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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36 views

Why do some outputs have a zero value and no address?

What does it mean when an output has a value of zero and no address? I'm looking at some fairly recent transactions, and I don't understand what this means. Here's an example: ...
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0answers
15 views

What happens when the Block Reward of a Currency is Changed to a Greater Value? [duplicate]

What Happens if the Reward for block solving is changed to a very great extent and if most / all of the users update to that version with the edit.. For example if block reward is 12 x and it is ...
2
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2answers
65 views

How does “headers first” effect BLKxxxx.dat structure?

Assuming a full node running Bitcoincore v0.10 (with txindex=1), how exactly does the new "headers first" functionality affect the structure of the blockchain data? (Specifically, the blkxxxx.dat ...
2
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1answer
34 views

Bitcoin transactions over Ripple Network

I am interested in using the ripple network in conjunction with bitcoin transactions, but am curious as to interplay between the ripple ledger verification and the bitcoin blockchain verification. I ...
0
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2answers
31 views

Can coin wallets create their own network/blockchain?

In other words, I want a coin with NO premine and NO mining. Can the wallet, alone, generate the coin(s) and the blockchain, based solely on inter-wallet communication (establishing a wallet ...
4
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2answers
66 views

Is there a special name for the block currently at the head of the chain?

Just as we have the genesis block which is block 0, is there a special name for the block currently at the head of the chain? Obviously such a block would be observer dependent and never absolute but ...
1
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1answer
45 views

Blockchain parser for transaction level details

I'm looking for transaction level data for both inputs and outputs. The znort block parser returns the type of data I'm looking for, however it doesn't seem to detect multisig transactions. Has anyone ...
0
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2answers
61 views

Create alternative blockchain with proof-of-work

For learning purposes, I want to create an alternative special-purpose blockchain. It would use a proof-of-work function that is different than the one in Bitcoin. Short of forking bitcoin and going ...
2
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0answers
26 views

What is the minimal block time practically possible? [duplicate]

There have been so many altcoins that experimented with parameters like block-time, and I was wondering what turned out to be the minimal feasible time? If its 10 seconds for example, there will be ...
3
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1answer
59 views

Live Blockchain Backup

What is a good strategy for backing up bitcoind's blockchain files (not its wallet file) without having to take (e.g.) a bitcoind that is powering a counterparty-server instance offline? Copying the ...
0
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0answers
47 views

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 ...
1
vote
2answers
137 views

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?
0
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1answer
60 views

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 ...
3
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1answer
57 views

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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0answers
29 views

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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0answers
34 views

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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4answers
127 views

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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0answers
18 views

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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2answers
48 views

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 ...
0
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1answer
26 views

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?
2
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1answer
59 views

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, ...
12
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1answer
2k views

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!). ...
1
vote
1answer
120 views

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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2answers
98 views

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: ...
0
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1answer
182 views

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 ...
0
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1answer
34 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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1answer
86 views

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 ...
7
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1answer
94 views

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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0answers
7 views

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
0
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1answer
95 views

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 ...
3
votes
1answer
58 views

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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vote
2answers
176 views

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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1answer
78 views

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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0answers
42 views

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 ...
3
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2answers
519 views

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 ...
1
vote
1answer
42 views

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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1answer
60 views

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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3answers
336 views

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 ...
13
votes
1answer
1k views

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 ...
3
votes
1answer
58 views

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, ...
2
votes
1answer
100 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 ...
0
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2answers
52 views

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 ...
2
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0answers
35 views

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 ...
0
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1answer
66 views

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) ...
3
votes
1answer
98 views

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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0answers
53 views

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? ...
6
votes
1answer
151 views

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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2answers
167 views

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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2answers
89 views

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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0answers
43 views

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 ...