We’re rewarding the question askers & reputations are being recalculated! Read more.

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.

Filter by
Sorted by
Tagged with
0
votes
1answer
281 views

How many shares will be found for a given hashrate?

Many pools offer a difficulty of 1 per share. Since variable difficulty is a feature of a couple of pools, I'd like to understand how many shares would be created at varying levels of difficulty. ...
5
votes
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 ...
7
votes
2answers
572 views

Possible to create a double spend attack by replacing a Tx in the merkle tree?

This question on crypto.SE describes how preimage attacks are avoided in the Bitcoin network. For a second preimage attack: hash(x) = hash(y) implies hash(hash(x)) = hash(hash(y)) So it ...
11
votes
4answers
6k views

Where is Double hashing performed in Bitcoin?

where in the Bitcoin Protocol is SHA256(SHA256(x)) performed and why?
138
votes
4answers
228k views

What are bitcoin miners really solving?

As with mining, what are the bitcoin miners really solving? I read they are solving hashes, but what does that really mean. Can we see what they are solving? Can someone give an example of what a ...
3
votes
2answers
4k views

Given the probability of finding a block, and time taken, can I infer hashrate?

I'm trying to externally calculate the hashrate of a given miner based only on an arbitrarily defined target that I assign, then calculate probability it will be found. Once this probability is ...
4
votes
3answers
642 views

Future-proofing a deflationary currency from future counterfeiting

Say someone locks away a wallet in durable storage for 100 years and BitCoins are still actively used. Are those BitCoins still going to be valid if they haven't been traded in/upgraded to the newer ...
32
votes
4answers
5k views

Why are hashes in the bitcoin protocol typically computed twice (double computed)?

According to the wiki specification of the bitcoin protocol, hashes are typically "computed twice". For example: hello 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824 (first round of ...
4
votes
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. { "...
4
votes
2answers
480 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?
7
votes
4answers
501 views

How is it possible that transactions can be added to a block currently being mined?

It seems counter-intuitive that the current block can be hashed and transactions can be added to it, however that is what this thread indicates. Can someone help me connect the dots (not necessarily ...
17
votes
4answers
15k views

How do you perform double-SHA-256 encoding?

The Bitcoin Protocol-specification gives an example of double-SHA-256 encoding. hello 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824 (first round of sha-256) ...
12
votes
3answers
14k views

Why are Bitcoin calculation “useless”?

The FAQ says: Why don't we use calculations that are also useful for some other purpose? To provide security for the Bitcoin network, the calculations involved need to have some very ...
2
votes
2answers
268 views

What makes difficulty more difficult?

Miners attempt to hash block data such that it is below a certain target value? By Cantor's diagonal proof aren't there infinitely many successful values below any given target?
18
votes
1answer
14k views

Relationship between Hash-Rate and Difficulty

What is the algebraic relationship between Total Network Hash-Rate and Difficulty?
7
votes
1answer
3k views

How does a miner perform hashing?

I'm trying to walk my way through the process by which a miner hashes. Let's say the getwork request returns a data field of: ...
-1
votes
1answer
854 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. ...
4
votes
3answers
1k 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? ...
9
votes
1answer
1k views

Why does Bitcoin use two rounds of SHA256?

Each blocked is hashed twice. Why isn't one application of SHA256 enough?
11
votes
5answers
3k views

how can I insert an arbitrary sha256 hash into the blockchain?

If I want to prove that I wrote a particular document before a certain point in time, it would be sufficient to generate the sha256 hash of the document and somehow arrange for that hash to appear in ...
9
votes
8answers
3k views

Can more than 1 block be solved per 10 mins on average (LONG TERM)?

I am wondering whether it is possible for a supercomputer to find the next 1000 blocks in a very short amount of time. Hypothetically, if a government agency concentrated a supercomputer on hashing, ...
5
votes
3answers
7k views

Where can I see an input that will hash to a solution?

So as my understanding goes, there's some input (block header) that needs to be altered (via a nonce or other mechanism) which is run through a SHA256 to generate an output with X amount of leading 0'...
7
votes
1answer
3k views

Can an SHA256 hash be used as an ECDSA private key?

