program in Python that print information about the current block?

What is the program in Python that print information about the current block the world try to mine (I mean Version, Previous Block, Merkle Root, Time, Bits) plus how many zeros we are looking for for ...
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where can I get resource such as Blockchain technology in C++

I have found a lot of pdf files about Ethereum smart contract and JavaScript cryptocurrency. I still want to know about resources such as C++ cryptocurrency. Let me know about some good resources.
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Disable update of blocks locally with bitcoind cmdline option

I'm using blockchain2graph tool to import the Bitcoin blockchain into Neo4j. It uses JSONRPC calls to read block data. For this, I have to have the bitcoind service running. Is it possible to disable ...
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1answer
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Accidentally sent Blockchain BCH to Coinbase BTC? [duplicate]

I have made a mistake by sending cash bitcoin from Blockchain to Coinbase bitcoin address ( instead of Coinbase cash bitcoin address).. i want to retrieve the fund or send it back to my blockchain so ...
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1answer
51 views

Chain Race: How to know chain-length of competing chain?

If a fork happens, miners mine on the block they receive at first. Further, they only forward the block they received first (so the block they will use to mine)! So it can happen that 10% of the ...
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when does a transaction go through?

When exactly does the receiving party receives their payment. When the transaction is validated or when the transaction is added to a block?
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How would a bitcoin transaction fits into a double entry accounting

A bitcoin transaction may have multiple input and multiple output. When we have a multiple input and multiple output scenario. Also, we might not be able to identify from which address the transaction ...
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Bitcoin rpc testnet balance and transaction not visible

I'm using bitcoind-0.15.0.1 version & My Wallet Address is: muweVvHKnK1bE88pUsrpSAPuWry1V1AmHZ But whenever checking balance with following command: bitcoin-cli getreceivedbyaddress '...
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Sync with community delays

(Hello), I'm having some issues with Bitcoin Core, it is sync with community and the ETA suddently starts to increase. Now it shows 5 weeks, but it increases randomly. I think my internet connection ...
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1answer
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Why is 550 (MiB) chosen for minimum storage size for prune mode?

As you know Bitcoind can run in pruned mode, thus not advertising blocks to other nodes. Even though it has some drawbacks, saving you storage space isn't a benefit you can ignore. My question is ...
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55 views

Witness data storage localisation in the blockchain

Since segregated witness is in place inside Bitcoin blockchain, my understanding is that witness data are no longer stored inside the blocks, so if blocks are linked to each other where theirs ...
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Regarding 51% attacks in blockchain [duplicate]

Can anyone tell me, What is 51% attack in blockchain how this attack is prevented
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1answer
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When changing transaction data in a block change the hash of previous block?

If i only manually change the data on the block without touching/modifing the already calculated hash, then hash on the block its still valid because its already saved and was not touched ... so, ...
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26 views

Block validation process [duplicate]

Can some one explain how the block validation is done in blockchain based system with suitable example.
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can we make a blockchain that works like torrent?

Is it possible to make a blockchain system that allows you to download specific blocks from the blockchain instead of the whole blockchain? In my case for example, I only need 1 giga of the whole ...
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77 views

Creating a “listunspent” API call using MongoDB

I used a tutorial online to create my own block explorer (https://www.youtube.com/watch?v=laeV2slJgc8). In this tutorial, I used "Iquidus" to create the block explorer, which uses MongoDB and Node....
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1answer
50 views

How exactly does the network know if the miner has put forth a valid proof of work?

If all that the miner needs to do is find a hash with a certain number of leading 0's of the block's header, couldn't they just find a random hash with the required number of 0's that isn't ...
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1answer
39 views

Block validation in blockchain

if i am saying that node A is having some block (B) and other nodes X,Y,Z are wants to validate the block B than node A has to send the block B to nodes X,Y,Z. This block B contains the hash of ...
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1answer
42 views

Regarding block validation in blockchain

In mining process, miners validate the block based on proof of work or using some other consensus mechanism. Miners also validate the block. So in this validation process, miners validate only hash ...
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Does merkle root contain hashes of transactions from previous blocks?

Every block in a blockchain contains merkle root value. So for any block, there is some list of transactions and you create a merkle tree based on these transaction. For other blocks, same process ...
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1answer
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Transaction malleability

I have been reading about transaction malleability a lot still doesn't make sense to me. Is there a script I can use to test it out ? If the transaction that is malleable is changed by the attack, how ...
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1answer
73 views

Why is the 'Estimated BTC Transacted' referring to just one of the multiple outputs?

I recently started learning about bitcoins and came by this transaction. Here there are multiple outputs so if we consider one of them to be the change received by the sender then why is the '...
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2answers
53 views

What happens when the last added block in a blockchain is corrupted?

