A hash is a mathematically reproducible but irreversible process which takes one value as an input and predictably produces a derived value as an output. Hashing is central to Bitcoin mining as well as the generation of Bitcoin addresses.
0
votes
1answer
42 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 ...
1
vote
0answers
91 views
attempting to decipher a cgminer share.log
Here is 1 entry from a share processed in a feathercoin mine pool:
...
3
votes
1answer
330 views
Are Bitcoin ASICs good for anything else other than mining? [duplicate]
If I purchase an ASIC (hypothetically) and then for whatever reason Bitcoin disappears, becomes defunct or otherwise, is there anything else I could possibly use it for, such as SHA256 cracking - or ...
0
votes
1answer
147 views
Hashrates for Opteron and Xeon CPUs
I'm looking for the benchmarked hashrates of both a 1.0GHz Opteron 2007 CPU, as well as a 1.2GHz Xeon 2007 CPU. I looked here but didn't see them mentioned.
Also, on that references page, I don't see ...
4
votes
2answers
142 views
How do pool operators do their hashing?
For every "getwork" served by the pool, a Merkle root must be calculated for a block. The run time of SHA-256 is proportional to the number of "chunks" of 256 bits, and a typical block will have ...
3
votes
1answer
143 views
Explainations about chaining of transactions
I'm reading through Satoshi's paper, and in Section 2. Transactions, he starts by saying:
We define an electronic coin as a chain of digital signatures. Each owner transfers the coin to the next by ...
2
votes
1answer
194 views
Hashrate falls by factor of 1000x when now block is found?
Very often my mining hashrate falls from the usual ~550 Mhash/s to about 400-500 khash/s, and I have noticed direct correlation in time with messages like these:
btcguild.com:8332 25/04/2013 ...
-1
votes
3answers
74 views
Why can't just any hash be used for a block? [duplicate]
disclaimer: I'm completely new at this, basic computer skills limited to GUI point-&-click
I took a look at how difficulty was explained, that it is "increased" by requiring the SHA-256 ...
3
votes
0answers
19 views
Could the target become unreachable? [duplicate]
As far as I understand it, the target T is a floating point number that is adjusted based on the moving average of the difficulty of some previous transactions. Mining a block happens when somebody is ...
5
votes
2answers
104 views
Is it possible for the network to stop finding valid blocks?
The hashing problem is by design computationally hard, because SHA-256 hashes are for all intents and purposes random strings with no direct link to their inputs, and there's no (known) way to ...
3
votes
1answer
69 views
A full/multi nonce range search or just a partial range search?
In a work, there are only two elements in the block header change between hash attempts. That is, NTime and Nonce. The miner starts the nonce search to get a valid share, and there are several ...
2
votes
2answers
215 views
What determines SHA256 performance on different types of hardware?
I know the answers to many questions on here briefly touch on this point, but I'd like to get a consolidated answer that really touches on the key differences between different types of hardware which ...
1
vote
1answer
45 views
given a json of a block, how do I calculate its hash?
Here is the genesis block with its hash. How the hash was calculated?
{
"hash":"000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f",
"ver":1,
...
8
votes
2answers
327 views
Can the BitCoin network be used for cracking?
I'm assuming that the BitCoin economy is rapidly building a computing cluster capable of unprecedented amount of hash searching.
Would it be possible for an attacker to leverage this to crack other ...
2
votes
2answers
145 views
Why does Bitcoin use two hash functions (SHA-256 and RIPEMD-160) to create an address?
Why do we use 2 hash functions (both SHA and RIPEMD) to create an address? Why not just use one hash function?
0
votes
1answer
110 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.
...
3
votes
1answer
160 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 ...
2
votes
2answers
310 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 ...
3
votes
3answers
292 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 ...
3
votes
1answer
146 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 ...
3
votes
1answer
307 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.
{
...
5
votes
4answers
225 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 ...
4
votes
2answers
397 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)
...
6
votes
3answers
4k 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 ...
7
votes
4answers
6k views
When is GPU mining considered not-profitable?
As GPU mining made CPU mining non-profitable, at some point in time more specialized mining hardwares (FPGA and ASIC) would make GPU mining non-profitable.
When is GPU mining considered ...
2
votes
2answers
118 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?
3
votes
1answer
901 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:
...
-2
votes
1answer
318 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 ...
2
votes
1answer
322 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?
...
5
votes
1answer
310 views
Why does Bitcoin use two rounds of SHA256?
Each blocked is hashed twice. Why isn't one application of SHA256 enough?
5
votes
1answer
422 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 ...
5
votes
1answer
308 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
166 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 ...
2
votes
1answer
250 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 ...
5
votes
3answers
1k 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?
10
votes
5answers
3k 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 ...
6
votes
2answers
320 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 ...
3
votes
1answer
287 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:
...
6
votes
1answer
786 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 ...
0
votes
1answer
494 views
Mining software and pool tricks
Just changing the nonce of a block to be mined is not enough to cover enough hashes to solve it. What are the most common tricks used by the mining software and pools in order to create enough getwork ...
6
votes
4answers
2k views
Why would someone rent hashing power?
I have seen some people on the bitcointalk forum looking for hashing power to rent (here is one example) and usually they pay more to rent the rig than they would earn by selling the mined coins at ...
3
votes
2answers
652 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?
4
votes
2answers
1k views
What hashing speed does my hardware have?
I'm checking this page to know what hashing speed my hardware has. But there's no explanation about the acronyms.
For my Core 2 Quad Q9650, what's the expected hashing speed?
14
votes
2answers
742 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 ...
7
votes
2answers
2k 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 ...
8
votes
2answers
646 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?
11
votes
2answers
370 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
...
1
vote
1answer
116 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.
8
votes
2answers
1k 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 ...
9
votes
2answers
1k 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.
