The blockchain is a list of all transactions that have occurred using the Bitcoin currency. DON'T USE THIS FOR THE SERVICE NAMED 'blockchain.info'!

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1answer
385 views

Why can't bitcoin miners modify transaction outputs?

I am learning the Bitcoin protocol by reading the bitcoin developer reference documentation. As far as I know, a raw transaction consists of: Version (which is always 1) Inputs. Each input contains:...
4
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3answers
349 views

Can a Bitcoin block be less than 1mb?

Can a Bitcoin block be less than 1mb? To my understanding, a miner receives broadcasts. However, if not enough transactions come in, then would it just prematurely hash the block?
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2answers
843 views

How many blocks are there in blockchain as of today?

I have currently downloaded 300,000 blocks and the last one is generated 1 year and 19 weeks ago. I wonder how many blocks are more to go, before I am up to date.
3
votes
1answer
125 views

List of blockchain explorer APIs?

I'm gathering a list of Bitcoin / Blockchain APIs. I mean web (REST) APIs that allow you to do basic blockchain queries through http(s) API calls, such as: getting the balance on an address, getting a ...
3
votes
1answer
62 views

What's the maximum possible utxo growth rate now? Can that be turned into an attack?

Now bitcoin unspent transaction output growth rate (not total size) can be, 260k utxo/day (3×60×60×24). With 8MB blocks, that's 2.8 million. Single 1 bitcoin output can be split into 1000 x 1 mBTC ...
9
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1answer
816 views

Why do you need the *complete* blockchain to mine bitcoins, why not just the last n blocks?

I understand that to mine bitcoins you need the hash of the previous block, and in order to resolve possible forks. But why not just have the last 100 blocks (or more whatever is appropriate) and keep ...
2
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2answers
285 views

Why has this blockchain transaction not confirmed?

ea5ee0a3734356a71b2b39deafb656715bad42fb297497f7f694d4a7a0f6335c Is due to the fee being low 0.0001? or something else?
2
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0answers
34 views

Differences between MemoryBlockStore and SPVBlockStore

What are differences between MemoryBlockStore and SPVBlockStore in bitcoinj? Which should be used for downloading the blockchain and why? Can I use same SPVChain format file for all wallets?
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0answers
34 views

Reset bitcoin blockchain checkpoint to mine 0th block [duplicate]

I want to start a new block chain and mine the 0th block, but I guess the hardcoded checkpoint in chainparams.cpp won't allow that. I guess I need to reset the checkpoint hardcoded as follows before ...
4
votes
3answers
240 views

Why is sharding not possible with a distributed blockchain?

Hi guys I've been reading a lot about the problem of scalability in crytocurrencies and how to run a full bitcoin node is not a possibility on a mobile device for example, as a result we become ...
2
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1answer
313 views

Picture of blockchain

Can anyone point me to the picture I saw somewhere but can not find it anymore where blockchain is represented as a line of blocks chained together. There was a locker on each little block, and each ...
7
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3answers
575 views

Selling copies of blockchain database on disc

Is it ethical / legal / at all possible to burn a copy of the Bitcoin (or any cryptocurrency) blockchain to a disc, and then sell the disc? Would there be any additional issues if we included a copy ...
1
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1answer
153 views

How smart property works on basic bitcoin blockchain?

How smart property works on basic bitcoin blockchain? I am not sure that how to make token, that is tied with a particular object, on the bitcoin blockchain. I've already know I can use such kind of ...
3
votes
1answer
210 views

How do I retrieve the funds on my Core wallet when I can't synchronize the blockchain?

I have about $200 in bitcoin but my wallet (Core) won't synchronize the blockchain (it's been doing this for days) since for some reason it got corrupted (As it tends to do say every other month) and ...
1
vote
1answer
216 views

A conflicting transaction has been detected in our memory pool. The transaction hash displayed below may change

SO i received this transaction from my other wallet 1) https://blockchain.info/tx/06810d392213a7453bbe6ad4ab95c0892875b0db2b56b3db5ef942b0a42eced4 for 1.02BTC and sent these for 1btc and 0.2btc ...
1
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0answers
57 views

Given the latency and hash rate for a mining pool, is it possible to determine the expected number of accepted blocks? [closed]

Assuming there is only one node to communicate to, can we determine how many blocks mined by a pool will be actually accepted into the block chain?
0
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0answers
107 views

bitcoin api blockchain - where is the money?