What happens when the last added block in a blockchain is corrupted? Is it still possible for the block to be accepted by a majority of the miners?
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1answer
106 views

How do block explorer sites show information that is not available on Bitcoin Core?

As I understood in the following post How to get unspents for a specified bitcoin address?, we should use listunspent only on addresses that belong to our own wallet otherwise will return blank. But ...
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50 views

Can't startup Bitgo on Windows [closed]

After installing bitgoJS, I cd into the bin directory and run the below command bitgo-express --debug --port 3080 --env test --bind localhost I got, 'bitgo-express' is not recognized as an internal ...
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1answer
109 views

Conditions for recovering a p2pkh bitcoin private key

Apart from Re-using same R value, What are the necessarily ecdsa values needed or method to recover the private key of a p2pkh address. When same address is reused numerous times to receive bitcoin ...
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1answer
61 views

Loading private key (missing bitcoin)

I exported the private key from a 0.7.2 because I could not how to upgrade the wallet. I then imported it into 0.18.0 I was expecting to see a balance and the transactions and nothing was found. I ...
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1answer
159 views

Error after reindex

Hello after I got an db error.. I try to reindex my db. But I got this error: ERROR: ReadBlockFromDisk: Errors in block header at FlatFilePos(nFile=75, nPos=117947311) So what can I do to fix it ? ...
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Is transaction verification called mining in blockchain? [duplicate]

A transaction in which A sends $10 to B; then this transaction is published in the network. Now, how the other nodes C and D will know, whether A is having $10 or not. and why A should reveal his ...
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Unknown command name and packet magic for bitcoin packets at the start of blockchain transactions

Recently I captured a part of blockchain when my bitcoin wallet started to syncing for the first time. I analyze about 10 Gb of traffic which was for primary transactions of bitcoin. wireshark can ...
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1answer
451 views

Does proof-of-work contribute directly to prevent double-spending?

I know similar questions have been asked before (e.g. How proof of work prevents double spend) but I'm struggling to visualise the solution to double-spending being directly reliant on proof of work. ...
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2answers
402 views

Is verification of a blockchain computationally cheaper than recreating it?

One of the advantages of cryptocurrencies like Bitcoin that is often repeated is how hard it should be to manipulate past transactions. The reason that is often stated is that you would have to re-...
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1answer
210 views

Bitcoin block headers download

i need all block headers hash (about 500k records), i tried to get from electrum wallet files, but when i convert the file to Ascii, it doesn't have full list. please help.
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1answer
50 views

I started build my own blockchain based on mastering bitcoin book using git on win7 and i have a problem

I started learning how to build a blockchain from Antonopoulos book using Git Bash and i have a problem. I used commands: git clone github.com/bitcoin/bitcoin.git cd bitcoin git tag git checkout v0....
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2answers
59 views

Including transactions in a block - rules and time / technical aspect

I’ve a question regarding block and transactions included in the next block that is solved. Let us assume theoretically that there is newly propagated solved block. And now there are: tx0 and tx1 –...
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175 views

Mining Probability

Assuming two miners have a (1/x) chance of finding a block over some time period, is the probability of both miners finding a block within that period simply (1/x^2)? More generally, would n miners ...
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1answer
40 views

Post Bitcoin mine reward: Lowering Difficulty an Option?

Maybe my understanding of blockchain, and Bitcoin need to be refined and will allow help me understand why my question wouldn't make sense in the grand scheme. But first Ill establish my core ...
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1answer
61 views

Who is a first miner that receive a transaction from end-user?

This is a First Question. As you already know, the blockchain like Bitcoin, Ethereum is a software program based on peer to peer network system. so I am wondering that who is a first miner that ...
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1answer
50 views

Timer-based consensus algorithm in blockchain

Assume that there is an algorithm that ensures: 1- That a full node chooses an honest random wait time. 2- That the same node has waited the specified amount of time before proceeding to mine a block. ...
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1answer
34 views

How public-key cryptography secures bitcoin transactions from 51% attacks and Mining Attacks

I wanted to better understand how public-key cryptography avoids 51% attacks and mining attacks, also if this question is wrong please correct so that i can improve my research and provide me with ...
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1answer
56 views

How can a 51% attack be successful? [duplicate]

In the paper by Nakamoto, miner can accept the mined block only if all transaction are valid. Assume that there are 5 miners in the world. 4 of 5 are honest that have 10% of 100% hash power and 1 of ...
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18 views

The time when the miner get a new block [duplicate]

I am wondering the time when get a reward for new mined block. Theoretically, miner will earn reward when they mine new block. but at that time, there is no way to verify that they really waste hash ...
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26 views

About the balance of specific address

I have a question about how to figure out balance of specific address in the Bitcoin. There are many node in the blockchain(total # of nodes are 10000 based on 01/16/2019). but some nodes may have ...

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