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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Searching through the blockchain

When a miner includes a transaction in a block, according to the integrity rules the miner should search for a previous transaction which output the coins being used in the current transaction. Now, ...
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Any need for coinbase field in coinbase transaction?

My understanding is that every block in the bitcoin blockchain has a coinbase transaction which contains a coinbase field. It is essentially an orphan field (placeholder) for use in claiming existing ...
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Problem with receiving bitcoins on my vps

I installed on my VPS (with debian 6) bitcoind v.0.8, then I generated a wallet for it: 12VWVmNEM1q6N9zMjX9aH3wSfRUbjVkZ21. Here is my transaction to this wallet, but when I'm looking for this wallet ...
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Will old accepted blocks ever be removed?

Or are they kept forever such that the chain from the Generation Block will always remain verifiable?
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Merged mining: are there any ways to prevent it?

Supporting merged mining allows a cryptocurrency A to improve the security its blockchain (increase the hash rate) by accepting work done on the blockchain of cryptocurrency B through insertion of a ...
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Location of blockchain locally on different platforms, and structure of blockchain file?

I just downloaded Bitcoin-QT, and torrented a snapshot of the block chain that is a couple weeks old. I put the bootstrap.dat in ~/Library/Application Support/Bitcoin and started up the app. Right now ...
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How to get last transactions made to a non-wallet bitcoin address?

I know I can rebuild my block index by setting txindex=1 in my bitcoin.conf file and restart bitcoind with -reindex so that I can view non-wallet transactions using: bitcoind getrawtransaction ...
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76 views

What parameters are used to calculate the challenge string during bitcoin mining (blockchain creation)?

How is the challenge string computed mathematically? What's preventing some node on the bitcoin network from broadcasting a challenge + proof to other nodes as it's own when it received it from some ...
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146 views

Trust Less Database Design?

I'm a young developer and have been following the bitcoin community for some time now and have wanted to contribute to a project. Have not fully read through the bitcoin protocol, but from my ...
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118 views

Does there exist a SPV-client in another language than Java?

The only (active) project I know that implements a full SPV client is BitcoinJ, which is in Java. Does somebody if there are any SPV implementations in other languages (like C) too?
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Bitcoind server strategy. How much disk space?

I need to host a Bitcoind on a VPS. My main issue is the disk space strategy. I don't know the amount of MB the blockchain adds per day or per month. On my disk I have 26GB of disk spent for the ...
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Download only first few blocks of blockchain

Is there an archive location or a place where I could be able to download only the first few hundred blocks of the block chain?
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Is access to mining the only obstacle to centralised bitcoin-like currency?

Considering the value of bitcoin beside dollars there seems to be so many applications where a centralised bitcoin-like system may be ideal for internal accountancy and transfers, especially among ...
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What's the formula giving the % of succesfully maliciously messing the blockchain?

With the recent (early 2014) GHash.io concerns about that particular mining pool getting too big, many people have talk about what a powerful miner could do if it wanted to "harm" bitcoin or ...
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How to make a block explorer (like blockchain.info)? [duplicate]

I've tried JSON-RPC, but it's very slow. What other things can you recommend?
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403 views

How to make a block explorer?

I need to make a block explorer for some alternative cryptocurrencies. I'm using Litecoin for testing, but JSON-RPC requests through PHP are very slow. Maybe JSON-RPC isn't the right thing for such ...
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Can blockchain size become a blocker for bitcoin adoption?

When I run bitcoin-qt, I noticed that it is taking lot of time to download recent blocks. It gives me impression that the more transactions, the bigger the blockchain. Even today the download is ...
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652 views

bitcoin-qt keeps on quitting with “failed to read block”

I just wanted to install bitcoin-qt on another machine (all others are working fine) but I cannot seem to retrieve the block chain using bitcoin-qt 0.8.6-beta (as downloaded from ...
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Detecting generation transactions

I'm implementing my own blockchain reader but I'm stuck validating transactions. I can validate a common transaction checking the UTXO and executing both scripts, but... how do I validate generation ...
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Why can't we make the Bitcoin software start the blockchain from the beginning?

I"m really wondering: you see 13 gigabytes (current blockchain size) is big enough only because there are all of transactions. Can Bitcoin developers create such a piece of code which will shrink the ...
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Old transactions in the blockchain

After a lot of reasearch on the net, I still can figure out if the following idea is relevant or not : I know (or at least I think I know) that each transaction consume all the bitcoins present at ...
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Is there any way to move the Blockchain? [duplicate]

I'm using a solid state for my boot drive, I'd like to make sure the blockchain goes to my data drive, any way to acomplish this? Edit: I am using easyminer and bitcoin-qt, it is about moving the ...
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59 views

Blockchain length by number of blocks or transactions?

It is my understanding that the longest blockchain is the one that should be used. Is "longest" measured by the number of blocks or the number of transactions?
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Chronologically sorting transactions within a block

Is there any way to chronologically sort transactions within a block?
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Sort order of transactions on blockchain.info

This list of transactions is supposed to be sorted by time, newest first: https://blockchain.info/address/1BWk7rcf4fRS6XHEDqVQPeeoZitGB65GYE?sort=1 However the transactions are not displayed in ...
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What is the bitcoind command to see how much btc a specific address has?

