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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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570 views

Bitcoin - Is the <pubKeyHash> in scriptPubKey already hashed?

In Bitcoin protocol, to set the output of a transaction you need a scriptPubKey which is in the following format. scriptPubKey = OP_DUP OP_HASH160 <pubKeyHash> OP_EQUALVERIFY OP_CHECKSIG Is &...
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1answer
42 views

How does Bitcoin utilize cryptography and secure hash algorithm (SHA) to link records in the blockchain?

I am wondering how Bitcoin uses cryptography and secure hash algorithm such as SHA256 to link the records in the blockchain. And if possible I think it will give me a better understanding if there is ...
3
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1answer
1k views

Longest unconfirmed transaction?

I recently tried to make a transaction with coinbase. In a hurry I put no fee though. It's still unconfirmed and blockchain.info doesn't recognize my hash. But my btc qt wallet is debited. My question ...
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32 views

Blockchain.info explorer doesn't recognize my hash

Blockchain.info doesn't recognize my tx. Can someone explain this. My wallet is debited. The transaction is unconfirmed too.
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1answer
25 views

What would be the effect on the number of leading zeros hash generation if bitcoin increase its nonce size from 32 to 60 or 100 bits?

If Bitcoin increases its nonce size from 32 bits to double or triple the size, how will it affect the speed of getting the right hash with the required number of zeros?
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1answer
30 views

How to transfer hash power from one pool to another

Is it possible to transfer hash power from one pool to another? If yes, how?
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2answers
40 views

How do more leading zeroes make it more difficult to find a block?

A couple of articles describing the process of mining do say that the more miners are in the network, the more 0 numbers are included in the encoded hash of the particular block. I cannot find an ...
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2answers
60 views

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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0answers
51 views

How get the public key to hex script? like command decodescript of bitcoin core

If I want to recreate the command decodescript of bitcoin core? how is the process for decode the script P2PK? So I'm writing for personal exercise the Bitcoin script decompiler, form moment I have a ...
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1answer
16 views

How are the requirements of the hash for mining a new block determined?

How are the requirements of the hash for mining a new block determined? Is it published or a message is sent?
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0answers
50 views

How to sign an Altcoin transaction manually with 2 inputs and 2 outputs

So i'm working with the altcoin denarius which has the following raw TX structure. This is a transaction I am try to sign: Original: ...
2
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1answer
625 views

Can't find correct z1 & z2 for transaction

I've been trying to understand the issue and repeat Willem Hengeveld's answer, but I think I'm failing at getting correct script for hash. I'm looking for this transaction, my scripts are: ...
2
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2answers
139 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.
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1answer
145 views

Hash-based crypto-currencies?

What are the most famous crypto-currencies which use repeated hashes as proof-of-work? What are the other proof-of-work methods?
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1answer
780 views

BTC Hash-Rate API

I'd like to get hash-rate of BTC from OKcoin' API(GET /api/v1/charts/:type) here is OKCoin's API web site. How can I get information from here is OKCoin's API web site. python gets = requests.get("...
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0answers
35 views

BIP32 HD Wallet vs HMAC vs Hashing

I've been working on a website which will be caring out various cryptographic operations. On the website users can post Ads. Each Ad has a monotonically increasing unique ID. For each Ad, I would like ...
3
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2answers
679 views

Checking the Merkle Root for Block #100000

The below text is copied from the Bitcoin Developer Reference at bitcoin.org: If a block has three or more transactions, intermediate merkle tree rows are formed. The TXIDs are placed in order and ...
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0answers
31 views

Bitcoin Module - Hash512-EVP_ByteToToken

Is there any standalone software modules created which allow the user to complete the following: 1. Enter in passphrase 2. Enter a given salt 3. Enter the number of rounds I am looking ...
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1answer
45 views

How many hash calculation is needed to reach one BTC?

What I am asking for is a formula and it's source of numbers to put in there and calculate how many hashes must be calculated to get 1 bitcoin today(or every other day in future)? For example, if I ...
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1answer
16 views

When changing transaction data in a block change the hash of previous block?

