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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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Bitcoin Mining Adder optimised with hardcoded constant

I've been reviewing Intel's paper Bonanza Mine: an Ultra-Low-Voltage Energy-Efficient Bitcoin Mining ASIC where they claim to have a completion adder optimised with a hardcoded constant that is unique ...
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Repeating identical outputs in bitcoin transaction

I am building a script that is indexing all bitcoin transactions in real time with all their details etc. But I am looking here at this transaction - https://www.blockchain.com/btc/tx/...
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How is mining the exact same hash on every computer avoided?

How does the mining clients make sure that the seeds are not the exact same computed on every mining rig in the world with for example a GTX 1080 with the same speed? So that it is not the quickest ...
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Is it correct to refer to hashes found through proof of work as "proof of work numbers"?

I've seen come commentators refer to 'proof of work numbers'. I suppose these are the hashes found through proof of work, but not entirely sure. EDIT** Regarding where I got the 'proof of work numbers'...
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2 answers
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What is the difference between a 'hot' and 'cold' wallet

Problem I don't understand the difference between a 'hot' crypto wallet, and a 'cold' crypto wallet. Assumptions My understanding of blockchains is that they use public/private cryptography in order ...
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Is the winning hash the same as the nonce?

Is the miner is trying to solve the nonce or a winning hash? "The SHA-256 hash of a block's header must be lower than or equal to the current target for the block to be accepted by the network.&...
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What does SHA256 hast must be lower than current target?

I'd like to ask if someone can help explain this definition found on https://en.bitcoin.it/wiki/Target "The SHA-256 hash of a block's header must be lower than or equal to the current target for ...
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1 answer
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How often does target hash change and how to find it?

So basically I was researching target hash and trying to figure out how I can find it. I know there are posts out there that have said that Bitcoins target hash is a 256 bit number with 32 bits of ...
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How can i achieve this signature?

I want to make a signature in bitcoin where the nonce and private are the same. For example, the private key is 0x1000 and the nonce for the R value is also 0x1000
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1 vote
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What needs to be changed in Bitcoin if SHA-256 is broken? [duplicate]

I come up with a little bit "catastrophical“ question. I declare that I understand the degree of improbability of such a scenario in our lifetime, but I would still be interested in your opinion. ...
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Mining against candidate block hash or previous block hash? [duplicate]

When mining...; a) Is the block header hash of the candidate block used b) OR the block header hash of the previous block + noonce used? If it is a), which I presume, is it then correct that the ...
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2 votes
1 answer
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Bitcoin transaction inquiry

if suppose a someone offers a prize for anyone that can solve a specific challenge, how will the solver make sure that he/she collects the reward? Does the solver need to send the solution directly to ...
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1 answer
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Q's about P2WPKH

I got some btc in testnet, here are the outputs. this is the UTXO that i get my btc { "value": 17.24756333, "n": 1, "scriptPubKey": { "asm": "...
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One address 2+ private keys. Bitcoin future

Since bitcoin uses cryptography algorithms to create private and public keys there is a possibility it could repeat. Person 1: L54w...KraG -> bc1...kq4 Person 2: L3mV...JU8G -> bc1...kq4 So ...
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How to decrypt private key bitcoin core?

I'am Wahyu. I found my old file on the flash disk which contains the encrypt private key, public key and address. can i get my bitcoin core account back? I created a core bitcoin wallet in 2012. if ...
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What actual steps are required to calculate a block's header hash?

From my knowledge a header hash will be calculated like this: serialize all header fields, including "the nonce" hash the serialized header once hash the hashed serialized header again ...
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Calculation of the hash of a block

Please help me to calculate the hash of the block 722460. I have this block header: "hash": "00000000000000000002b73f69e81b8b5e98dff0f2b7632fcb83c050c3b099a1", "...
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How many times and where exactly is ECDSA used in Bitcoin?

I'm currently a little confused about where exactly ECDSA is used in the transaction process... some resources seem to say it's used once, whereas others seem to say it's used three times. Which is ...
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Want to verify previous block hash and prove of work

I want to verify several random blocks and check if there was prove of work really found. I need it for some reasearch reasons. I have downloaded the blocks historical info and there are only hashes ...
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1 vote
1 answer
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Stumped on finding checksum for 12 word Bip39 mnemonic

I read Pseudo code to find Bip39 checksum? and followed the steps outlined by the answer and arrived at the correct checksum. But when I went to try it on a 128 bit entropy that were all 1s: ...
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4 answers
235 views

How to forge a signature with fixed Z value

I want to forge a signature with a fixed z value, what is the formula to do that
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1 vote
2 answers
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why do we need to hash before we use a private key to digitally sign a transaction? isn't just using a private key enough?

why is a hash needed for digital signatures? isn't it redundant since the point of hashing is to ensure contents are not tampered with , which the digital signature can do as well (on top of ensuring ...
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Invalid transaction. Error: TX decode failed. Make sure the tx has at least one input

I'm using bitcoinlib for python to create a transaction and send it but I'm getting the following error: Funds not sent, exception error: Error connecting to blockchair on url https://api.blockchair....
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-3 votes
2 answers
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How to derive the Private key when the two the nonces are k and k*2

Is the same private key using k and k*2 respectively in two different signatures vulnerable? If yes How to calculate the key in this case Here is an example, Both signatures are valid and the nonce of ...
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What time of encryption from late 2000s contains house, smileyface, squares, letters and numbers?

Have a encrypted password or key typed to paper, i vaguely remember doing it, not sure if note pad was involved or some site , i remeber something about sha-2 , and sha- 256, and why i should use one ...
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1 answer
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What determines the size of a hash during mining?

