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 switch the method of blockchain download?

I torrented bootstrap.dat and used am using it to populate the blockchain. It is close to being complete, but my server has ran out of room. There is room for one copy but not enough for two. Is it ...
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What are the equations to convert between bits and difficulty?

If we take transaction hash 0000000000000006770c3806960539ca83a24facbd99ea212f37f2a0e6a5629a for example. The difficulty as a 32 bit float is 50810339.04827648. The difficulty in bits as an unsigned ...
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Best way to anonymize bitcoin transactions?

https://en.bitcoin.it/wiki/Mixing_service How do sites like this work? "Mixing services". I know it can be broken and traced back with coinsuduko but how exactly does it wash your coins. I doubt they ...
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What would happen if a portion of the Bitcoin network was separated from the rest of the network?

Yesterday I asked a question over at SuperUser, so that I could have my facts straight before asking this question. The scenario sets the basis for this question. Regarding bitcoin, what would ...
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What are checkpoints?

I often read that checkpoints protect the network from a 51% attack because an attacker cannot reverse transactions made before the last checkpoint. How exactly does this checkpoint mechanism work? ...
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Strange transaction (block 71036)

What happened to this transaction? Can someone explain it? http://blockexplorer.com/t/9eHTFRi3Qq
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Where to place Bitcoin bootstrap.dat

I'm sure this has been asked many times before, but I've recently gotten into the whole cryptocurrency thing starting with Dogecoin, and I now want to use Bitcoin as well. I am on Windows 7. I found ...
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2answers
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How to get correct block details url with block height on blockchain.info

I need to generate urls to block details page of blockchain.info when I have block height as input but cant find the relationship between block height and the number they are using in the url. Eg: ...
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How does a client decide which is the longest block chain if there is a fork?

Is it only the block height or is it the effort that went into the forks? In other words: does this decision account for different difficulties?
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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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243 views

Bitcoins Stuck?

This morning I attempted to send BTC to my Bter account from my Mt Gox account. I sent them and they seemed to reappear. I sent them again and there was a little left over, I sent that. Now the ...
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Can I use Blockchain API to get number of transactions at BTC address?

When I go to blockchain to look at a BTC address I can see a count of the number of transactions that have been sent to that address. So can I use the blockchain API to get this information? I have ...
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146 views

Wouldn't compromised crypto require entire block chain to be recomputed?

If one of the cryptographic building blocks of Bitcoin were to be broken, couldn't that result in the entire block chain needing to be recomputed? And how would that work, given the computational ...
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Possible to use BlockChain.info and Bitcoin-QT synced?

I've used both BlockChain.info and Bitcoin-QT. Is it possible to use the same addresses on both? I don't have a incredibly large amount of bitcoins, so I'm not worried about it getting hacked into, ...
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165 views

How can I search for transaction text on the blockchain?

Is there a google like search engine which can search for any text that is included with a bitcoin transaction? As I understand it each transaction includes 80 characters of text as well. Update It ...
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2answers
1k views

How to move the blockchain data while still being able to use the wallet?

Using the standard client, Bitcoin-Qt, v0.8.1: I would like to move the blockchain data from its default location to a different location (maybe even an external disk or NAS drive). What should I do ...
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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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Accelerated block generation

According to http://btc.blockr.io/ : Height Block created Transactions Block fee Size (kb) Days destroyed 318525 2 minutes ago 28 0.00370000 8.36 kB 2.00 318524 3 ...
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If a block chain is considered invalid, how about transactions in this block chain?

Say if at current time there exist split of block chain, we call them A and B. A is "longer" then B, as the result B will be eventually forgotten, but what happened about the transactions in blocks on ...
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json RPC Blockchain not Working

I am unable to connect to the Blockchain API, here is the code: $rpc_host = 'rpc.blockchain.info';$rpc_port = '80'; $rpc_user = 'XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX'; $rpc_pass = 'PASSWORD'; ...
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141 views

Blockchain API support - receive payment IPN

I'm having some real trouble setting up the Blockchain API on my server First off is it possible to test it offline with local host? Secondly, how do I set it up so when a tx is made through my ...
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Bitcoind randomly stops downloading the blockchain

I have bitcoind running from a 2 GB CentOS 6 box in order to check balances of addresses. The problem is that it just randomly stops downloading the blockchain sometimes, and I have to use ./bitcoind ...
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2k views

Stuck downloading block chain

I haven't started/used my Bitcoin client for ages but now whenever I start the client it is downloading block 135407 and it does not progress past it. What can I do?
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If more than one coin did the “mini-blockchain” proposal, would that make the weaker coin vulnerable?

So, I was reading this paper as a proposal to the ever growing blockchain problem. In summary, it's security is provided without a full blockchain by having a proof chain with these fields: Previous ...
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Armory client shows transaction unconfirmed

I am new to btc and am using the Armory client. Yesterday I transferred some btc to wallet from my MtGox account. The wallet showed the btc received within minutes, but, after 12 hours it still shows ...
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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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list of blocks as text file [duplicate]

Is there a reliable source where I can download the blockchain as a text file? Or perhaps is it included in my bitcoin-qt folder after it synchronizes with the network?
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Blockchain growth projections and risks

What is the projected block chain growth over time and could an attack on Bitcoin be lauched that creating an enourmous number of micro-transations to fracture the currency (e.g. spamming the system ...
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255 views

How do I scan my bitcoin receipt into my wallet?

