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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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49 views

Is it possible to deploy a python script on Ethereum Virtual Network or NEO?

Is it possible to deploy a python script as a dApp on the Ethereum or NEO virtual network?
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1answer
31 views

Creation and Distribution of a New Block

Given that a block is collection of transactions that a miner can accumulate in 10 minutes, could it not be the case that every miner gets to work on one's own block? Delays in the network imply that ...
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1answer
30 views

What good is to store all the transactions in the history

Bitcoin stores all the transactions that happened in the blockchain. Are really all the transactions needed? What good is it to have transactions ten years old stored. Isn't it a waste of discspace?
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2answers
34 views

How output transaction works in Bitcoin?

Click here for reference. Note also that an output can be used only once. That's why there's a concept of "change address" in the bitcoin ecosystem: if an output of 10 BTC is available for me to ...
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1answer
39 views

in the white paper you have 2 sides : attacker and honest node

What does it mean that there is either the attacker or honest node. This means that within 10 minutes either attacker or honest node mines a block but what about neither OR another side ? How could ...
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1answer
35 views

what does it mean to have >51% hashing power for mining a block? [duplicate]

Can someone please shine some light on this and how it links to the analogy between honest node and attacker ? also can attacker start mining 2 blocks ahead ? or 3 or 4 blocks ahead ? In the white ...
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1answer
40 views

Why is the output address a list in RPC/console?

Vout contains a list of addresses, which I noticed to be always with size = 1, if it exists. The following is an example from Bitcoin Testnet: { "value": 0.91840581, "n": 2, "...
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0answers
26 views

jsonRPCClient bitcoin not generating transaction id however new address is generated

I'm using jsonRPClient to connect to my, I'm able to generate new wallet address using getnewaddress however when i make a transfer using sendtoaddress transaction id is not generated. sendtoaddress ...
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1answer
44 views

Why is my blockchain.com not receiving bitcoin?

I created a wallet on blockchain.com, copied the address from the '' bictoin request '', sent it to the person, and that person sent me a bitcoin after a few hours. After a few hours my laptop ...
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2answers
59 views

How do wallets receive the amount of Bitcoins

I've always wondered how wallet clients can receive the corresponding amount of Bitcoins so fast. If I want to know how muc Bitcoins I own, I have to parse the complete the complete blockchain to ...
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1answer
15 views

Are smalltime block chains susceptible to brute force liars?

My understanding is that the integrity of the bitcoin block chain is dependent on the consensus of the masses - that no single actor can write entries at will unless they. controlled over 50% of the ...
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1answer
268 views

How do I concatenate two hashes in Python?

Concatenating and double SHA-256 hashing "a751efbeabe73bdf9d08df5760104feff915d9d807d4c62178cdeb98d8c25f43" with itself "a751efbeabe73bdf9d08df5760104feff915d9d807d4c62178cdeb98d8c25f43" should ...
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1answer
44 views

How do I get imported Bitcoin in my blockchain wallet without having to pay more for the private key?

ich habe Geld investiert anscheinend bei Betrügern, dass lief Alles über Facebook Messenger , ich habe ein Blockchain Wallet erstellt und dummerweise Wallet ID und Passwort rausgegeben, als es um die ...
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0answers
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Private Blockchains: Potential rudimentary distributed cryptographic filesystem?

I have seen examples of people using public blockchains to store data of all types, everything from basic text to photos and music, encoded into fake addresses. This got me thinking.. about a ...
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1answer
36 views

How would you recommend parsing a private bitcoin core node with nodeJS?

I just need to parse a private node and lookup one bitcoin address and get all transactions going in or out of the address preferably using nodeJS within the last 200 or so blocks. Any recommendations?...
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2answers
105 views

Why choose the longest chain before checking for double-spending?

Can we make the following changes to the current POW protocol to better avoid double-spending: a) For full/mining nodes that receive two chains, check if there are identical addresses that occur on ...
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0answers
18 views

How would get a list of transactions associated with an address from private node? [duplicate]

I am running a private BTC node and am trying to get a list of every transaction given an address between block x and block y. So pretending my wallet address is AbCdEfGh it would return a list of ...
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2answers
47 views

Blockchain validation process is linear?

I've read at a few places that the nodes validate transactions in a linear fashion, i.e. after node A validates, then node B, etc. (which is also the reason, as claimed by many, why blockchain suffers ...
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1answer
57 views

how to retrieve BTC from BCH address

I was on KuCoin and accidentally sent BTC to the BCH address (thinking I was buying BCH). Of course nothing shows in the BCH wallet on KuCoin. I can see it on the blackchain but cannot access it.
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2answers
40 views

Detecting Wash Sales/Transactions

I run a site which is essentially an e-commerce platform where buyers connect with sellers and all transactions happen in Bitcoin. I worry about sellers on the site continuously buying their own items ...
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2answers
75 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 ...
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1answer
382 views

How to send bitcoins without the bitcoin client in PHP

Is there a way to send bitcoins programmatically without the bitcoin client using PHP?
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2answers
102 views

Bitcoin Transaction using API with Custom Fees

I want to transfer Bitcoin from one individual address to another using API. But I want to set Transaction fees as per my requirement. So How can I do it ? Right now I am using blockchain-transaction ...
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1answer
311 views

Unspent/Spent Flag in Blockchain

I just started getting interested in the blockchain a week ago, however there is something I can not just figure out. Regarding the flag "Spent/Unspent" in transactions. I get that we flag "spent" ...
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1answer
41 views

Hardware-dependent block difficulty?

