Questions tagged [blockchain]

This tag should be used for questions pertaining to the blockchain. The blockchain is a list of all transactions that have occurred using the Bitcoin currency. It consists of blocks which are linked to each other, and each block consists of transactions. DON'T USE THIS FOR THE SERVICE NAMED 'blockchain.info'!

282 questions with no upvoted or accepted answers
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votes
1answer
458 views

Can*t call chainActive.Tip()->nHeight in core.cpp

I want to call chainActive.Tip()->nHeight in core.cpp. It is not possible, I am interested in every idea. https://github.com/LIMXTEC/BitSend/blob/DEV-joshafest/src/core.cpp Here is an example : ...
4
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1answer
135 views

What exactly is a "blockchain developer"?

Hello everyone. This isn't specifically a bitcoin thread but due to recent events I think it is important that people get an understanding of the real Elon Musk as I have no doubt he will try and ...
3
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2answers
61 views

Delay of a revocable transaction in the Lightning Network

The Lightning Network Whitepaper describes the concept of Revocable Sequence Maturity Contracts (RSMC), which allows a commitment transaction to be revoked during a predefined delay after the channel ...
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4answers
3k views

Are there any opensource PHP cryptocurrency exchange/marketplace

As the title suggest, are there any opensource PHP cryptocurrency exchange/marketplace. Most of the ones I found does not seem to work or are abandoned.
3
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0answers
610 views

Verification progress decreasing when validating genesis block

I've been experimenting with the litecoin source and have decided to make my own token network for personal use. I've mined my own genesis block, and assigned unique identifiers for base58Prefix and ...
3
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0answers
492 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
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0answers
824 views

Querying insight-api to dump all addresses with a positive balance

It's been some time I've been using 'insight-api' (https://github.com/bitpay/insight-api) and I couldn't find any documentation / anything helpful to query leveldb in a way that all addresses with a ...
3
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1answer
169 views

What is the best way to implement withdrawal in online service?

Suppose we have a service, which holds user balance in Bitcoin. How to implement withdrawal from bitcoin perspective? Which RPC call to use? How to archive transaction to have a proof of sending ...
2
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0answers
47 views

Where can I download the bitcoin blockchain to do offline analysis?

Where can I download the bitcoin blockchain to do some offline analysis. edit: Ideally I'd like to download .txt (or another file extension, e.g. .dat, as long as the contents are unencoded and human ...
2
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0answers
126 views

Proof-of-Stake: How to ensure immutability of the blockchain?

In Proof-of-Work, a miner tries to solve PoW puzzle based on the hash of previous block, such that in case of changing block B_i, all blocks after that (blocks B_i+1, B_i+2, ...) are no longer valid ...
2
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1answer
82 views

How do different implementations of the Bitcoin Cash client know which type of coin they're processing?

TL;DR: Where in this code does the SV client figure out that it's not processing an ABC blockchain? This image prompted my question. There are a couple different mutually incompatible (I am assuming ...
2
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1answer
154 views

Different balances in API block explorers for BTC

BTC.com block explorer shows bigger balance than for example Insight or Blockchair. For example: https://btc.com/1FLDCfr9iG7n6bAdGsqBXmhaLgC4aSze72 https://insight.bitpay.com/address/...
2
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2answers
241 views

API for multiple blockchains

Is there an API to get data for multiple blockchains? Most blockchain explorers already offer an API but I'd like to be able to get information for different blockchains through the same API.
2
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0answers
230 views

Is my understanding of Blockhain Endianness correct?

