Questions tagged [hash]

This tag should be used for questions related to hashes. A hash is the output of a hash function, a function which .is a mathematically reproducible but irreversible process that takes in an arbitrary length input and produces a fixed length output. The same input will always result in the same output. Hashing is central to Bitcoin mining as well as the generation of Bitcoin addresses.

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Looking for feedback on (Browser-based) Blockchain Simulator

I have created a Blockchain 'simulator' in JavaScript, for the purpose of helping explain how the technology works. It is complementary to a website I have set up years ago, where I attempt to explain ...
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cannot generate bitcoin first block

I have download bitcoin source and change genesis in regtest. and i try to generate 1 block by command ./bitcoin-cli -generate 1 it does not show any mining block. i try over 10 times but it is still ...
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How does a blockchain relying on PoW verify that a hash is computed using an algorithm and not made up by a human?

How does a blockchain verify that the hash provided (the one with the leading zeros that is supposed to be unique, computed using lots of processing power) is indeed unique and that it wasn't just a ...
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Is the block header in stratum protocol double hashed?

I'm trying to understand how the block header is done when mining in a stratum pool. Should the block header be hashed once or double hashed ? the block header consists of the version, previous hash, ...
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What exactly happens to leaves when forming nodes?

If you hash TXIDs with sha256 twice, you get the leaves of the merkle tree. As far as I understand the two outputs of the TXIDs are concatenated / paired. What does that mean? Are they added together?
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BTC on blockchain

I see my Wallet address on the Blockchain but it says spent and what does that mean? It did not arrive to the wallet i sent it too! I need it to be located and returned or sent to the wallet i gave.
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RegTest Genesis Error

how to generate regression test genesis block ? i saw in bitcion nonce is 2. but i generate from GenesisH0 it not showed nonce 2. for other altcoin i saw nonce is 0 why ? how to generate it ? python ...
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Bitcoin leading zeros as difficulty [duplicate]

Does it necessarily have to be leading zeros that determine the bitcoin difficulty, is it possible to use lets say 9 zeros at the end of the hash to determine difficulty as well.
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How to generate a coinbase transaction?

I am creating a miner in C++ for solo mining, and am struggling to create the proper coinbase transaction. Say I have a bc1 address, like bc1qfc7fameteuguetm0kfzypnvf2ju6wppdvj6tkc , what would be and ...
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Regardless of how bad it is for the network, wouldn't mining an empty block be signifigantly less work? [duplicate]

A block contains the previous block's hash, a nonce, and series of transactions. That information needs to be hashed until the block's hash meets the number of leading 0 requirement. My question is, ...
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What are the sources of entropy in blockchain

I have little understanding of what entropy is and its specific role in blockchain. What I understand is that they're sources of randomness. From that, I'm able to infer these sources in blockchain ...
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how to hash block header in c++

I want to hash a block header in C++ but dont know how. Im just using a test block at the moment, so that I know what the expected outcome is. https://www.blockchain.com/btc/block/669892 I have a ...
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How do I hash header block with C++

So im trying to hash a header in C++ and I am having some trouble. I have tried different libraries (cryptopp, openssl) cant seem to hash the header correctly. This is the block which I am testing: ...
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How is the Target Hash determined?

So, I understand how the amount of leading 0's are calculated, but how is the hexadecimal that come after the leading 0's calculated? For example, the previous mined blocks hash was ...
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How does solving a block work in relation to the first letter/number after the 0's?

I did a terrible job of explaining it in the title so I'll explain here. Say the target hash to solve for a block is 00004aef... etc. does that mean that you can't solve the block if you get 00005fad (...
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Calculating P2WKH nested in P2SH addr/redeem script hash from pubkey

My calculation of the hash160 doesn't seem to be correct - what are my sins? Tx spending the input: https://www.blockchain.com/btc/tx/d490cc0a5b9799e09b02dd4b20a6d7ca297c09c425983efc13b382f6023d0376 ...
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3answers
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ASIC-Resistant Proof of Work

Bitcoin uses a Proof of Work algorithm that makes it the perfect victim of ASIC mining. As a result, it is not very decentralized (more than 50% of Bitcoin's hash power is concentrated in China and ...
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How difficulty increases to get the lucky hash in blockchain? [duplicate]

Currently first 19 zeros are required in bitcoin block hash which has become very hard. How this zeros are being controlled to increase? If it is dynamic what are the factors which has influence to ...
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What is the practical link between the hashing power in the bitcoin network and its security? [duplicate]

Several books claim that as the hashing/computing power increases, the bitcoin network is securer. How can a non-techie sees that from a practical standpoint?
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Does bitcoin mining pool hash randomly and separately

When it comes to hashing does each mining entity use total random seed for each of their hashing function or do they have a range like " Im gonna cover from 0 to 500, and you cover from 500 to ...
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Three different HEX having same wallet address how possible?

HEX1: 1111111111111111111111111111111111111111111111111111111111111111 public key: ...
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With the right technology, could the entire blockchain be rewritten?

Imagine that someone had access to an alien super computer such that they could mine any block in nanoseconds. At that point, could that person create a chain with the same BTC genesis block, generate ...
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Stealing a correct hash because of an invalid block

Suppose that a miner find the right hashes but involuntarily or by malicious intention then create an invalid block, like trying to double spend a transaction My guess is that the moment this block is ...
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Will a recursive sha256 run over all 2^256 inputs before a collision?

