The blockchain is a list of all transactions that have occurred using the Bitcoin currency. Please don't use this tag for the service named 'blockchain.info'.

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How to generate a private key to create wallet through api in Block chain

I need to pass private key while creating a wallet in blockchain.info through api call which is defined here https://blockchain.info/api/create_wallet I'm using php for creating wallets. Please ...
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What is the estimated size of complete blockchain when all bitcoins are mined. i.e around 2140?

By size, I mean how many GBs or TBs of data storage I would need to save entire blockchain starting from Genesis block when all bitcoins are mined?
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How to store blockchain data

If I wanted to imprint the blockchain data on a database, with the purpose of performing complex or just different than the RPC-based queries, how would I do it? Would I have to go for a relational ...
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blockchain.info and blockexplorer.com show different balance for the same address

Does blockexplorer.com have a bug or some other reason? https://blockexplorer.com/q/getreceivedbyaddress/1KWd23GZ4BmTMo9zcsUZXpWP4M8hmxZwRU 1.95331249 ...
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Blockchain (lack of backwards) compatibility in Bitcoincore 0.10.x

From Bitcoincore release notes: Because release 0.10.0 makes use of headers-first synchronization and parallel block download (see further), the block files and databases are not ...
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Blockchain.info RPC API and deposit/withdraw problem

I'm using blockchain.info RPC to detect deposits using Node.JS as server, using listTransactions method. Because blockchain.info doesn't has walletnotify api. When processing deposits, there is no ...
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If bitcoin fails as a currency, how will blockchain tech still be secure for other applications?

We often hear proponents, like Andreas Antonopoulos, say things along the lines of Bitcoin being an application of the Blockchain technology and that Bitcoin as a currency can fail, but blockchain ...
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What do people mean by solving bitcoin transactions? [duplicate]

I have been looking at a lot of posts about how bitcoins are generated. They keep talking about how miners do computations of other "transactions". Do they mean bitcoin transactions or other forms of ...
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How to generate a Litecoin Private key and correspondent Public Address in C#

I found this C# tool to generate addresses for Bitcoin (compressed and uncompressed): https://en.bitcoin.it/wiki/Bitcoin_Address_Utility https://github.com/casascius/Bitcoin-Address-Utility It ...
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How is UTXO tracked?

What is the best way to compute UTXO of any address? Do I have to traverse whole block chain each time? Is there a efficient way to compute it?
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Verifying Bitcoin ownership

Suppose Alice has 30 bitcoins from David. Now Alice wants to transfer amount 20 bitcoins to Bob. Now, Alice creates a transaction with Bob's bitcoin address. To prove authenticity and integrity, ...
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How is the whitepaper decoded from the blockchain (Tx with ~1000x m of n multisig outputs)

The whitepaper is apparently encoded at 54e48e5f5c656b26c3bca14a8c95aa583d07ebe84dde3b7dd4a78f4e4186e713, which is an m of n multisig Tx with 947 outputs (just under the scriptsig limit of 20kB!). ...
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How do I compose a transaction with OP_RETURN in Python?

Currently trying to figure out how to use Python to construct a transaction with OP_RETURN. I tried to encode the message myself, and had no luck. I found a function, OPReturn(), on the internet, but ...
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Non standard Tx with obscure OP codes: examples

I've been writing Python code to fetch various transactions and came across this: 77822fd6663c665104119cb7635352756dfc50da76a92d417ec1a12c518fad69. The script field is as follows: scriptPubKey: ...
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Bitcoind stuck loading blockchain after -reindex -rescan

I am running bitcoind on EC2. I did portforward 8333 and tried -reindex -rescan. My debug.log shows 2015-02-08 20:02:19 ProcessBlock: ACCEPTED 2015-02-08 20:02:19 ProcessBlock: ACCEPTED 2015-02-08 ...
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1answer
25 views

blockchain webgame - use api or actual blockchain to build database?

I am currently designing a blockchain based web game, and part of the game is to display data from the blockchain in table format on the site. The data will be updated peroidically, or in short ...
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Blockchain MySql Implementation - Updating Database

I know there are similar posts here about utilizing MySQL as the basis for an application which contains the contents of the blockchain, but i have not seen any on-point answers to the issue of ...
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How does merged mining work on a technical level?

In bitcoin, miners hash header twice with the SHA256 function. This header is consist of the below fields, as described by this question. version previousHashBlock merkleRoot time difficulty nonce ...
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Book question on Bitcoin [duplicate]

I was wondering if you have any books in order to understand more in depth both Blockchain technology and Mining
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How to find Z value of multisig transaction?

for example this transaction: http://2coin.org/txinfo.aspx?txid=6c3dc603da32bba3f56f2b33053aaf0f0f17322386c0c6846786bffe49f6ef22&cur=BTC Script not of right size to be a scriptSig, expecting 2 ...
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Is there a fixed order for all transactions in the block chain?

Every block in the block chain contains a list of transactions. This list has a certain order which is basically set by the miner introducing the block. The merkle root in the block header requires ...
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Bitcoin spend before received

When browsing the Blockchain I came across this address. It seemed peculiar to me, that the amount of 0.6 BTCs has allegedly been spend before received. Is it because the "receiving transaction" ...
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What is a block?

I know bitcoin has a block chain that is from my best representation a list of blocks. I know the block holds many transactions. But i'm still very much lost as to what a block is and how a block can ...
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Bitcoin-QT blockchain: your speed experience with using any HDD connected via USB2.0 with TrueCrypt?

Background (I've never used bitcoin before.) I have Bitcoin-QT 0.9.3 (zip version). bitcoin-qt.exe sits on the internal HDD of my laptop. All of the other stuff (blockchain, wallet,...) on a 128GB ...
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How is it that concurrent miners do not subvert each other's work?