I have been struggling with this quite a bit. From what I understand is that a miner generates nonces to find a nonce that is smaller than the target hash. However, how does one determine the size of ...
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How to get list of Bitcoin Block Hashes by Block Number?

Suppose I want to obtain the block hashes for all Bitcoin blocks numbered 1 through 50,000. What would be the best way to obtain this information? I could write a web scraper to pull it off web-based ...
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can i diy an asic miner?

Iam interested in mining bitcoin so Iam wondering if I can get a pcb for hashing and bring asic chip that algorithms are sha-256 and stick them together with some other electronics and have a control ...
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3 answers
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Why miners looking for zeros?

I am trying to understand how miners work. Is it true that miners are looking for a number of zeros because if they needed to find the complete hash they will be able to see the content of the ...
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1 answer
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I've built a bitcoin miner and mined. Now what I do?

I've mined bitcoin to test and understand cryptocurrency better. Which generated this hash 00000431fb66ed96815b3829e975c2235a64b9a646c0bd1cc526dc1727c1f16b(nonce value of 300712) What I do with this ...
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1 answer
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Detecting BTC transaction hash data: help

please I need some help in reading the hash data correctly. Given below transaction of total value btc 1.55821903 https://www.blockchain.com/btc/tx/...
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BTC invalid transaction: double spending attempt?

I'm writing because I need some help in understanding the below hash data. Thank you. https://www.blockchain.com/btc/tx/976e6d64a4c98cf15ac917b98a04333f896b7cd15c1f2fdfb18f6fee668b670c Is it a double ...
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2 votes
1 answer
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Size of seed used in murmur3 hash BIP0037

I'm trying to implement a seeded murmur3 hash using the bip37 standard for use in bloom filters. In hash.cpp in bitcoin core, the seed is an unsigned int value. However my understanding of bip37 to ...
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1 vote
1 answer
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What exactly is signed in "prev_out"?

What is signed by scriptSig? I use my private key to sign data from the unspent transaction? I sign the "prev_out" object? I read that the signature in "prev_out" is there to ...
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More than one possible nonce [duplicate]

Assuming currently we need 19 leading zeroes in the hash. Assume that for a block, minimum nonce possible for getting 19 leading zeroes is 12300, but a pool/miner returns 32330 as a nonce (which also ...
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2 votes
1 answer
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What hardware do pool operators use for calculating the hashmerkleroot?

I've reviewed the response here: How do pool operators do their hashing? and acknowledge that the ratio of hashing required by pool operators is incomparable to the miners. I still wonder what ...
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1 answer
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Changing the blockchain requires more than just recalculating all hashes..?

New here! I read this everywhere - "To change some data in a blockchain, the malicious user will have to recalculate hash for every block starting from that particular block". My doubt is - ...
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1 answer
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Is there a list of processes within Bitcoin that use hash functions?

Hashing within Bitcoin is done in several different areas of the code. EG: We have the SHA-256 mining algorithm, the Merkle tree hashing, and I believe double hashing within certain areas (SHA-256D). ...
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For a block containing 'x' number of unverified transactions, how many SHA256d hashes are performed to obtain the hashmerkleroot?

I've been trying to understand this for a few days now. I understand that the hashmerkleroot is the root node of a fully perfect binary tree. I also understand that the sha256d hashes would be the non-...
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1 answer
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What is the difference between hash-target and the previous hash? [duplicate]

Is the target that the requirements have to meet a number that is set by the network that is always the same, or is the target the hash from the previous block?
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Is the block header the data that gets hashed or is it the info of the transactions that get hashed? [duplicate]

I just need to know what is the data that gets hashed. Also if the nonce is put from the beginning or if it's only out if it doesn't meet the requirements of the target. Thanks.
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elderly mom transfrred bitcoin out of coinbase but doesn't know where it went ... have identifiers and hash stuff

My mom is and she transferred bitcoin out of her coinbase account which we finally regained access. She does not know where she transferred it to, i.e., a wallet, or other account? We have the ...
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1 answer
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What parts of a block, other than the nonce, can a miner vary

What are the list of all the variables whose values that the miner can cycle or modify to get a valid hash for this block (with very high probability) ? The only one I am aware of is: Nonce - 4 Bytes....
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Why tagged hash repeat the tag twice?

I noticed that the hash message for the tagged hash in BIP340 is prefixed with SHA256(tag) || SHA256(tag), which also describes the reason Because this is a 64-byte long context-specific constant and ...
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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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3 votes
2 answers
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What data is hashed to produce the block hash?

Exactly which items from a block are included in the data that is hashed to produce the block hash?
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1 vote
1 answer
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How a real mining code treats difficulty?

I have come up recently with "how to mine bitcoin using python" or "how to mine bitcoin using golang" and as I have been observing all these source code, not only I'm confused but ...
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Estimate total number of hashes Chapter 10 "Mastering Bitcoin" [duplicate]

In Chapter 10 of "Mastering Bitcoin", the Author writes "With this level of difficulty, a single miner processing 1 trillion hashes per second (1 terahash per second or 1 TH/sec) would ...
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2 answers
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Merkle tree hash - Computing hash manually doesnt match the one computed by SHA256D64

I am trying to go through the code to check the merkle tree hash computation done by BlockMerkleRoot in bitcoin core. The hash computed using online tools by appending transaction hashes is different ...
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2 votes
2 answers
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How can we derive all work ever done on the system from the lowest hash ever found?

If not mathematically (I imagine the proof might be quite rigorous), could you please provide an intuitive explanation for why the lowest hash ever found tells approximates the total amount of work ...
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