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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Just installed bitcoin, but it won't connect

Total newbie at bitcoin; long time Linux user. kubuntu precise 64: My first attempt was just to download it (a slightly older version than the one from the ppa below), untar it and run the ...
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62 views

Can I run bitcoind without downloading new blocks? [duplicate]

I want to run bitcoind to interact with the daemon, but having bitcoin download new blocks and verify them is taking a toll on my CPU. I do not want the latest data - I just want the daemon to be ...
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61 views

Tracing Bitcoins to their original blocks

Can I find (always, without fault) the specific set of blocks from which the Bitcoins that I hold originated? If yes, would such a trace-back be computationally costly?
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370 views

How is a side-chain merging back to Bitcoin chain protected against double-spend? Where are the side-chain mining fees?

I am struggling to understand the concept of "side-chains" that's discussed a lot lately, but never trully explained. How I understand "side-chain": it's an altcoin, with a separate blockchain, with ...
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82 views

Using blockchain to publish downloadable software verification codes

What is the point of comparing sha256 of downloaded file with published on the same website code? Why can't developers of currencies publish file version and sha256 hash on blockchain as alias or ...
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84 views

How can I download the blockchain from own, trusted source?

I have two computers with two different bitcoin-qt wallets: Very heavy-weight desktop with a great internet connection. Less powerful laptop with relatively slow internet. I would like to download ...
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81 views

Can I download blockchain updates from somewhere?

I use Bitcoin only on rare occasions - say once every month. I want to avoid long waiting times for downloading and verifying blocks that consequently await me when I reopen bitcoin-qt. There are many ...
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184 views

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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109 views

Listening for changes to my own wallet in the blockchain

I would like to be notified of changes to any of my many wallet address as soon as they happen and then programmatically take action. I have been using wallet notify but this has been giving me really ...
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96 views

Is block height always sequential?

Is block height always sequential? Can it serve as a 100% reliable block counter in case if I want to check whether I missed a block or I need to account for any corner cases?
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204 views

RPC calls fail in testnet mode, but not normal mode?

I'm running bitcoind on a debian web server. If I run in normal mode, i.e. "bitcoind -daemon," then it seems to work completely fine. [birdseye]$ ./bitcoind -daemon Bitcoin server starting ...
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81 views

multibit balances wrong, not correct for any individual address

In my multibit wallet, it reports X bitcoins. But no address in that wallet contains exactly X bitcoin, and the total reported amount should be greater than X. The reason this is stranger than ...
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164 views

How to create a SPV client?

What are the steps a SPV client takes in order to sync? Connect to a peer Set bloom filter for wallet addresses Download all block-headers since latest checkpoint Request every block again with ...
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93 views

Bitcoin URGENTLY Need Blocks Files - Download them from some Website [duplicate]

I have been doing this synchronization procedure (first time) in bitcoin-qt for over 85 hours and it only came to 31 Weeks Behind. Withdrawed from localbitcoins like 95 hours ago and obviously this ...
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115 views

Why there are blocks with single transaction in blockchain?

Just opened blockchain.info and found two blocks with single transaction on the main page: 292942 292947 Isn't it strange? More than this, block 292941 was issued just minute before 292942 and has ...
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85 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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165 views

get public key from wallet.dat

Is there a way to get the public key of a given wallet.dat to check the balance in the blockchain to avoid having to install the wallet and read all blocks?
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195 views

Is there any altcoin with improvements in blockchain download time?

Let me introduce my idea. Given: sizeof( Blockchain ) = 16Gb Downloading of one avi film 16GB from the pirate bay ( 5mb/s ) = 2-3 hours Downloading of bitcoin's blockchain ( 5mb/s ) = 2-3 days One ...
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How is over-spending one block apart prevented?

So, let's say you have a wallet with 20BTC, and you have a flow like so: You send 15BTC to A in block 1 You send 15BTC to B in block 2 What happens if at block 1 there are two chains across ...
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76 views

Where is the code that sends generated Bitcoins from mining to the wallet?

I was just looking through the Bitcoin code but since I am relatively new to C++ I was wondering, if anybody could tell me where the code responsible for sending coins generated through mining to the ...
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54 views

Bitcoind need blockchain to sign transaction

I'm trying to sign a transaction using bitcoind via rpc. Here is the request I send. signrawtransaction ...
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62 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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66 views

How is the reward that you got after calculating the right hash added in the blockchain?

I have a question. If for each transaction, the hash is calculated and so the pool who calculates it gets the bitcoins as reward, now getting reward means bitcoins gets added to your wallet, but this ...
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Is there any relation between the block version field and the one of the transaction?

