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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Can you help with Bitcoin block hashing algorithm ( PHP, C, Python, Javascript)? [closed]

can you help with Bitcoin block hashing algorithm ( PHP, C, Python, Javascript) ? I was working really hard to write block hashing algorithm in plain Javascript. Unfortunately the developed ...
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142 views

What is the difference between a wallet and paired keys? [duplicate]

So I've read that a wallet is basically a public address key paired with a private key. But is it more than that? Does the physical wallet file contain transaction and balance information as well ...
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Where are the blocks in the blockchain stored?

I understand that every transaction of bitcoin is stored in a "block" which is then added to the "blockchain". I realize that this is data of some sort that must have a physical location. Where is ...
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How can this input address have multiple values at the same time?

For the transaction: https://blockchain.info/tx/ee1658bb4d0de80a91d2e0005218d4cfab7c302a352458bd6afb6376b47fbf81 it looks like there are multiple inputs with different values for the same address. I ...
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1answer
239 views

safely delete the blockchain from .bitcoin directory

I have bitcoind installed and I'd like to free up space by deleting the blockchain from my .bitcoin directory. What set of files and directories should I delete such that the next time I start ...
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146 views

Is there a limit on number of transactions included in a block? [duplicate]

As per my understanding, every transaction is included in a block and the difficulty to find a block gets adjusted such that one block is found for every 10 minutes. Is it the case that all ...
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47 views

Why are the blocks out of order?

When I look at blockchain.info or blockexplorer.com, it shows the latest blocks. The most recent block, #283653, has time 2014-02-01 22:42:08. The previous block, #283652, has time 2014-02-01 ...
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230 views

Is it possible to know my ip address by simply connecting to the Bitcoin network?

It is saying that in order to stay anonymous, it is usefull to use Tor whenever connecting to the Bitcoin network. How does someone can discover my ip adress if I'm simply connecting to the bitcoin ...
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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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3answers
128 views

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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82 views

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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111 views

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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1answer
84 views

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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1answer
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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121 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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62 views

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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42 views

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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400 views

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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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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1answer
679 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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92 views

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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292 views

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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1answer
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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509 views

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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277 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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100 views

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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1answer
105 views

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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201 views

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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271 views

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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161 views

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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1answer
107 views

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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530 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 ...