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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Is verification of a blockchain computationally cheaper than recreating it?

One of the advantages of cryptocurrencies like Bitcoin that is often repeated is how hard it should be to manipulate past transactions. The reason that is often stated is that you would have to re-...
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How is the PRIVATE KEY actually created in the first place?

How is the "Private Key" created in the first place? I understand that once you have your wallet, you will also gain access to your public key and private key... But in order to have a wallet ...
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Method to create P2SH address

I am trying to create a htlc smart contract manually by writing a script and finding the hex using the btcc compiler. Now node A has to create a transaction using that hex and lock money in that p2sh ...
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Doubt regarding hashing function in Merkle trees

From what I read, say in a block, there are 4 transactions. The hash value of transactions A and B are combined together to get the hash AB. Same goes for transactions C and D to get hash CD. Later AB ...
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31 views

OP_EQUAL not working properly

I went to https://siminchen.github.io/bitcoinIDE/build/editor.html to try some bitcoin scripting and I wrote this script: <1PUzZ61FSVTn12CafJC85Vy1ts3BoFcXdU> OP_HASH160 <...
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Is the current hashcash proof of work system vulnerable to attack by quantum computer? [duplicate]

I've been caught up in the post-quantum cryptography scene for a little while now, and understand that the RSA or ECC cryptography inherent in a cryptocurrency network can be easily broken by a ...
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42 views

Is this a collision attack or a 2nd-preimage attack?

This question revolves around Bitcoin Optech newsletter #51 (1) and an email thread from the bitcoin-dev mailing list (2). I asked the same question in a reply-email of the newsletter and the response ...
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What happens if I send a XRP transaction to a blank TAG when I was supposed to send to a specifc TAG?

I sent XRP to a blank TAG while I was supposed to send to the éxchange's TAG. The address is the one from the exchange but the TAG was left blank. The exchange says that they can't recover the money. ...
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19 out of 24 words of BIP39 passphrase (brute-force last 5?) [duplicate]

I have managed to lose 5 words of my 24 word Ledger Nano S recovery phrase. I have words 1-19 but I am missing words 20-24. I have significant holdings on the wallet so would very much like to recover ...
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13 views

Public key vs Bitcoin address [duplicate]

As i've read on many websites and papers, the bitcoin address is made by hashing the public key. And i've read that that's done because we don't want the public key to be public until money is spent. ...
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1answer
35 views

How chaining the blocks protect against altering data?

I am confused with the block chaining, as i know a block header contains a reference to the previous block header hash with the merkle root and other fields. This header hash is related (computed) to ...
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What is preventing me from simply constructing a hash that's lower than the current target?

I just started learning about Bitcoin, and something I can figure out is why miners have to use a random process (hashing a nonce) to get lower than the target. For example, if the target is ...
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38 views

How difficult is it to confirm a Bitcoin Block?

If I have done the math right to come up with this hash, to confirm a true block and this is a confirmed hash. You can look it up here Bitcoin Block #570240 ...
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Hash rate of the average PC/Top end PC [duplicate]

Hi I was wondering if anybody had any idea about what the hash rates are like with PCs released fairly recently. I'm sort of looking for figures to use for an average user if they wanted to use their ...
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41 views

Signature digital algorithm in bitcoin, to what will it change in the future?

in follow-up to the question: 85202 There, @Ugam Kamat wrote ""ECDSA is the first thing that can get vulnerable with quantum computer. signature will need to move to post quantum world much before ...
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110 views

ScriptCode field in P2SH-P2WPKH BIP-143 Test Vector

I'm trying to understand the meaning of scriptCode in the context of spending a P2SH(P2WPKH) UTXO. I've already read the following answer to a similar question, but it does not fully address my ...
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How may bitcoins hash algorithm be secured in the future from quantum computing brute forcing?

Other threads already answer very clearly that quantum comps could easily "break" /attack bitcoins chain. Now: Are there any ideas among the bitcoin devs circulating out there, how to save bitcoin ...
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38 views

Uniquely identifying a UTXO

I see two ways: Txid + index Txid + script hash Pros of the txid + index: Simple and short Cons of txid + index: It relies on array iteration being deterministic and all third party ...
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19 views

Swift implementation of bitcoin transaction creation

Is there a well known and widely used Swift implementation for creating raw Bitcoin transactions and getting their hash (SegWit and Non-SegWit) of signing? If not, is there a reference document that ...
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60 views

Hash rate : Algebraic Equation

I recently made a post on stack, Calculate hash rate in IOS, in hopes of deciphering how the hash rate is calculated when benchmarking performance. The reason I wanted to do this is to compare against ...
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1answer
68 views

where in the source code is the the proof of work checking the blockheader hash and nonce?

Where in the source code do we check whether hash(blockheader*nonce) < Difficulty In fact, the line I found is as follows: https://github.com/bitcoin/bitcoin/blob/v0.17.0.1/src/pow.cpp#L87 My ...
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152 views

How specific are ASIC's design? Can they single hash SHA256?

I understand that Bitcoin's ASICs are a highly optimized piece of equipment and, therefore, are also very specific. My question: are they able to do a single (or triple?) SHA-256 hash at all? And, ...
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Trying to understand why hash value is more secure from hash algorithm

I am currently studying in college in the US and was actually curious about bitcoin and cryptocurrencies as a whole. I started looking on free university sites like Stanford university and New York ...
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30 views

How does transaction authentication between buyer and seller look for?