Is it possible to map a pass-phrase directly to a Bitcoin private key by using its SHA256 hash? I remember reading somewhere that not all 256 bit values are valid ECDSA private keys. If so, how can I ...
27
votes
1answer
5k views

Why are Bitcoin addresses hashes of public keys?

Currently, Bitcoin addresses and their checksums are constructed from the public key by a using repeated hashing with SHA256 and RIPEMD160. Now I understand the reasoning behind using hashing for ...
3
votes
1answer
477 views

Is there a guaranteed hash for every block? [duplicate]

Possible Duplicate: Nonce size - Will it always be big enough? My question may be misphrased, if so, I'll correct it if you let me know in the comments. My understanding of mining is that the ...
3
votes
1answer
681 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 ...
9
votes
3answers
7k views

Relation between Network Hash-Rate & bitcoin value?

how is the relation betweeen network hash rate to healthyness of bitcoin, such as bitcoin value compared to USD, or the growth rate of this currency?
27
votes
8answers
16k views

How can I generate a vanity Bitcoin address?

I once found a program that was capable of creating Bitcoin addresses with specific words in them, but can't find it now. Is there a trusted program, in the Ubuntu repositories for example, that can ...
12
votes
2answers
2k views

Two blocks, two transactions, same hash

Would a block containing a transaction with an identical hash as a previous transaction be considered valid? That is, if someone made a transaction for generating Bitcoins and solve two blocks with ...
5
votes
1answer
986 views

In Getwork, how does one calculate the value of Hash1?

(I know the hash1 and midstate are eventually going to be deprecated, but I'm a little curious about them) In Getwork there is a field hash1. From a sample call to bitcoind I received its value as: '...
41
votes
1answer
11k views

How are transaction hashes calculated?

I'm trying to calculate the hash of transactions in bitcoin blocks, but I'm not getting the right answers. For example, the genesis block has a single transaction. Here's how I'm attempting to ...
8
votes
3answers
8k views

How to calculate a hash of a Tx?

How does one calculate the hash of a Tx? Which fields need to be double SHA hashed and in what order?
36
votes
2answers
9k views

Nonce size - Will it always be big enough?

If I understand correctly, the block only has 4 bytes (32 bits) for the nonce. Is it possible for the difficulty to become high enough that there are no nonce solutions? If so, then what options does ...
10
votes
2answers
5k views

How can I measure the total hashing power of the Bitcoin network?

Is there a way to measure what is the total hashing power of the Bitcoin network at a given time? For pooled mining it isn't a problem - one can rely on statistics provided by the pool (assuming one ...
12
votes
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?
14
votes
2answers
2k views

How many Integer Operations on a GPU are necessary for one Hash?

I thought it was the ALU OPs like here: https://bitcointalk.org/index.php?topic=7964.0 ArtForz speaks of much higher values, though: https://bitcointalk.org/index.php?topic=4689.msg68933#msg68933 ...
2
votes
1answer
768 views

How do the clients agree on the target to hash for? [closed]

Edit: They do not agree on a specific target hash. Any hash lower than or equal to the difficulty is sufficient. This means clients only have to agree on difficulty.
22
votes
3answers
12k views

How do I implement a Merkle Tree?

I`m slowly implementing some Bitcoin protocols, and I'm not sure how to properly understand the Merkle Tree from the Bitcoin wiki: https://en.bitcoin.it/wiki/Protocol_specification#Merkle_Trees I have ...
11
votes
2answers
6k views

Exactly how does one calculate how many BTC they will get a certain hashrate?

I am curious on how many estimated BTC I will earn at any hash rate since, I don't really think I'm really earning any BTC at 600 Mhash/s.
97
votes
12answers
9k views

Is there a way to set up proof-of-work systems so they would be even more useful?

One of the arguments made against Bitcoin's design choices is that it wastes resources authenticating transactions. In particular, finding small hashes is completely useless for the world. Are there ...
16
votes
5answers
2k views

Is Bitcoin future-proof?

As I understand things, the security and integrity of Bitcoin rely on the assumption that its hashing is "hard" in some sense. However, in the past, processing power has increased exponentially. ...