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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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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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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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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38 views

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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1answer
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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1answer
238 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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22 views

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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22 views

multiple parties to sign a transaction before being broadcast (or after, but either way be associated with)

Lets say someone was writing a transaction solely to denote the existence of something, or a timestamp, or writing something in OP_RETURN Could that transaction be signed by other addresses, kind of ...
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1answer
72 views

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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75 views

Chronologically sorting transactions within a block

Is there any way to chronologically sort transactions within a block?
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1answer
25 views

On quering the blockchain, can someone read what transaction took place? [closed]

Like considering the Alice Bob ex where Alice is the customer and Bob is the merchant. If Alice and Bob signed a contract where alice will pay bob on the delivery of a service. The transaction took ...
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137 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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1answer
69 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
371 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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1answer
32 views

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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2answers
241 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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129 views

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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Block nonce predictable

Is the block nonce predictable in any way? It seems to be a proof of work on his own just like the block hash, but may a miner force a mined block to have a specific nonce? (if his hashrate allows him ...
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1answer
34 views

Include checksum in a transaction

Is it possible to include a file's checksum in a transaction? Not necessarily in Bitcoin's current blockchain due to the now limited OP_RETURN feature, but just in the blockchain/transaction concept ...
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3answers
312 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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1answer
43 views

How does NXT prevent blockchain bloat since it does so many different things with its blockchain?

How does NXT prevent blockchain bloat since it has a built in message system and other features? Wouldn't the NXT blockchain grow to be really big in the future and pose a problem for people storing ...
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Why does Bitcoin store all transaction inputs and outputs, instead of just an “account/balance” ledger?

From what I can tell, the Ethereum blockchain just stores accounts and balances - why did the original Bitcoin developers choose the method of storing all transactions for validation instead of just ...
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1answer
94 views

How do I iterate through the entire Blockchain using RPC?

I'd like to iterate through the entire block chain using RPC. The process I intend to do is: getblockhash 1 getblock (input of #1 here) iterate through each transaction with GetRawtransaction ...
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1answer
31 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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Blockchain Pairing API

Have anyone of you figured out how can we use devices pairing in 3rd party applications? I've found that pairing QRCode looks like this: "1|<blockchain_login>|<some_hash>", where ...
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1answer
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Strongest vs Longest chain and orphaned blocks

Satoshi writes at the bottom of page 3 of his white paper that "If two nodes broadcast different versions of the next block simultaneously, some nodes may receive one or the other first. In that case, ...
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1answer
105 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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4answers
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Are there any works of science fiction out there that relate to blockchain technology?

It feels like science fiction is lagging behind Bitcoin and the blockchain technology that is powering it. Are there any writers who have discussed similar technology in their stories? Even in the ...
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1answer
145 views

(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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2answers
121 views

Is there database of orphaned blocks?

Is there database of orphaned blocks? https://blockchain.info/orphaned-blocks does not work right now Does anybody keep them? Also I am looking for those transactions which were not included in ...
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1answer
58 views

Confirmation limit

When seeing transactions I see that the number of confirmations keeps increasing without any limit. I wanted to know if there is any time limit on including a already confirmed transaction in a block ...
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3answers
79 views

How To Lower The Disk Space Needed For Full Blockchain?

I'm looking to run bitcoind on a virtual machine. However the main nets Blockchain size is over 21GB, and growing. Is there a way to compress this down or lower the amount of disk-space needed for ...
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1answer
55 views

Is it possible that someone forks the chain?

I'm not sure I understood everything but all the clients always keep the longest chain, ok. So, what happen if an evil person inject bad transactions in a block and successfully mine it (given the ...
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1answer
561 views

Uses of computing power by bitcoin miners

How much of what this article says is true? I thought I had read that bitcoin miners are the ones who maintain the blockchain. Do they also do something other than maintaining the blockchain? In ...
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2answers
224 views

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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1answer
81 views

What percentage of Bitcoins stored in a multi sign address?

I am looking for a statistic of the usage of multi-sig addresses over time. More concrete: what is the percentage of Bitcoins stored in a multi-sig address over time.
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New To Bitcoin…Please Help! Bitcoin not received from sender to Armory Wallet!

I am in desperate need of assistance! I am new to Bitcoin so please apologies for the lack of knowledge in these matters guys....We all have to start somewhere ;) I sent my Bitcoins from the ...
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3answers
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Can the Bitcoin blockchain eliminate the need for Trusted Computing in Smart Contracts?

Let me preface this by saying that I'm a novice, but this is my rough understanding of how Bitcoin's blockchain works. (This is largely based on blog posts like this one.) If person A wants to ...
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1answer
58 views

Cannot allocate memory

EXCEPTION: 11DbException Db::get: Cannot allocate memory bitcoin in ProcessMessage() Downloaded 250k blocks, now it won't run anymore i'm running ubuntu 12.04, I have 20GB HD and 1gb ram. any way to ...
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37 views

Blockchain and Bitcoin client difference of amount

I just made a transfer of 0.06 BTC, you can look it up on Blockchain.info The problem now is that my receiving client (Multibit) doesn't show those 0.06 BTC, it only shows 0.0001 BTC have been spend ...
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1answer
52 views

What is current size of various databases in Bitcoin Core as of July 2014?

This question is related to question: What is the database for? What is size in MB of: blockchain itsef - blocks/blk*.dat blocks/index/* chainstate/* blocks/rev*.dat Is the size of chainstate and ...
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1answer
54 views

Can you assume that all inputs to a Bitcoin transaction are controlled by the same person?

When you are looking at a Bicoin transaction in the block chain and it has inputs from multiple addresses is it safe to assume that those addresses are all controlled by the same ...
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What are the keys used in the blockchain levelDB (ie what are the key:value pairs)?

I am wondering if I can use node.js and levelup to access a copy of the blockchain database directly. But from what I can see, I need to know the name of the key(s) before I can get any data, as this ...
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How much space does the blockchain take up per day and per hour when running bitcoinQT on my computer?

the blockchain is about 20GB today, but i was wondering how much space does it take up each day if i were to leave bitcoinqt on regularly? also by hour? reason why im asking is im thinking about just ...
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1answer
29 views

How to find a block containing a transaction using transaction hash only?

Well, the title says it all. I have a transaction hash and I want to find this transaction in the blockchain. I am working with bitcoinj. I am probably missing something very obvious here, but I ...
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2answers
162 views

Is there a database of all transactions?

The blockchain is a database of all valid transactions, but is there a company/project that also logs all transactions which were broadcasted, but didn't made it to the chain? Blockchain.info for ...
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1answer
40 views

Purpose of a BlockChain in local wallet application

I have installed the BitCoin wallet application on my PC, so that I can cold store my BitCoin. It's "Synchronizing with the network" and has 272 weeks of BC left to download (painfully slow!!) What I ...
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1answer
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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 ...