I have made several transactions via blockchain API, and I'm getting the callback everything works normally. But today when I see my balance is zero and it has no transaction history. Transactions ...
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0answers
34 views

Is it possible to search for an transaction to or from an address with a time period filter?

How can I search for a transaction to or from a certain address in the block chain within a particular time period? I am trying to answer if this transaction occurred on 17 Oct 2014. Hence, instead ...
2
votes
2answers
132 views

Could Blockchain be used for a different currency, leaving bitcoin behind?

I’ve seen articles lately that many large banks including, HSBC, Deutsche Bank, Citigroup, and Bank of America are exploring the use of Blockchain. Knowing these banks, they would surely love to use ...
1
vote
0answers
125 views

blockchain - Anti-virus service

I hope this is the right place to ask a question on how does block-chain help this theoretical requirement. I have also asked this question on SO; so far, no response. And, Ethereum SE is still in ...
3
votes
2answers
555 views

What is the genesis block?

What is the genesis block? In which ways is it important or different from other blocks?
2
votes
1answer
71 views

Where can I find the structure and layout of what exactly gets hashed by miners?

I understand that a miner has a list of bitcoin transactions since the last time a a block was discovered. The first entry is the reward for who discovered the previous block. As more transactions ...
2
votes
1answer
284 views

Export Private Keys from Bitcoin-QT

I am still attempting to complete the receipt of a payment in BitCoin-QT. The initial synchronization is beginning to be a hassle so I thought I might get my key and transfer my wallet to Blockchain....
2
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2answers
145 views

Wouldn't bitcoin benefit from distributing partial blockchains over each node?

Why doesn't each node store only a portion of the blockchain? For example, if you had 100 nodes, each node would store 10% of the blockchain. This would amount to significant overlap of each aspect ...
2
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0answers
68 views

Bitcoin .11 Initial Blockchain Download Problem with OS X 10.10

I am loading the blockchain for a new wallet. Initially I had problems due to ISP issues. This issue is fixed and I now have 8 outbound connections working well with ping times ranging from 50-800 ms. ...
1
vote
1answer
289 views

What does it mean ERROR code=-28, message=Activating best chain?

I am using insight-api for get block chain information. When i am trying to start insight i am getting error "ERROR code=-28, message=Activating best chain..." . I saw this error first time,please ...
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0answers
15 views

Node Operators Reward [duplicate]

Why don't we implement a Node Operator reward program (in the core) or if such implementation ever existed what would be the overall (Downside,Cause for concern, etc) Why don't we use the Miner Fee ...
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0answers
165 views

Basic transaction validation rules, Node accept to pool policy

I am trying to collect all infromation about adding and verification transaction to Blockchain. Exist 2 types : add transaction to RawMemPool and add Transations included in block. Could any ...
10
votes
1answer
479 views

Is there some client like Bitcoin core, but which highly compresses the blockchain?

I have been using Bitcoin Core for some months. I need a fully fledged client as I want to help the Bitcoin network. But the blockchain is so huge. I'd love to see some other client, which highly ...
2
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0answers
45 views

What happens when Bitcoin's blockchain grows to 1 Terabyte in size? [duplicate]

If bitcoin is to succeed surely the blockchain design has to be redone. Are there any other cyrptocurrencies with a different blockchain design than bitcoin?
4
votes
1answer
136 views

Blockchain Application

I am currently doing a project that requires blockchain to be applied to other systems. I was wondering where I can easily download the blockchain database and which is the best way of understanding ...
2
votes
1answer
137 views

How to synchronize with the bitcoin blockchain via bitcoinJ

I'am writing my very first application using bitcoinJ api and I got a bit stuck. Maybe somebody can tell me what I am missing. My practice app wants to write a sample contract in the bitcoin ...
1
vote
1answer
132 views

Merging blockchains after algo change

I have a question for the community and im hoping a few informed individuals could get me some insight. When a cryptocoin changes algorithm (eg. scrypt to X11), how does one achieve the merging of ...
2
votes
1answer
64 views

Get blockchain info for exchange transaction

I'm sorry in advanced if this questions are dumb but here goes ... Does all buy/sell bitcoin related transactions made in exchanges get logged in the blockchain? if so can they be found and/or ...
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2answers
207 views

Can a smart mind explain block difficulty calculation in lay terms?

