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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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 ...
4
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1answer
196 views

Is a full blockchain fork possible?

Let's say someone creates a blockchain fork starting from the genesis block, when the difficulty was absurdly low compared to today; then he starts mining new blocks from there up to the current block ...
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1answer
60 views

Do receiving addresses expire on Multibit?

Okay so I have tried Resetting Blockchain and Transactions plenty of times. The only thing is I used an old receiving address that I used about 2 months ago. Do these addresses expire? Can they only ...
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83 views

What Prevents the number of Bitcoins from being increased? After 21 Million? [duplicate]

Can the bitcoin MAX_MONEY attribute simply be changed from 21 Million to a higher number? If not what prevents this from being done? What would happen to existing addresses and accounts if MAX_MONEY ...
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0answers
35 views

Reclaiming Disk Space [duplicate]

According to section 7 of the original bitcoin spec. by Satoshi: Once the latest transaction in a coin is buried under enough blocks, the spent transactions before it can be discarded to save ...
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0answers
28 views

How many addresses are in blockchain? [duplicate]

I understand that client like bitcoin-qt can generate addresses indefinitely, but only true or active addresses are in blockchain. How many addresses are in blockchain? Is somewhere statistics data ...
2
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1answer
166 views

Running Bitcoin Core for first time

I was using the official Bitcoin client some time ago. It was version 0.5 I think. Then my computer crashed and didn't use Bitcoin for a long time. I was lucky because I had a backup of the wallet. ...
9
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2answers
544 views

How to minimize risk when accepting zero confirmation payments?

I'm trying to setup a way of accepting Bitcoin payments in real life situations, where waiting for confirmations is typically not an option. I understand this is never 100% risk free (especially with ...
6
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1answer
493 views

How does BitCoin prevent fraud during confirmation period?

I'm trying my best to understand how bitcoin works and while I've grasped the basics, there's a lingering question: What's to stop me from spending my bitcoin multiple times during a confirmation ...
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1answer
163 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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1answer
61 views

I am a newbie in bitcoin and want to mine bitcoins [duplicate]

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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0answers
156 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 ...
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1answer
87 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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1answer
65 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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2answers
1k 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
129 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 ...
2
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2answers
91 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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1answer
129 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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3answers
232 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 ...
3
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3answers
151 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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2answers
125 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
274 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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1answer
95 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 ...
4
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2answers
207 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
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2answers
113 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 ...
2
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1answer
156 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 ...
2
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1answer
132 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
233 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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2answers
216 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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3answers
156 views

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 ...
5
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1answer
80 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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1answer
60 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 ...
0
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1answer
94 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 ...
3
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1answer
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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1answer
33 views

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 ...
2
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2answers
269 views

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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1answer
95 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, ...
0
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1answer
117 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
91 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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2answers
913 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 ...
2
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1answer
90 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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44 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" ...
2
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1answer
172 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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2answers
175 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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257 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
169 views

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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1answer
132 views

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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1answer
1k 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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281 views

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 ...