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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9
votes
1answer
588 views

When a transaction is broadcast to the network, what is actually being sent?

When a transaction is broadcasted to the network, what is being sent? Is it a hash? if yes, is it going to be the hash of: previous transaction + public key of the receiver?
6
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3answers
10k 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 ...
5
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1answer
2k views

Why do transaction/blockchain based gambling sites use such complicated methods for proving fairness?

Doesn't the block hash or the transaction id provide enough entropy (for example, by using block_hash % 37 to generate a random number between 0 and 36)? Block Chain Roulette determines the lucky ...
4
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1answer
3k views

bitcoind getmininginfo says hashespersec is 0

I started mining yesterday on a low-end system, trying to figure out how it works. I used the bincoind build from Debian. When I try bitcoind getmininginfo today, I get the following output. { "...
3
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1answer
701 views

How does the rate of getwork requests correlate with the hashrate of a miner?

In a setup where a standard bitcoind serves full difficulty targets to some mining nodes, how can I calculate the hashrate of a mining node from looking at the rate of getwork requests? Does this ...
3
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4answers
7k views

If SHA256 produces an alphanumeric hash, how can a hash be “less than a certain value”?

I was under the impression that Bitcoin's method for validating a hash involved making sure the hash started with a pre-determined number of zeroes. However, after reading the docs here, I see the ...
3
votes
2answers
10k views

Shares accepted vs hash rates?

I recently started mining LTCs, and because Im using a Nvidia card (GTX 650Ti) I have been trying out different settings in order to maximize efficiency with the hash rates. I have noticed though ...
2
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0answers
3k views

BFGminer can't find my NanoFury on Raspberry Pi

Related: BFGminer can't find my NanoFury! Posted on the RPi Exchange as well https://raspberrypi.stackexchange.com/questions/14753/bfgminer-cant-find-my-nanofury-on-raspberry-pi Forums: https:...
4
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2answers
176 views

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 ...
4
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3answers
2k views

What other purposes can I use my [obsolete] hashing hardware for?

It's pretty easy to reuse CPUs or Video cards that were previously used for Bitcoin hashing, but what can I do with FPGA hardware when the difficulty becomes too high for it to be worthwhile to mine? ...
3
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3answers
758 views

Why you need to rehash each block after a changed block when changing data in a blockchain?

Maybe my question is stupid, but, why you need to rehash each block after a changed block when changing data in a blockchain? Each block contains a hash of its data and hash of previous block. If I ...
2
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4answers
2k views

What exactly is the input for the Hash pointer in block k+1?

I'm not sure how to ask this question clearly so I will ask it three different ways and hopefully someone understands me. Is the input for the hash pointer in block k+1 just the transactions in block ...
2
votes
3answers
714 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 ...
2
votes
2answers
223 views

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)
2
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1answer
496 views

How is hash rate of mining hardware calculated

The mining hardware does a double sha-256 hash of the header while mining. Is each sha-256 operation counted when determining the hash rate or is the whole sha256(sha256(header)) counted as one hash? ...
1
vote
1answer
344 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 ...
1
vote
1answer
1k views

nBit to leading zeros in Block Hash

I am trying to understand how can I check if my Block Hash satisfies or not the nBits. For example, for block 506679 (https://blockchain.info/block-index/506679): nBits: 404454260 Block Hash: ...
1
vote
1answer
415 views

Why are blocks hashed?

Am I correct that addresses are hashed to compress a huge text-represented coprime into something of manageable size? Am I also correct that transactions are hashed for the same reason and also ...
1
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0answers
266 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. ...
1
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3answers
3k views

two people with same PUBLIC address, how will people/network know how to deliver bitcoin

I understand that a bitcoin address is a combination or more than one kind of encryption and entropy, and I also understand how improbable it is that the same address will get generated at the same ...
0
votes
1answer
695 views

Using blockchain to publish downloadable software verification codes

What is the point of comparing sha256 of downloaded file with published on the same website code? Why can't developers of currencies publish file version and sha256 hash on blockchain as alias or ...
0
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2answers
536 views

Is there any chance to check the name by bitcoin hash?

Someone recently wants to sell me an iPhone, but the seller does not want to show me anything about it. It's a second-hand phone, and I'm worried about it a little bit. Is there any chance to see the ...
0
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1answer
3k views

Solving a block and verification of transactions [duplicate]

My understanding of mining is that the reason an award of Bitcoin comes along with the solving of the current block is to give people incentive to actually try to solve the block. My understanding is ...
0
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5answers
8k views

BFGminer can't find my NanoFury!

I recently purchased a Nanofury ASIC unit. I tried running it on my Linux system, as I just let the computer sit and run. I couldn't get it to work on Linux, so I decided to give it a try on Windows = ...
0
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3answers
410 views

How Bitcoin handles addresses collisions?

Since the addresses are hashes of a public portion of a public/private ECDSA keypair, what would happen to two different people with different keys that hashes into the same address? How would ...
0
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1answer
323 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 ...
0
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1answer
144 views

How would one go about acquiring the HashofThingtoSign from this old transaction?

How would one go about acquiring the HashofThingToSign that is used in the "Signature Generation" equation for this example transaction such that it could easily also be applied to any other ...
0
votes
1answer
184 views

Extract output address from raw script in bitcoin protocol

I'm working on bitcoin protocol and exactly i want to extract raw script from output script to gain address from tx messages. for common scripts, like scripts start with 0x76(means OP_DUP), we can ...
0
votes
3answers
1k views

Generating differnet addresses from same public key?

There's a gap in my understanding regarding the generation, via hashing, of bitcoin addresses. (I'm quoting from Antonoplous below for convenience, but I have consulted multiple other sources.) ...
0
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1answer
293 views

Confused About Hash In Satoshi Nakamoto Diagram

In Satoshi Nakamoto's diagram: Consider the Hash block in the first transaction block above: How is that Hash value calculated? I see arrows from an Owner's Public Key and another arrow, so it's ...
-1
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1answer
860 views

What computations does Btcoin perform during mining? [duplicate]

Possible Duplicate: What exactly is Mining? What are the exact computations dies Bitcoin is performing during the mining? I understood that it has to do something with hashes and proof-of-work. ...

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