If i only manually change the data on the block without touching/modifing the already calculated hash, then hash on the block its still valid because its already saved and was not touched ... so, ...
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2answers
687 views

How does changing transaction data in a block change the hash of previous block?

I am reading this article, within which it mentions that "Imagine this for a second, a hacker attacks block 3 and tries to change the data. Because of the properties of hash functions, a slight ...
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3answers
1k views

Why is it impossible to modify a transaction in the blockchain?

Many pages (including Wikipedia) say that it is impossible to modify a transaction which is already in the blockchain included. But why is it so difficult?
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1answer
43 views

How exactly does the network know if the miner has put forth a valid proof of work?

If all that the miner needs to do is find a hash with a certain number of leading 0's of the block's header, couldn't they just find a random hash with the required number of 0's that isn't ...
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1answer
55 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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3answers
9k views

What is the approach to calculate an Ethereum address from a 256 bit private key?

For a given private key generated by MyEtherWallet, I would like to see I have the tools to independently arrive at similar results. Wrote a wrapper around Keccak to accept both hexadecimal and ...
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2answers
197 views

What are the unnamed parts of the segwit/bitcoin cash raw tx shown and how do I get them as shown?

There are three parts to this. Shown here. Part 1. This string is found at the final form of the raw tx: ...
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3answers
502 views

Why is HMAC-SHA512 used on root the root seed to create master private key and chain code in HD wallets?

The process is depicted in this picture. Specifically, given that the root seed was derived using PBKDF2 (with 2048 rounds of hashing with HMAC-SHA256 already), why do we undergo an additional pass of ...
3
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1answer
372 views

Duplicated hash values in mining reward

This transaction is contained in two MainChain-Blocks: https://blockchain.info/tx/e3bf3d07d4b0375638d5f1db5255fe07ba2c4cb067cd81b84ee974b6585fb468 On Blockexplorer there is a note of this anomaly: ...
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1answer
912 views

The warpwallet challenge 2

here you can find a public challenge aimed to brute force a brain wallet private key, derived from 8 char long [a-zA-Z0-9] passphrase with a salt of "a@b.c". Is it possible to adapt an hashing ...
2
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2answers
3k views

Generate private key from a bip-39 seed phrase?

I'm able to generate a new private key and associated public addresses using bitcoin-core, but what I really want to do is generate a new private key from a 24 word seed phrase. I'm not sure how to go ...
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1answer
168 views

How do I double SHA-256 the header of block #59,500?

I'm not sure how to combine all of this information. https://blockchain.info/block/00000000096af43105123c499521e1d131d172e7e1bf2ed0843290a921f1f6a7 Version 1 Time Bits 470771548 (is this the right ...
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2answers
377 views

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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1answer
26 views

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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1answer
841 views

How do I get hash to verify transaction?

If I have the public key and signature for a transaction how do I get the hash value that is used in verify(hash, sig, pubkey). I want to know how to work backwards from a raw transaction to get it, ...
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0answers
33 views

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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1answer
18 views

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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2answers
116 views

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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1answer
40 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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0answers
20 views

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 ...
2
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1answer
60 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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2answers
481 views

What would happen if two public keys had the same Base58 hash?

If two different public keys had the same Base 58 hash, what would happen? Could one key spend money in the other account? What would happen to the monies received by the shared base58 hash?
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3answers
2k views

What will happen when SHA 256 needs to be replaced?

MD5 used to be the hash algorithm. Everyone loved it, but now, not so much. What will happen to bitcoin if flaws are found in SHA256 in the future?
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2answers
54 views

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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1answer
59 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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0answers
32 views

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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0answers
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. ...
1
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1answer
36 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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3answers
414 views

Getting the wrong txid for coinbase transactions

I'm trying to hash transactions to get the txid. I get the hex values from blockchain.info. I get the correct hash for all transactions except for the coinbase when I hash it twice. Is there something ...
2
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2answers
280 views

What is Bitcoin's “genesis hash”?

From Lightning Network documentation: Used in several of the BOLT documents to denote the genesis hash of a target blockchain. This allows nodes to create and reference channels on several ...
5
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2answers
886 views

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 ...