I am struggling to validate my custom miner against the testnet network and I can't seem to add a block of mine to the chain. I've noticed that all the other miners are appending version 2 blocks, so ...
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First block of blk00000.dat from bootstrap.dat doesn't contain genesis block

I downloaded the bootstrap.dat file from the torrent at http://sourceforge.net/projects/bitcoin/files/Bitcoin/blockchain/ and placed it in the .bitcoin directory of a new Ubuntu installation of ...
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79 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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104 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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78 views

What is the fastest way to determine whether an address exists on the blockchain?

All I want is to determine whether a given address has ANY activity on the blockchain. I've seen projects like bitcoin-abe, which might work, but I wondered if there were a simpler way than using ...
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438 views

Sending bitcoins from wallet without downloading the blockchain or giving up control

I can generate a bitcoin wallet at bitaddress.org, and I can verify that I have received payments at blockchain.info. But if I want to send bitcoins from my wallet, I know only of 2 ways: Use ...
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75 views

Verification of transaction once trasaction is broadcasted

I have few doubts regarding verification of transaction and am trying to find answers from last few days. I agree similar post exist in this portal but I am not getting satisfactory answer for my ...
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37 views

Restore New Funds after Blockchain Backup

If I transfer money into my Blockchain account after receiving my Json wallet backup by email, would it restore recently added funds?
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36 views

Using a blockchain type system for different purposes [duplicate]

I was wondering, not that I really took the time to investigate much yet but.... Wouldn't it be possible, to do many different things, with the blockchain concept? Maybe i could build a "browser" ...
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126 views

Bitcoin blockchain search algorithm and consistency policy

The blockchain looks like a double linked list, and all the transactions are stored into each block. What kind of algorithm does bitcoin use to find a specific transaction efficiently, since the ...
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172 views

mtgox failure… any implications for bitcoin/ecurrency protocol design?

last heard, estimates are Mtgox lost about ~$½B ... apparently the current bitcoin market cap is around ~$8B ie Mtgox failure roughly somewhere around 1/16th the entire market cap of bitcoin, a ...
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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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What happens if I fork an older block chain and rejoin the network later?

Let's call it a "time machine attack". Suppose I have an isolated network of n clients with a significant hash rate, install my client software on that and start mining on an older blockchain. Since ...
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Given that contracts can be formed in the blockchain using scripts, couldn't a contract include a mechanism for facilitating chargebacks? [duplicate]

While I understand that chargebacks, or the lack thereof are an important feature for encouraging merchants to adopt bitcoin, the reverse may be true for consumers. There is probably a balance to be ...
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747 views

How to create a bootstrap.dat file?

I want to create a new bootstrap.dat file for a Dogecoin. How do this kind of files are created and how can I create one? What tools should I use? any answers/links/references are appreciated. I have ...
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digitalcoin wallet won't sync

I've had my digitalcoin wallet open for a few days now, hoping it would eventually sync back up but it's seemingly stuck, not necessarily at a specific block, but around 3 days back, whichever block ...
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140 views

How much money is a double spend worth?

I keep hearing people say that 0 confirmations are safe at small dollar amounts because it would take more money to do a double spend hack. At what value does it start to become unsafe to trust a 0 ...
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51 views

Order of transactions within a block

Does the Bitcoin protocol guarantee that within a valid block, if transaction B spends the outputs of transaction A, A will always precede B? Or is it possible to have B before A?
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131 views

Hypothetical situation: the Internet gets split in two, what happens with Bitcoin?

Let's suppose, that at some time the Internet gets split in two, possibly because of wartime, or another possibilities (there was once a situation, when Egypt managed to split the internet in their ...
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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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297 views

Is it possible to run bitcoind without downloading the blockchain?

I'm using bitcoind on a project, and I only need to send bitcoins to myself (from one wallet to another), so trust is not a factor. That being said, is there a way to run bitcoind without needing to ...
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563 views

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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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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328 views

Is it possible to add a miners fee after you send your bitcoins?

I accidently sent btc without a miners fee and i need it to clear asap. But as far as I can tell it's going to take days if it goes at all. Is there anyway I can pay a fee on top of what I've already ...
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116 views

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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How to check on speed of the syncronizing progress? [duplicate]

I've got the feeling my network syncronization sometimes stops. I'd like to keep an eye on incoming information. Preferably something that shows XXX Kb/s or that simply shows me the data that is ...
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258 views

Does a new block necessarily include all transactions that occurred before its generation? What about network latency?

I read What exactly is Mining? and What are bitcoin miners really solving?, but was left wondering: What happens if a new transaction comes in, whilst mining? To answer that, I found Do transactions ...