I bought Bitcoins from the Robocoin ATM (I'm told it's the only one) and it gave me a receipt with a QR code to scan into my wallet. I downloaded Blockchain, but don't see where in the app I can scan ...
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pending payment

Three days ago I sent a payment via my MultiBit wallet but it is still marked as unconfirmed, only 4 confirmations. How long it will take this transaction to become fully confirmed? Thanks.
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How many OP_RETURN transactions in the Blockchain would be too many?

I realize this question may not have an answer and therefore might not be suitable for SE, but I'm very curious about OP_RETURN transactions. OP_RETURN transactions appear to be the accepted ...
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108 views

Retrieving all the funds from BIP32 derived wallets

An ecommerce site is using BIP32 wallets for receiving order payments from a tree of child keys where each leaf node is unique to one purchase transaction. Is it common for the site to immediately ...
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3answers
318 views

How to get current BTC rate for BRL(real) using php cURL or javascript

Is there anyway to get current rate of BRL = BTC. I saw the blockchiain ticker. But the value for BRL currency is not updated As listed here in preev. I want to get the current 1BTC= how much BRL ...
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Overview of Blockchain 2.0 smart contracts for the layman?

I have a pretty good understanding of how the Blockchain secures data using hashed inputs of the previous block and being secured by the P2P distributed network. What I'm interested in is a layman ...
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Can I force the Bitcoin core client to keep the blockchain on another drive instead of AppData/Roaming? [duplicate]

I have been profiling my disk space and found that the blockchain has become pretty big 25GB or so. I would like to force the core client to save the chain on another drive that is much larger. Is ...
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getrawtransaction doesn't work for every transaction with -txindex=1?

i put txindex=1 in bitcoin config and reindex blockchain after that when i call getrawtransaction for some transactions didn't exist in my wallet and work well like: [Working] getrawtransaction ...
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How anonymous are Bitcoin transactions?

I read some sources that say Bitcoin transactions are anonymous, some that say they are semi-anonymous, and some that say they are not anonymous at all. In what ways are the transactions anonymous ...
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Are NXT messages stored on the blockchain and are they encrypted or publicly viewable?

Are nxt messages stored on the blockchain? What is the character limit on these messages? And are the messages encrypted or publically viewable? If they are public, is there a site to just view all ...
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115 views

How to establish connection for mining testnet blocks?

I am new here. I really want to know how scryptcoins work so i wanted to create and altcoin to learn on something. I learned c++ years ago so i know i have some basic knowledge but sometimes i get ...
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39 views

Lost private keys. Help to recover

I have blockchain wallet but have lost the private keys of it, is tr any way to restore my private keys. Plz help
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Security and recover issues in blockchain.info wallet

I have a wallet in blockchain.info. I'm quite new to bitcoin and would be happy if someone would explain me : (1) what should I do in order to save my bitcoins if something happens to ...
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Blockchain command line tools

I was under the assumption that the bitcoind server allowed you to query the blockchain and run commands like bitcoind getbalance on any address. I'm finding out that you may query addresses in your ...
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(JAVA) Get address balance from the blockchain

I'm a merchant that is currently developing client that I will use for receiving transactions for my business. I would like my client to be able to check how much Bitcoin the address sending to me ...
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42 views

Tie Breaking in bitcoin transaction

If two nodes broadcast different versions of the next block simultaneously , some nodes may receive one or the other first. In that case, they work on the first one they received but save the other ...
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34 views

Unconfirmed Transaction >22 hrs

I realise that this might be a duplicate however I have not actually seen a sufficient answer to the question aside from 'wait'. I submitted a transaction yesterday from a blockchain wallet to a ...
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537 views

Query Transaction data based on past transaction id?

The blockchain.info API allows for quering information about a particular Transaction by its ID. But if you want to follow the coins to the next transaction, I'm not seeing what the next query should ...
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How did transaction malleability/DDOS attacks allow an exchange's internal accounting system to get “out of sync”?

This Coindesk article says that: “So as transactions are being created, malformed/parallel transactions are also being created so as to create a fog of confusion over the entire network, which ...
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Have betsofbitco.in deposits been spent?

I recently noticed http://betsofbitco.in/ went dark. Is there a straight-forward way to guess if any of the outstanding deposits have been spent in the mean time? I guess the coin could get rotated ...
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How do you create a planet-specific cryptocurrency that will ignore longer block chains from other planets?

I'm sure that cryptocurrencies will play a huge part of the economy across the solar system, when we have colonized many different planets, moons, and asteroids. But there are problems with using a ...
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How frequent are side-chain reorganizations of various lengths?

I'm wondering if anyone has collected statistics on how often reorganizations of side-chains with length 1 happen in comparison with lengths of 2, 3, or more. Related: What is the longest chain ...