I was wondering if I can make a query via the console on how much btc a specific address has without having to go into blockchain.info. What is this command?
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Can Bitcoin-Qt be configured to trim the blockchain?

I run Bitcoin-Qt and Bitcoin Armory on a laptop. I don't have the space to store the whole 20 GB (or however big it is now) blockchain. I understand the need to run through the entire thing for ...
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Request blockchain for transactions

I have installed bitcoin-qt, so I maintain the blockchain locally. I have a list with transaction hashes strings (i.e f5d8ee39a430901c91a5917b9f2dc19d6d1a0e9cea205b009ca73dd04470b9a6) and I want to ...
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Do transactions reference the containing block of the previous transaction?

According to the wiki, it appears as if the previous transaction's index is referenced but not the block in which it's in. Why? How are transactions stored in the database that doesn't make ...
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How explicitly can the blockchain be pruned?

How can the blockchain be pruned? If the blockchain is tamper-proof thus cannot be changed, how can the data be removed? Please be as explicit as possible.
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As of today Jan-2014. How much drive space does the following coins blockchain data take?

As of today 2014-January-05. How much drive space does each of these coins take after downloading the complete blockchain? Bitcoin Litecoin PPCoin Florincoin Philosopher Stone Norbits Anonymous ...
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275 views

How do you configure windows to store the bitcoin blockchain data into another directory?

I'm currently on windows and was wondering how do you make the qt client download the blockchain data to another directory? Since my main drive is a SSD hard drive, I don't have much space to spare. ...
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Can an old block be inserted into the blockchain?

I've been shown how network time is enforced, but I'm still having trouble understanding how a false old block cannot be inserted into the blockchain with the entire chain remined or how a powerful ...
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Largest block (measured in Bitcoins)

What is the block in the blockchain with the most Bitcoins transacted?
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Block explorer with testnet raw hex data

Blockchain.info allows you to look at the raw hex of a transaction. But it doesn't have testnet functionality. Blockexplorer allows you to look at testnet, but I can't find a way to show the hex dump. ...
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Does Proof of Existence lose bitcoins?

http://www.proofofexistence.com/about -- "Use our service to anonymously and securely store an online distributed proof of existence for any document." The document is certified via embedding its ...
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How to decode very huge (!) raw transactions?

I'm parsing the blockchain to extract certain information I need for a script. One thing I do is parsing transactions. What I do is: getrawtransaction <tx> decoderawtransaction <rawtx> ...
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Block confirmation speed

Based upon any standard you think relevant, how quickly are current blocks being verified for rule-following such as correct balance tallies, true transactions, correct rewards & fees? Is this an ...
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How can the blockchain survive without an army or other kind of law enforcement?

I'm sold on most of the Bitcoin aspects. I believe that the blockchain has incredible potential value and how the fact that it's decentralized removes a lot of the corruption and cronyism that are ...
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Are transactions still tamper-proof if blocks are hashed without nonces?

If an alt were to forgo difficulty and timed release of new supply by removing the nonce from blocks therefore the whole difficulty/target system, is hashing without nonces still providing the same ...
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508 views

Move the blockchain to a different location

I am using the bitcoin qt app on ubuntu but the blockchain is very large and is wasting space on my ssd is there a way that I can move it to hdd. There doesn't seem to be a setting for this is it ...
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How does blockchain.info get it's info? Is it via the RPC interface for bitcoind or by reading the raw blockchain directly?

How does blockchain.info get their info? My intuition tells me that they have a modified client that reads and processes the blockchain (either directly from the network as it comes in or from the raw ...
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How to get a history of incoming and outgoing transactions for a certain address?

Along with the history of incoming and outgoing transactions, how would I find the first block that that address appeared in (to find when the wallet was created)? I want to do this by parsing with ...
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What would it take to track dollars like bitcoins?

Watching an ATM from a large US Bank accept a cash deposit makes me wonder - what would it take to track dollars like bitcoins? Said another way, what would a blockchain for fiat cash look like? ...
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When will the blockchain be pruned?

AT what stage will the blockchain be pruned? With more update of bitcoins the blockchain will start growing exponentially making downloading thereof impractical.
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Transactions are verified by miners. What happens when the last BTC has been mined?

Let's say we're X years in the future and we the last bitcoin has been minted. Since you can no longer incentivize mining new nodes of the blockchain, how will transactions continue to be verified?
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How does your account get credited when you send bitcoins(ex. Coinbase)

This question might have already been answered. If so, can someone send me the link to it. Let's say I create a blockchain wallet. It gives me a bitcoin address to deposit coins. Once I send bitcoins ...
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How can I view the Blockchain locally on my machine?

I'd like to view the blockchain on my Windows 7 machine. Right now I'm looking under roaming/Bitcoin/blocks, and trying to open blk00000.dat . I can't read any of it though, it seems the text is ...
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How do I lookup Blockchain sizes for crypto-currencies like Litecoin and Dogecoin?

I am new to mining cryptocurrencies. I am planning to set up a wallet for both Litecoin and Dogecoin. I am just curious on asking what are the current total blockchain sizes of both coins? This is to ...
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Can someone explain to me how do you read the blockchain.info transaction data?

Ok so i've been using bitcoin for some time now, but i never figured out how to read the blockchain.info transaction data. Here's a sample of what I mean: http://prntscr.com/2dj7tr --- ...