I tried to read it here: https://en.bitcoin.it/wiki/Difficulty But it is closer to a rigorous math proof than to an explanation. I am interested to understand that so I can understand what makes a ...
2
votes
2answers
193 views

How can a block be considered more difficult to solve/hash than another one?

In this answer: http://bitcoin.stackexchange.com/a/760/28219 It is said: Because of all this work, when a Bitcoin client signs on to the network it can trust the block chain that was most ...
3
votes
2answers
188 views

When does a miner decide to stop collecting transactions and start calculating hashes to try to win?

I am confused about whether a miner chooses to wait for more transactions (more fees) or starts as soon as it receives the first transaction from the network. Once a miner has started calculating the ...
3
votes
1answer
141 views

What is the protection against a malicious node with a bad block chain?

How does a bitcoin node protects against connecting to a node with a forged block chain? How does it say: "Ok, I just got this block chain and it is a valid/legit one" ?
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0answers
30 views

Validate chain from `valid-headers` to `valid-fork`

The getchaintips JSON-RPC returns multiple branches of the blockchain. Chain tips can be in various statuses. The active and valid-fork are already validated chains. There is a valid-header valid-...
3
votes
5answers
2k views

How to store data on the blockchain?

I am wondering if it is possible to give someone a bitcoin transaction ID and with that he can read some hidden data, like the blockchain.info notes on transactions, but for real, stored in the ...
2
votes
0answers
59 views

Get as many blocks as possible (stale, invalid, orphans)

I would like to download (and access) as much blocks as possible - including stale (extinct) blocks, orphans blocks and invalid blocks. I have 0.11 official client. My node is already synchronized but ...
1
vote
2answers
252 views

Fastest filesystem for blockchain?

I am running Linux with a harddisk. Currently the blockchain is on an NTFS partition, which probably isn't the fastest. Which filesystem should I choose? As I understand it, a Bitcoin node will only ...
2
votes
1answer
160 views

Is it possible for computing power to increase quick enough to break mining retargeting?

So from what I understand, mining bitcoins basically becomes more difficult as more bitcoins are mined. This is done so computing power doesn't get so strong that bitcoin mining becomes trivial to ...
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vote
3answers
100 views

Wanted to back up blockchain to save space, now I cannot open bitcoin QT?

I wanted to back up the blockchain on my hard drive as it took around 50 GB on my laptop. I did so and deleted all the blk000.dat and the rev000.dat from (~/Library/Application Support/Bitcoin/) which ...
3
votes
1answer
92 views

Best method for getting bulk address information (total sent, received, and final balance)

I need to go through a large list (about 100 000) of bitcoin addresses, and, if they have a final balance, find that as well as the total sent and recieved. I am working in python, and I have looked ...
0
votes
1answer
348 views

Why hasn't my bitcoin transaction gone through?

So about 3hrs from now I made a transaction to a different wallet of mine and the money didnt come through in 20mins I checked the blockchain and the number of confirmations kept rising and its up to ...
3
votes
1answer
351 views

How to handle POST data sent from Blockcypher WebHook API

I've been trying to get this to work for the past 3 days and I've all but given up on it. Basically, I've used requestb.in to monitor if any POST requests are going through; requestb.in always ...
0
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1answer
273 views

Please help! How do I transfer my wallet from bitcoin core to MultibitHD?

I (should by now) have bitcoins in my wallet,I sent them to my wallet whilst i was using bitcoin core but after taking days to sync (and it still hasn't synced) i have given up and installed ...
2
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0answers
63 views

Is there a service that can track how a coin flows from one wallet to another visually?

I sent some coins to an address and would like to track how these coins are flowing into other wallets. Is there a service that shows this visually? My main point is that I want to know if these coins ...
0
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1answer
35 views

Can a client leave its mark on the blockchain?

Would it be possible for a client (eg the core client) to leave its mark in the form of META data on the blockchain or even in the mempool so that we know that this client was used to create or send ...