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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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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1answer
38 views

Location of blockchain locally on different platforms, and structure of blockchain file?

I just downloaded Bitcoin-QT, and torrented a snapshot of the block chain that is a couple weeks old. I put the bootstrap.dat in ~/Library/Application Support/Bitcoin and started up the app. Right now ...
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3answers
106 views

What does “prev_out” and “n” mean in blockchain.info's API data?

When getting information about transactions with blockchain.info's API, every transaction contains exactly one "prev_out" object, and within that object "n" is always equal to either 0 or 1. What do ...
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2answers
29 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 ...
0
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1answer
191 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 ...
0
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1answer
461 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 ...
4
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1answer
294 views

Bitcoin-qt falls behind on blockchain, how to replace?

On Apple Mac, bitcoin-qt is 14 days behind. Never approaches current time. Have downloaded current blockchain from trusted source. Where to install? What procedure?
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1answer
28 views

I am a newbie in bitcoin and want to mine bitcoins

Hello greetings to everyone, I am Ravindra Barthwal from India and now i want to mine bitcoins but i don't know where to start even i search many times on google and everything goes away from my mind. ...
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2answers
502 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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0answers
10 views

Are there common API methods from different block explorers?

This question is to help standardization process for the benefit of API clients and those of the bitcoin-related apps and services. Please, have a look at ...
1
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1answer
34 views

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 ...
0
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1answer
257 views

Mining Bitcoin- Simple Example for transparency

I'm spending a lot of time researching bitcoin before I make any decisions about it, and most of the research is getting to know its fundamental network. Most of the easily verified information is ...
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1answer
22 views

private key access. experts?

Do you need to be online to access your address with the private key? I mean if you have the entire blockchain on your HD. I have wallets on different usb's.
4
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1answer
1k views

How to transfer only the blockchain to a friend's computer?

After installing the bitcoin client (Qt) a friend got interested as well. He doesn't have as fast an internet connection, though, so I thought of burning some DVDs with the blockchains for him to ...
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1answer
48 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 ...
2
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3answers
83 views

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 ...
1
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1answer
36 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 ...
0
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1answer
102 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 ...
5
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1answer
101 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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1answer
35 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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2answers
203 views

How to decode very huge (!) raw transactions?

I'm parsing the blockchain to extract certain information I need for a script. One thing I do is parsing transactions. What I do is: getrawtransaction <tx> decoderawtransaction <rawtx> ...
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1answer
38 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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0answers
6 views

Bitcoin accept on web site [duplicate]

We are owner of investment company. We want to accept bitcoin in our web site, please let us know about your system and I highly appreciate if you answer our questions: At first: Do you have any ...
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3answers
132 views

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 ...
0
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1answer
61 views

Given that contracts can be formed in the blockchain using scripts, couldn't a contract include a mechanism for facilitating chargebacks?

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 ...
2
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1answer
37 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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0answers
30 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 ...
0
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1answer
105 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
86 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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1answer
50 views

Chronologically sorting transactions within a block

Is there any way to chronologically sort transactions within a block?
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1answer
47 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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1answer
99 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
330 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 ...
2
votes
2answers
341 views

Can blockchain size become a blocker for bitcoin adoption?

When I run bitcoin-qt, I noticed that it is taking lot of time to download recent blocks. It gives me impression that the more transactions, the bigger the blockchain. Even today the download is ...
0
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1answer
179 views

How does blockchain.info get the addressbalance / seen date?

I am trying to figure out how blockchain.info gets the following API functions and is there any way to do these calls on a server (without using their API) perhaps through bitcoind? ...
2
votes
1answer
600 views

Saved .bitcoin directory full ~9 GB block data, won't work when copied to another system

I had to delete my .bitcoin directory in Ubuntu 12.10, after months of getting the near 9 GB of blk data files. I copied everything over to another machine (and back to the original too) and it gives ...
0
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2answers
172 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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1answer
79 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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2answers
81 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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4answers
926 views

Different balances Bitcoin-Qt vs. Blockchain.info

Why is the balance in my Bitcoin-Qt wallet different from the balance when I check the information about my address on blockchain.info? All transactions are confirmed.
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2answers
42 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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2answers
172 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 ...
0
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1answer
183 views

How to retrieve all addresses with non-zero balance and their balances?

I'm looking for a way to retrieve all address balances of addresses with a non-zero balance in the blockchain. Is there a software tool that can calculate the balances in an accessible format? Or ...
0
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2answers
264 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 ...
2
votes
1answer
252 views

“offline” blockchain querying library

Is there a library which provides all the same address/transaction querying information as blockchain.info, depending only on having a bitcoind synchronised database? There are a number of queries ...
3
votes
1answer
73 views

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 ...
2
votes
2answers
55 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 ...
0
votes
2answers
382 views

Where are my bitcoins?

I recently bought 18 euros of bitcoins (16 dec 2013). I finally got my wallet synchronized, but I still do not see my balance, nor my transactions. On the blockchain I see that I received my ...
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1answer
87 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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2answers
63 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 ...