I am new to cryptography and would like to understand how a digital signature works between a buyer and a Bitcoin seller. How does transaction authentication between buyer and seller look for? Please ...
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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 ...
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246 views

Bitcoin-core how to get all transactions hashes?

Please, can anyone help me how to get all transactions hashes? How to browse all the transactions hashes used in blockchain? P.S. How simply get a list of all transactions IDs (as a simple text list) ...
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Hashing Transactions for Mining

After reading that Mining involves Taking a root hash of a transaction and combining that hash with a nonce it is required to find a number that is equal or below the given target, i was wondering if ...
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1answer
56 views

Create master public key after HMAC-SHA512

I have that result after hash_pbkdf2 5B56C417303FAA3FCBA7E57400E120A0CA83EC5A4FC9FFBA757FBE63FBD77A89A1A3BE4C67196F57C39A88B76373733891BFABA16ED27A813CEED498804C0570 left 256 bits are: ...
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49 views

Newly generated coins

New to BTC world so my question is how and what can I do with newly generated coins what's the process and how to see balance of that in wallet? Can I send those to paper wallet
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Is it possible to accurately map hashing power to network size?

Let's say we have a network with n nodes in it. Is it possible, when the hashing power of the network is calculated after a proof-of-work, to accurately estimate n with an algorithm taking the ...
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35 views

in transaction, what is 'hash' data?

i'm studying Bitcoin: A Peer-to-Peer Electronic Cash System Satoshi Nakamoto and this paper introduce a transaction model. (above picture) but i don't understand what is 'Hash' means exactly i ...
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48 views

How to determine right address from address hash

I'm using private libbitcoin server and libbitcoin explorer. When I use bx fetxh-transaction, it returns something like: I'm trying to figure out, how to get right address from address_hash. When I ...
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Electrum's “script hash” form with NBitcoin?

I've come across how scripts are hashed in the electrum (stratum) protocol implementation by looking at the docs. I'm using NBitcoin, and I've tried to generate this hash from a segwit address, first ...
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98 views

SHA256 vs RIPEMD160 in SegWit

In Pay-To-Witness-Public-Key-Hash (P2WPKH), the RIPEMD160 hash function is used to hash the public key of the recipient in the locking script. On the contrary, Pay-To-Witness-Script-Hash (P2WSH) uses ...
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19 views

Merkle hash tree

Does the Merkle hash tree always have to be a binary tree? If not then what will be the advantages if it is ternary, tertiary…or anything else?
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Does hashing of bitcoin addresses cause collisions? [duplicate]

There are 2^256 possible public keys. We generate bitcoin addresses by hashing these public keys using SHA256 and then RIPEMD160. Now, since 160 < 256 won't there necessarily be collisions - ...
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141 views

How to convert a bitcoin address to the respective hash160 using bash?

I want to convert a list of bitcoin addresses to their respective hash160 values as illustrated using bash :
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56 views

Why is Target < Blockhash?

I am currently trying to validate a blocks hash against its target in python3: This is a block in the Blockcypher testnet, and I am using this formula from the Bitcoin Wiki. block_hash = '...
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1answer
57 views

Sorry newbie, I dont get the PoS block creation, to much contradiction

I am sorry for the repeat question but I cant find a clear answer. Most of the time PoS isnt explained in detail (only explaining the advantage) and a lot of sources contradict each other and now I am ...
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I am just wondering what are the methods which can hide all the transactions and also able to validate transactions in an block chain?

I am new to block chain and was looking at how block chain work mainly proof of stake based . They check validity by going through all the transactions which is something concerning as everyone can ...
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Why is the nonce bruteforced from 0 to n while mining?

bitcoin noob here. I was wondering why is the nonce increased from 0 to n while searching for a blockhash? Why not start at some other integer > 0 for example? My background is in ethereum-dev, so ...
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27 views

Can't we change the block data instead of a nonce?

In the process of solving a hash puzzle, isn't it possible to change the transaction data instead of changing a nonce?
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184 views

Natural Language Processing and Blockchain?

This question is about one of the applications of the Blockchain in Artificial Intelligence. I am not very familiar with Natural Language Processing and I see that there is a Blockchain platform ...
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181 views

Getting transaction id from raw transaction of a multisig address

I am able to get the tx id (or transaction hash) of almost any transaction but the one where the script starts with an "OP_O" (which is, I think, the null dummy introduced here https://github.com/...
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112 views

Estimated number of hashes

This is not a duplicate of previous, similar questions I've read on StackExchange, since none of those questions, nor the answers, go into the difficulty theory, as espoused on the Bitcoin Wiki. ...
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451 views

Checksum vs. Hash: Differences and Similarities ?

What are similarities and differences between a "checksum" algorithm and a "hash" function? Can they be used instead of each other? Or their usage are different? For example, for verifying the ...
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retrieving an original data from a hash: is it reliable?

Normally, one of the purposes of hashing a string (such as a transaction) is summarizing the data to save the size because of the space limitation. If this proposition is true, now assume we need to ...
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1answer
71 views

How to protect the latest block in block chain be tampered?

We know for each block in block chain, it has the previous block header hash which make the block be tampered become difficult. If the block is tampered, then all blocks after this tampered block need ...
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How come Merkle tree is more efficient when tree branches are not stored in blockchain?

Suppose we have 8 transactions in a block X as follows and we know every node's hash value of the whole Merkle tree (that is, including intermediary nodes such as 45). Then if someone claims ...
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275 views

General private/public key generation

Not sure if this is the correct forum to ask, but I couldn't find a general one for all cryptocurrencies I wanted to get an idea on how the whole cold-storage private/public key generation works for ...