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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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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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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548 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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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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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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125 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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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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483 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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286 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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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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245 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 ...
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Why aren't bitcoin transactions processed and verified by normal bitcoin clients?

My understanding is that the blockchain is exclusively built by miners. My question is, why isn't that verification done by every bitcoin client - kinda like p2p file sharing programs allowed people ...
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How does one programmatically “walk-back” on the block chain?

I'm thinking (probably erroneously) along the lines of a linked list and C pointers, but how would one follow the block chain from some block all the way back to the genesis block? The previous ...
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123 views

Help understanding the blockchain [duplicate]

I am trying to better understand the fundamentals of the BLOCKCHAIN. I am not technical and am hoping someone can offer up an explanation in LAY TERMS. Thanks in advance.
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Transactions show up on blockchain but not in multibit? [duplicate]

1JPEobzLgKo5EKEfDVN8aJ61Pdryse6ccf This address shows transactions I was not aware of for unknown reasons, and does not show up in multibit(version 0.5.16). Which one is accurate, and how can I sync ...
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132 views

Running two bitcoin instances on a linux server, can't get peers on second instance

I am running two bitcoin instances using the method described in this previous thread: http://bitcoin.stackexchange.com/a/13584/6024 I have set the new datadir and each instance has a different ...
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317 views

LiteCoin Wallet balance does not match block-explorer.com

My Litecoin wallet version v0.8.6.2-beta is showing a balance of 26.579 ltc When I query http://block-explorer.com/address/LejrG23b2HcjqPRbZU8UWFxZhdJTUc75pS it is showing 0 balance. I just sent 2 ...
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764 views

How do I find the transaction ID of what I just transacted?

If I send or receive something (with Bitcoin-QT), how can I get the transaction ID of that transaction? context: I'm playing satoshi bones and they have verification code I can run to make sure ...
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69 views

Checks to Verify money sent to any address in a transaction

I'm using wallet-less bitcoin daemon (it just syncs blockchain) – the purpose is to read blocks and transactions in them, and do some useful things. This particular question is focused on determining ...
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Bitcoind doesn't find transactions / synchronize / update until last block from Testnet

I set up bitcoind as server. It downloads the testnet blockchain but it is inconsistent with public data: http://blockexplorer.com/testnet/q/getblockcount 182951 (As of 18/02/14) And bitcoind ...
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Do I need to wait for blockchain to complete to use private key elsewhere?

As the title says: My blockchain sync still needs to sync 56 weeks, but I want to export my private keys from the bitcoin qt wallet to blockchain.info. Is it possible to do that without waiting for ...
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What is the NTX ID that Mt. Gox refer to in their Feb 17th Statement?

Mt. Gox have released a statement concerning their recent withdrawal problems. In order to launch the new system, we are going through the following steps: Re-indexing the entire ...
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How will Bitcoin deal with the year 2106 problem? [duplicate]

The Bitcoin protocol currently uses uint32_t to record timestamps. While the year 2106 is still a long way off, I'm wondering why not just go with int64_t and be done with it?
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Will the performance of calculating the balance for an address degrade over time?

If balances are calculated on the fly by offsetting all the transactions flowing in and out of a public address, will this degrade the performance of calculating such balances in years to come, i.e. ...
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126 views

What trust am I placing where when I use Electrum?

I have read that Electrum never is given your private keys (which makes sense), but I'm still unsure what sacrifices it makes in order to not require you to not store the entire ~14GB blockchain. So ...
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Transaction fees when a block chain is discarded

I'm a bit new to the bitcoin system, so I apologize if this is a "noob" question. A user attempts to take all the unverified transactions it knows about and aggregate them in a chain block. The same ...
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Should there be a minimum transaction limit to prevent dust spam?

With all these reports of people receiving spam through dust transactions (e.g. Enjoy Sotchi, Bitwars etc) what would be the implications of setting a minimum transaction amount on the network? Why ...
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Transaction Malleability in the blockchain

How does a transaction malleability look like in the blockchain? Are there any examples?
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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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Clean blockchain? [duplicate]

Wouldn't it be theoretically possible, to just cut everything older than say 4 weeks from the blockchain? What use does transaction data from 3 years ago have anyway? Isn't it also safer in terms of ...
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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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295 views

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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140 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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138 views

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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208 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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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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46 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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222 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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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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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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Will old accepted blocks ever be removed?

Or are they kept forever such that the chain from the Generation Block will always remain verifiable?