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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5
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1answer
1k 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: '...
42
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1answer
12k 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
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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?
37
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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
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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
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3answers
3k 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
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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
788 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.
23
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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
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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.
100
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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 ...
17
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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. ...

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