Will a recursive sha256 run over all 2^256 inputs before a collision? Here'a a python program showing my question - will this loop for 2^256 times - given endless memory or will it terminate before - ...
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Adding instead of concatenating hashes in Merkle trees

Why aren't the hashes combined using a commutative operation such as addition instead of concatenating them? Any possible vulnerabilities or security flaws? thanks for your time and efforts.
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Bitcoin Core ZMQ “hashTx”

Bitcoin Core ZMQ messaging system has hashtx along with 4 other topics. But nowhere it is documented whether the transactions that comes from hashtx are confirmed transactions which are added in a ...
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Is a timestamp in bitcoin different than just the “stamp of time”?

In the "References" section of Bitcoin's whitepaper, Satoshi Nakamoto points to three papers that serve as inspiration for digital timestamping. When you read those documents it is clear ...
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Why number of zeroes in bitcoin hash is increasing? [duplicate]

I know currently to mine a block there needs to be 19 leading zeroes in the hash, but why is this number increasing?
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1answer
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Calculate block hash is different in regtest?

I'm able to calculate the block hash in mainnet and testnet, but I don't get the right hash in regtest. I mint +3000 blocks and I get the block with height 3000 bitcoin-cli getblock $(bitcoin-cli ...
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How do bitcoin verifies block hash after new hash have been submitted by Miners? [duplicate]

I want to know how at the end of Bitcoin server block hashes are verified after it has been submitted by a miner. Do they already have a previously calculated block hash DB or something else? I m new ...
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How many transactions are there in one block

What I understand: When a transaction is made , miners compete to validate it and create a hash . If one miner creates the hash and more than 51% of miners agree on the validity .Then the a block is ...
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1answer
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What would be an example for an insertion into the blockchain?

I'm reading the paper The Bitcoin Backbone Protocol: Analysis and Applications. On page 21, definition 8 reads: An insertion occurs when, given a chain C with two consecutive blocks B and B, a block ...
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Is there a CUDA binary to convert a brainwallet string to a BTC address?

I am looking for a CUDA program which will take a single argument, a brainwallet password, and output a BTC address. After reading through several threads on how to convert passwords to public keys, ...
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College Economics Student in Support of Crypto Looking for Live Hashrate Data

I am a college economics student doing a Thesis project in support of the long term viability of Crypto. Does anyone know where I can get live Hashrate data for free or for sale? I appreciate it - ...
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What will happen when a collision in SHA256 be found?

Would the protocol migrate to another Hash Algorithm inmediatly? What would be the next? SHA3 or BLAKE 2?
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Parsing transaction hash from rawblock data

I got block raw data next url https://blockchain.info/rawblock/00000000000000000002447735c7723ee9188322c0938e6587866a4458b9135f?format=hex Can I find transaction hash in url used python?
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Can I get all block header data like the SPV node?

It hasn't been long since I studied Blockchain. I only need header data, not all block data, for study purposes. As far as I know, the SPV node stores only the block's header information. Can i get ...
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Padding the blockheader in sha256

The block header size is 80 Byte (640 bits) so we must pad it to a multiple of 512 (In our case to 1024) like this: (blockheader in binary)+1+00000.....000+1010000000 where "1010000000" is ...
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Is that proved that for each block there is always nonce value which will make block hash to start by n count of 0

Sorry for the obvious question, but I'm looking for a mathematical prove. Block header is calculated as a concatenation of the following values. Version hashPrevBlock hashMerkleRoot timeStamp Bits ...
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Solution to the same TXID from 3 different client

Someone sent me some bitcoins.... then I had some other clients sending me the same txid that they also made a payment, but I received only one payment.
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1answer
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Calculate Z from r and s

Can anyone explain me any clearly answer or code in python with examples how we can calculate Z value from r and s and inputs outputs order ?? I search in google and youtube and i not saw any ...
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Why do these 2 blocks have the same hash for the block reward? [duplicate]

Could someone explain to me that why do the hashes of the block rewards in these 2 blocks be the same? https://www.blockchain.com/btc/block/...
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How do miners earn partial bitcoins?

I know that the miner who has the hash matching with the bitcoin's root software gets to stamp the block and put it onto the blockchain (correct me if I'm wrong). Accordingly, that miner takes the ...
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Why do miners need a nonce if the timestamp changes the hash of the block?

As the title says. If the timestamp is constantly changing with every guess, why does the miner also include the nonce? Is it because they're mining too fast for the timestamp to change?
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What does the version number in the blockheader represent

While looking up how a block get mined I stumbled over the version number in the header - which is used to "keep track of changes to the protocol". But even in the last 5 blocks of the chain (at the ...
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How does the daemon get a transaction via a hash

I am wondering how the daemon gets the transaction data from just a hash. I'm NOT asking how i can get it, i know i can get it via the rpc, i am asking how the daemon does it behind the scenes. Does ...
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How to find Reused R values

I use software from https://github.com/ca333/rng-scanner , I try to find r that is reused. from the software I found results Bitcoin Address : 1GQdrgqAbkeEPUef1UpiTc4X1mUHMcyuGW In Input NR : 141 ~ ...
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Why are hashes base16 (hex) encoded rather than base58 encoded?

BTC sha256 hashes are hex encoded (as sha256 spits out bytes not a string), why is this? Surely using base58 would be more efficient as would use less space (would output a shorter string)
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Get invoice amount from payment request - LND REST API

I'm using the REST API of my LN node to generate and pay invoices. I would like to know how to get the invoice amount/value in sats from the payment request I receive. I found this : https://api....
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How to generate the hash of public key in Bitcoin [closed]

I'm trying to hash the public key with SHA256 and then ripemed160 and get the hash. but it gives the wrong hash Public key: 2b4632d08485ff1df2db55b9dafd23347d1c47a457072a1e87be26896549a8737 Hash ...

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