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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If I want to run the Bitcoin client from another OS, can I direct Bitcoin to an already downloaded Blockchain on another OS' partition?

I have fast internet, and it wouldn't be too much of a struggle just torrenting the bootstrap.dat, but it would make sense to make use of an already existing blockchain and save space and time. I've ...
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Is it possible for corporate interests to incentivize securing alternate Blockchains instead of Bitcoin's Blockchain?

Is it possible for corporate interests to incentivize securing POW of alternate blockchains instead of Bitcoin's blockchain? Given the large amount of funding and/or "partnerships" announced the last ...
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How do I change the default blockchain Database download location for NXT?

I'm testing out the nxt client and was wondering how do i change the default database download location? Its currently downloading to the current folder (nxt_db).
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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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How fast is the NXT blockchain growing in 2014?

Is there a place that where I can find out how fast the NXT blockchian is growing? I'm curious because its this year (2014) where a bunch of nxt features came into the scene and was wondering how one ...
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128 views

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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3answers
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Random numbers using blockchain

How are the block hashes generated? Are they trully 100% random (generated by hardware) or is it pseudo-random (generated by software)? Can i rely on it or any other blockchain data to make a 100% ...
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Blockchain.info Wallet API: How can I send bitcoin without transaction fee

I am using Blockchain.info Wallet API for sending bitcoin. According to the API document, transaction fee must be greater than default fee. I tried to put the fee was 0 but the setting was ignored. ...
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20 views

Remove address from sequence in HD wallet

Is there a way to eject an address out of the sequence of an HD wallet? Lets say an address was used for a political donation to a regime in Namibia that may get international condemnation a few ...
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1answer
152 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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258 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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53 views

If all block chain copies get deleted, what would happen?

What would happen if all block chain copies get deleted at one time? At first, all clients would try to get the block chain from other clients, right? But this would fail. Would the "network" then ...
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How do I reduce the size of the block chain data on my machine?

The block chain file is getting rather large, ~500MB. Is there a way to trim it or clean up, or maybe configure it to be limited in the future? I am using the stock Bitcoin client on Ubuntu.
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3answers
158 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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2answers
72 views

Difference between a bitcoin wallet and the blockchain

As the title said, what is the difference between the bitcoin wallet and the bitcoin core, do i have to install both of them to work? Can I just have a bitcoin wallet?
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84 views

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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1answer
404 views

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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89 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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110 views

What is a soft fork?

When people talk about possible changes to how Bitcoin works they sometimes say a particular change can be implemented as a soft fork. What does that mean? How does this compare to a hard fork?
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How to access Bitcoin's transaction database?

I want to process the Bitcoin network's transactions. As I understand it, the Bitcoin-Qt client downloads and stores all that information locally. Since version 0.8 LevelDB has been used to access ...
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2k views

What is a hard fork?

When people talk about possible changes to how Bitcoin works they sometimes say a particular change would require a hard fork. What does that mean? Can a hard fork cause problems?
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70 views

Why doesn't the Bitcoin blockchain truncate past data? [duplicate]

AFAIK, verification of transactions on the blockchain doesn't require the full chain data and six to ten verification will be enough (which makes uses of a Merkle tree). Thus, why cannot it abridge ...
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2answers
274 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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What makes a Strange Transaction

At blockchain.info there is a tool to report strange transactions. It is reported that Transactions containing outputs from which we were unable to decode a bitcoin address According to the ...
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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 ...
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How are transactions in forks verified efficiently?

In this answer here, it's stated that Bitcoin uses a hashtable of all currently unspent outputs, in order to verify that the inputs of transactions haven't already been spent. How does this interact ...
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Blockchain transaction message length limit

When I perform a transaction on the blockchain, I can add a message to the transaction, which will then exist forever in the blockchain. Say for example I wanted to use the blockchain to store ...
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56 views

Mini-Blockchain proposal: How is the proof-chain secured against injections?

I have just finished reading the paper Purely P2P Crypto-Currency With Finite Mini-Blockchain by J.D. Bruce. While I got the impression, that the rolling blockchain as an idea might work, I was left ...
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1k views

Will the proof-of-work system end when all bitcoins have been mined?

This article from ArsTechnica is claiming that BitCoin is not such an environmental disaster, and one of the reasons they mention is that mining will come to an end. Ok, fair enough, there is an end ...
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123 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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4answers
333 views

How to find a specific bitcoin address from all the addresses?

Recently, I found a site that show all the addresses in a huge list, divided in 904625697166532776746648320380374280100293470930272690489102837043110636675 pages. The site's link is ...
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3answers
340 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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588 views

Move the blockchain to a different location

I am using the Bitcoin-Qt application on Ubuntu, but the blockchain is very large and is wasting space on my SSD drive. Is there a way that I can move it to a hard disk drive? There doesn't seem to ...
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39 views

Blockchain Parser not working on blockchain generated in regtest mode using bitcoind. Any help?

Has anyone used this blockchain parser for Bitcoin https://code.google.com/p/blockchain/ ? http://codesuppository.blogspot.in/2014/01/a-command-line-interface-for-blockchain.html I tried to parse ...
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54 views

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 much binary data (bytes) could I put in a transaction and how?

I know that some people had put text, pdf and images in the blockchain. I wonder which are the limits in order to have a minimum "bytes/btc" value in regarding the blockchain as a permanent database. ...
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Where can I find a chart of the daily supply?

there is the blockchain.info one for total supply but that very low resolution. I really was a graph of the actual new bitcoin mined on the market on a daily basis because it seems like a strangely ...
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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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Bitcoin-qt and lost local blockchain files

For some reason I've lost all data in my .bitcoin directory except the wallet.dat file. Now bitcoin-qt shows 0 balance, and it's 5 years behind sync. Is this possible to restore coins in this case?
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23 views

Why do Bitcoin API services offer Block details?

I understand having APIs around addresses and transactions, but I'm less clear why I need to know what's happening with a Block(s). This is to confirm one's transactions? Might someone provide some ...
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24 views

Local Testnet3, where do the new coins get sent to?

I'm trying to setup a local testnet with multiple nodes. Currently I have three nodes, and their mining powers are almost the same. When I use listaccounts RPC call, all the wallets have 0 coins. ...
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Bitcoin testnet: “Bitcoin is downloading blocks…” and other problem

I'm trying to setup a local testnet with multiple nodes. Currently I have three nodes, and their mining powers are almost the same. Things have been quite ok so far, except some problems that I need ...
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1answer
130 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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59 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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884 views

Can I change the bitcoin block-data directory from /home/user/.bitcoin/blocks to something else? [duplicate]

I have two users on my Linux system, daemonuser, which runs bitcoind and abeuser, which runs Abe. Whenever I start Abe, I am told: Skipping datadir /home/daemonuser/.bitcoin/blocks: [Errno 13] ...
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1answer
90 views

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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65 views

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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971 views

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? ...