I know questions on this topic have been asked to death in a number of different ways. I also know that what endian order refers to specifically is dependent on context. What I want are some ...
2
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0answers
162 views

Blockchain explorer for regtest mode

I'm looking for a Bitcoin blockchain explorer that will work in "regtest mode", mostly for demo proposes. Any suggestions?
2
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0answers
419 views

How to delete last n blocks / roll back to specific block number in Bitcoin Core? (Like `monero-blockchain-import --pop-blocks n`)

I have Bitcoin Core's bitcoind running and synced in a VM. Now I want to clone the VM and run one of the various hard forks (such as Bitcoin Cash) in the clone. The plan is to roll back my copy of the ...
2
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0answers
79 views

Question about BIP70 and bitpays recent card top up changes

Okay so bitpay just sent out an email that outlines some changes to their card top-up process. Apparently, they are implementing BIP70 and I am honestly not very familiar with what exactly that is. I ...
2
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1answer
426 views

Understanding a Wallet Restore

This is my first post on block chain related programming so please excuse my ignorance. I find the terminology in the BIP32 and BIP39 specs hard to understand so I'm trying to confirm my understanding ...
2
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0answers
1k views

Is there any blockchain-based mail services available?

According to technology behind the Bitcoin, I'd be interested in using decentralized blockchain-email. Cryptamail was only one I found but they've been told that it is in beta right now but last ...
2
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0answers
98 views

The blockchain lookup speed in a local machine

How to determine the exact required time (seconds, milliseconds) to find a particular block when searching within a local blockchain using address? Is there any way to make a benchmark to study the ...
2
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0answers
269 views

bitcoind verifychain vs reindex

actually this is not Bitcoin but Litecoin 0.13.2 on Linux Mint, litecoind stopped with "bus error" just on start verifying blocks: tail ~/.litecoin/debug.log ... 2017-05-06 21:15:26 Verifying last ...
2
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0answers
144 views

Method to measure "distance" between 2 transaction id's

Is there a blockchain tool/code that takes two BTC transaction ID's and determines a distance between them. It's 2017 and Bitcoin Privacy (aka trying to walk around in the public without a sign over ...
2
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0answers
229 views

Can't access Blockchain.info API using ASP.NET

I am using ASP.NET(VB) to call API Try Dim strUrl As String = "https://blockchain.info/tobtc?currency=USD&value=500" Dim request As WebRequest = HttpWebRequest.Create(...
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0answers
296 views

Is there a robust way to test for a corrupted blockchain?

While running bitcoind I once had the blockchain get corrupted and it manifested as a non-obvious error message which unfortunately I can't remember. I would like to know if there is a robust way to ...
2
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0answers
271 views

How do i loop through all the related address in a given wallet address

I am using bitcoin block chain API, it is possible to get amount sent in a transaction id and the addresses it was sent to. My problem is getting the RELATED ADDRESSES to the address that sent the ...
2
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0answers
420 views

Synchronisation stopped at one specific blockchain

I've successfully been using Bitcoin core for the past months, but since two weeks ago its synchronisation is always stopped at the exact same blockchain. 2 weeks later, sync is behind by 2 weeks. And ...
2
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1answer
1k views

bitcoind crashing due to insufficient memory?

EDIT 3 Bumping my VPS to 1GB of physical RAM stopped the crashing issue... UNTIL said VPS ran out of disc space. I added prune=10240 to my ~/.bitcoin/bitcoin.conf file such that the blockchain file ...
2
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0answers
110 views

Can we know the address list which blockchain API has created?

I am currently using blockchain payment API. This API has created the addresses for receiving payment. https://blockchain.info/api/api_receive Can we know the list of unused addresses this ...
2
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0answers
149 views

Iterating through LevelDB or .DAT files to enumerate bitcoin addresses

I'm looking for a library that can parse either the .DAT files or the .ldb files to enumerate bitcoin addresses. Alternatively, if that can't be done via the standard .dat or .ldb, I'll take a ...
2
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0answers
394 views

How will Bitcoin and the Blockchain scale in the future?

I wonder how the whole Bitcoin blockchain system will scale in the future. Given the fact that the size of the blockchain will grow exponentially (roughly a tenfold every ~3 years, looking at the ...
2
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0answers
105 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. ...
2
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0answers
207 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 ...
2
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0answers
140 views

What restrictions does merged mining place on the sidechain?