Every time a new block is added on top of block chain, the miners have to restart their work because the next block has to have a proper reference to previous block. Let's suppose that there is some ...
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Is it necessary for all miner to reset minig when the tip of blockchain has chenged?

Each block in blockchain contains a pointer to previous block (block header). If multiple blocks reference certain block as their parent, only the one that is part of longest chain is accepted. ...
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How do text, scripts, and other information get embedded inside the blockchain?

Someone recently suggested that scripts could get embedded inside the blockchain and executed independently by designated machines. What exactly can get stored inside the blockchain, and what are the ...
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Why doesn't bitcoin place additional constraints on competing block chain forks, other than length of chain? (e.g., time and confirmation count)

In Bitcoin's proof-of-work system, consensus on which chain of blocks should be considered the "true" block chain is based only(?) on which chain is longer. Accordingly, to quote a nicely written ...
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Can private keys remain offline for their entire life?

I am new to Bitcoin and this question is based on 3 assumptions that may be incorrect. Assumption 1: If I understand correctly, the Bitcoin address is generated algorithmically independent of the ...
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1answer
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Is it chain of headers rather than a chain of blocks?

We know widely used explanation of the blockchain: "Every block contains a hash of the previous block". The sentence above implies that since every block contains a hash of the previous block, ...
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1answer
84 views

How to download blk.dat files from a specific block number?

I want to download blk.dat of a specific block number, How can I do this ? Note: I'm only interested in specific blocks, I only want to download blocks for example that are numbered between 100 and ...
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Why use OP_RETURN for long-term timestamping if they are pruneable?

There are some timestamping services such as proofofxistence.com that use OP_RETURNS transactions to store a document's hash, so in the future a 3rd party can verify the existence of the hash (and the ...
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What restrictions does merged mining place on the sidechain?

What restrictions are imposed by merged mining on the structure or functionality of a side chain (besides it having to use the same PoW schema)? For example, could the side chain have a higher block ...
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Is the block timestamp reliable enough to timestamp the hash of a document?

In using the blockchain to timestamp the hash of a document, so to prove that it existed before a certain time. Is it reliable? Do you think it can stand on court? (IANAL and probably you neither) ...
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How many transaction and btc have been cancelled?

How many btc have been transferred in orphan blocks, but then never included in any later block? How many btc have been transferred in zero-confirmation transactions that have never been included in ...
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Filter transactions per block 50 BTC or Higher

I'm using the blocktrail python api, to try and display transactions above 50 BTC per block for a visualization project. I think I'm almost there but can anyone help me understand where I'm stuck? ...
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What if some group of people start sending small transactions from wallet to wallet just to make the blockchain bigger?

What if some government start using their computers to move the tiniest amount of Bitcoin possible, from wallet to wallet, just to make the blockchain REALLY big? Is this possible? And also, is it ...
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How often does a block have only one transaction?

I was looking at blocks on blockchain.info, and came across this one with only one transaction in it: (the mining reward one) ...
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Help me understand Bitcoin analytics [closed]

I'm trying to use the Blocktrail API to look at the oldest Bitcoin addresses to create a info graph piece - besides looking at historical transactions, what else would be good for me to analyze? \\ ...
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Armory can't find blockchain files produced by bitcoin-qt

Armory is telling me to restart the application using --satoshi-datadir=[path] But I don't understand how to do this? I'm running MacOSX. I know where the blockchain is. How do I start Armory with ...
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Lower confirmation time schemes: any requirement between confirmation time and the probability to find a block during that confirmation time?

Bitcoin, the first blockchain-based cryptocurrency, set a 10 minute confirmation interval time; LiteCoin set a 2 minute confirmation interval time; DogeCoin set it at 1 minute; QuarkCoin set it at 30 ...
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Safely interrupt -reindex?

My database became corrupted and I had to reindex: bitcoind --daemon -reindex It takes my computer quite some time and CPU power. It's been running for an hour but it will take at least 4 more ...
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42 views

My balance gets sent back to me [duplicate]

I'm using the blockchain API to make a "send to many transaction". In the recipients I only put other people addresses, but somehow the API sends the remainder of my balance back to me. For example: ...
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Query Blockchain: Reference previous transaction in “txin”

I'm currently working with a postgresql database I've downloaded here which has the following schema and has probably been parsed using Bitcoin-ABE (I added some indexes and redundant columns): Now ...
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1answer
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What happens to off chain transactions when the blockchain is reorganised?

Many companies seem to use off chain transactions to transfer bitcoins between their own customers. What happens when a side chain gains dominance and no longer contains a block with the underlying ...
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1answer
75 views

Bitcoin 101, need some knowledge [closed]

I am new to bitcoin. How do I check if my blockchain is working? I have tested some free bitcoin sites but neither of them have worked.
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How to fork an Altcoin Which has 0 Reward Block to continue mining after the LAST POW BLOCK

Im trying to learn how is it possible to Hard Fork an Altcoin Blockchain to Continue the Mining Phase after the LAST POW BLOCK. The Block Reward is already 0 and the LAST POW stops at Block 8000. And ...
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Double Spending - Does each node maintain a list of unspent transaction references?

My Understanding Of How Bitcoin Prevents Double Spending Each transaction contains references to the input transactions and ever node has to verify all transactions from time immemorial to ensure ...
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Querying insight-api to dump all addresses with a positive balance

It's been some time I've been using 'insight-api' (https://github.com/bitpay/insight-api) and I couldn't find any documentation / anything helpful to query leveldb in a way that all addresses with a ...
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What methods are currently used to embed additional data into the Bitcoin blockchain?

Yes, I do understand that it is inappropriate to pollute the already large blockchain with data not necessary to make the currency work. But I know people are using Bitcoin as an underlying system for ...