Is it possible to make block production difficulty not the same for every node, but automatically adjusting to the node's hardware speed? For example, node A and node B are both trying to solve for ...
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0answers
29 views

How to Setup Masternode for Beginners? [closed]

guide is for a single masternode, on a Ubuntu 16.04 64bit server (VPS) running headless and will be controlled from the wallet on your local computer (Control wallet)
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1answer
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Unable to send total amount of bitcoin even after deducting the transaction fee what do I do? [closed]

Hi I recently imported a wallet to blockchain wallet from a backup, the wallet and everything shows up and everything but since the imported wallet is not protected by the backup phrase and not as ...
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2answers
81 views

How effective are arbitrage bots? [closed]

I hear many good reviews about cryptobots. But they all work according to the pattern. Explain to me how to use them correctly?
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0answers
23 views

Can we decide where the data should be stored on the blockchain in Stellar?

Due to the GDPR rules, we know that the data of all the users in EU should stay in EU. How do we know whether the data of the users using Stellar is being stored in EU? Can we have a permissioned node ...
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4answers
53 views

How do I connect my online store to the blockchain?

I have an online store for which I want to be able to accept bitcoin. I believe that what I need is an API that will connect my store to the blockchain. If not, the question below would relate to ...
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0answers
43 views

How to deploy BTC blockchain on my Ubuntu17 VPS

I would like to setup Bitcoin nodes on my VPS so we can call balance API unlimited time. Actually we are launching ICO for that we are in need of this we have previously deployed ETH and NEO node on ...
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2answers
63 views

How to setup Masternode from Beginners? [closed]

I need a guide for single masternode, on an Ubuntu 16.04 64bit server (VPS) running headless and will be controlled from the wallet on your local computer (the Control wallet). Thanks
0
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1answer
52 views

Is altering Blockchain Wallet possible even after all the securities?

A man named James Bryan posted an investment plan and took BTC from me. On the day of payout, he asked me to simply fund my Blockchain wallet to receive the money. The minute I fund the wallet, he ...
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1answer
37 views

Bitcoin RPC Call [closed]

I want to monitoring 3000 address continuously for BTC. So I am using third party API for get BTC balance. but all API has limitations for access. Can I get an API reference where I can call API ...
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0answers
26 views

Are there any blockchain implementations that are not based on the Bitcoin source code?

I wanted to code up a blockchain from scratch using C++. So I got around to looking at some existing blockchain source code to get some ideas. But all I can find is the Bitcoin source or forks of it. ...
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0answers
25 views

How to prevent 51% attack on newly created coin [duplicate]

I am interested how bitcoin managed to prevent 51% attack in the beginning? I am about to create my own coin and i want miners to mine blocks. but The problem is I am afraid  51% attack might destroy ...
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0answers
27 views

how to keep private data on private blockchain?

I have a data like this {'user_id' : 'abc', 'game_id' : '123', 'team' : ['a','b','c'], 'pool_id': '1001'} I want to store the above data in a private blockchain so that people can see. ...
3
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2answers
106 views

Why we need mining?

I know is related to these: What is the rationale behind Bitcoin mining? Why do we need Proof of Work in bitcoin? But I don't fully understand those answers, and I think usually is much easier to ...
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0answers
123 views

Practical Implementation of Liquidity Provider for Crypto Exchange

I understood about the basics of the liquidity provider ,but I wanted to know about what are the ways to provide the liquidity provider for my exchange. Do I need to practically implement it? How can ...
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2answers
85 views

Bitcoin New Block Event Trigger

I want to know when a new block is discovered, I am watching debug.log to see if it has changed, I know there is a new block if the line contains "UpdateTip: new best". Is there a better way to do ...
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1answer
90 views

How to get Coinbase Text for newly found block

Websites like blockchain.info and btc.com give Relayed By information to find who found the block. I can see coinbase text in the website https://coin.dance/blocks. Is it possible to get that ...
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1answer
29 views

How many change outputs are there in a Bitcoin transaction

I have been reading the following article: https://coinmetrics.io/difficulty-estimating-chain-transaction-volume/ It mainly discusses how unreliable transaction volume on a UTXO blockchain such as ...
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2answers
69 views

Providing Liquidity in CryptoCurrency Exchange!

Can anybody give some idea about the issue of providing liquidity to the users for creating a cryptocurrency exchange ? Thanks!
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0answers
22 views

How to verify the response of getblocks?

Sorry that this question might be weird since I'm a beginner in blockchain tech. As I know, to download block data, a node first sends getblocks to its peer node, and the peer node send upto 500 ...
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2answers
432 views

hash dosent match nbits

Im trying to clone a coin and I created a genesis block but when I run the wallet, it dosent start.. When I go to the log file, I see this error and I honestly dont know how to solve the problem. How ...
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2answers
69 views

Is there an efficient way to get the last 200 blocks (BTC, LTC, ETH)?

I am looking for an efficient way of getting the last 200 blocks and being able to pull all transactions related to an address. I would like to do this for BTC, ETH, and LTC. Is there any way to ...
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3answers
3k views

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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0answers
72 views

Bitcoin-cli access - how do I access it?

newbie question here. I am trying to learn to interact with the Bitcoin blockchain and I want to use the native SCRIPT language. I already downloaded the entire node and synced on an AWS Linux ...
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1answer
48 views

Transaction Confirmation between Users

I'm reading this paper [1] that explain what happens when a user B wants to send money to the user A. The example says: When the miner finds a hash value with the correct number of zeros (i.e., ...
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1answer
45 views

On a low level, how are long chains kept secret and later broadcast during 51% attacks?

I've been reading about the vulnerabilities of PoW crypto, and there's a part of it that I don't understand. Suppose I wanted to stage a 51% attack on Bitcoin (not really feasible, but bear with me). ...