What restrictions are imposed by merged mining on the structure or functionality of a side chain (besides it having to use the same PoW schema)? For example, could the side chain have a higher block ...
2
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0answers
186 views

Filter transactions per block 50 BTC or Higher

I'm using the blocktrail python api, to try and display transactions above 50 BTC per block for a visualization project. I think I'm almost there but can anyone help me understand where I'm stuck? ...
2
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0answers
780 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 executable....
2
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0answers
251 views

Bitcoin-qt database for BitcoinJ downloadBlockChain()

I am using bitcoinJ to develop a bitcoin based payment module for my project. I have the complete block chain downloaded/in sync with the network on the bitcoin-qt client. Is there a way I can use ...
2
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0answers
88 views

How can I record block solve times on OSX?

I need to be able to record the times blocks are solved as they are solved. Bitcoin-abe would be nice (overkill, actually) but I can't get it working on my mac. Anyone know of a mac compatible method ...
2
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0answers
668 views

How to use downloaded blockchain on ubuntu?

I am using a fresh install of Bitcoin and have no wallet with coins at this time, and want to use the Bitcoind service in short time (loading blockchain using bitcoind will take days because of slow ...
2
votes
4answers
157 views

What is the meaning of difficulty in Bitcoin mining?

I'm a beginner in Bitcoin and Blockchain technology, so I have a question after reading about the difficulty in Bitcoin mining: What does the difficulty actually mean? I read that A high difficulty ...
2
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1answer
841 views

What is the required input for python-bitcoinlib getrawtransaction command?

I am running a bitcoin node on my machine, fully synced with RPC commands enabled, rpc server live and txindex=1. In the command-line I can run the following RPC call and obtain the information ...
2
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1answer
717 views

Analysis on the Block Chain for Dead Bitcoins

My understanding is that the blockchain is currently 6.5 GB in size and will continue growing at a fairly hefty rate. Has anyone attempted to analyze the blockchain to attempt to determine dead ...
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0answers
27 views

how to do sha256(sha256(modified transaction)) and find z1 and z2 value

hi I tried to get z1 and z2 value but I cant understand. can any one help me with example for finding z1 and z2. or alternate website for 2coin.org example: see this trans. Two identical R value ...
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0answers
22 views

Binance: How to check BTC value by USDT at time of arrival after blockchain disabled it

Let's say that i received an amount of BTC to my Binance wallet like one week ago. How can i know the value of it By USDT at time of arrival. Usually, i was check that from blockchain.com directly ...
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0answers
62 views

Help analyzing this color coded hexdump of the Bitcoin blockchain

Sample of genesis, growth, and current height Sample of the latter part and the end of blk02655.dat. This probably covers parts of the last 10000 blocks. Process here: https://twitter.com/...
1
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1answer
53 views

Suppose crypto is adopted globaly, and 100 years pass. Where would 100 years worth of global transactions/smart contracts be stored?

To my novice understanding the blockchain is stored on all participating computers in the network. is this to say each computer has the entire chain downloaded onto the hard drive? Or do we merely ...
1
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1answer
45 views

Python code error : Hash greater than Target

While trying to run a reference code from GitHUb i am getting an error "Cannot Mine-Hash is greater than Target". As i am just a beginner with coding i am not able to figure this out. Kindly ...
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0answers
29 views

Get/Calculate Address

I'm currently using a program that analyses the block files. It splits all the stuff into multiple .csv files. Is there any method I can do to get the addresses & amount sent/received from tx_in ...
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0answers
28 views

why do i lost my bitcoin on blockchain wallet without forgetting private key?

This is the first time to use Blockchain and send my bitcoin into it. But i was sent into private key wallet address and store it. Next day, when i was login my wallet and say wrong password . So i ...
1
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1answer
21 views

What to look for in Bitcoin-core logfile when something bad happens

About a week ago I was trying to reorganise my file structure with Bitcoin Core, I accidentally moved the file before listing it as a backup so when I opened Core, it didn't work. I tried returning ...
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2answers
73 views

Can I find the address of my Bitcoin in the debug.log file?

I cannot download the entire block chain (I’ve tried four times now and failed) so I can’t replace my encrypted old wallet.dat file into the blockchain and do the rescan to check my coin balance. My ...

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