Linked Questions

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2answers
448 views

Required number of bits in nonce [duplicate]

Is there a formal proof that with N bits to iterate in the nonce of the block, a hash satisfying proof of work will be ever found? How large that N (number of bits in the nonce) should be to satisfy ...
1
vote
1answer
126 views

What if next block cannot be mined? [duplicate]

AFAIK to create the next block, there must be a specific structure (specific number of leading zeros) in the has output calculated on the block's header. This header contains a set of fixed parts (...
18
votes
1answer
7k views

What is the expected time until the next block is found?

https://bitcoin.stackexchange.com/a/3908/659 says: Luckily, you'll only have to wait five minutes on average for a block to be found (blocks are one every ten minutes, so the expected delay until ...
9
votes
2answers
3k views

What is the longest time gap between blocks in 2010 - 2011?

I notice on blockexplorer that block 159531 was mined at 2011-12-28 10:53:53 and the next block was mined at 2011-12-28 11:24:58 - a gap of more than half an hour. I know the 10-minutes-per-block rule ...
7
votes
2answers
2k views

How is it that concurrent miners do not subvert each other's work?

Every time a new block is added on top of block chain, the miners have to restart their work because the next block has to have a proper reference to previous block. Let's suppose that there is some ...
12
votes
2answers
723 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 ...
4
votes
2answers
1k views

Why does an adversary have to control 50% of the computing power to double spend?

If transactions in a block are valid, in order to add that block in the block chain, a proof of work needs to be found. I have read the bitcoin paper by Satoshi. If the difficulty of the proof of ...
3
votes
2answers
2k views

how long does it take to get 6 confirmations with confidence of 99%

I had this question in an exam but I was not very sure how to solve it: Suppose Bob the merchant wants to have a policy that orders will ship within x minutes after receipt of payment. What value of ...
2
votes
1answer
461 views

Has the nonce used in mining been sized?

In the mining process, everytime a block has to be confirmed, a certain hash with an incremental nonce is generated: If the nonce is a 32 bit number it can assume a value between 0 and 2^32 - 1. It ...
5
votes
1answer
474 views

How does mining process takes Approximately 10 minutes?

I don't think that I fully understood the "difficulty" topic in blockchain, and therefore I don't understand how mining process takes close to 10 minutes. If I have "Target" value (some hash value, ...
1
vote
1answer
257 views

The probability that the entire network generates at least two blocks within 10 minutes?

We know that Bitcoin network on average generates one block per 10 minutes. Is there a formula to compute the probability that the entire network generates at least two blocks within 10 minutes by ...
0
votes
3answers
490 views

More than one valid hash block

Discovering a new block is a task about generation of millions of hashes in order to find one valid hash, which is a hash less than the current target. The question is: Are there more than 1 valid ...
0
votes
1answer
373 views

The probability of block generation by two miners in a special case?

If network would include 2 mining pools (pool_1 and pool_2) with the hashpower of 49% and 51%,respectively, then wo want to calculate the probability that in 10 minutes, exactly 2 blocks would be ...
1
vote
1answer
184 views

Does 4 byte Nonce enough to proof of work?

Is it always possible to find an hash value of a block, smaller than the current difficulty, just using 4 byte (Nonce) ? How can we be sure about it ?
1
vote
1answer
159 views

Zero-BTC transaction fees, service-specific mining pools and external compensation

Bitcoin is a network that is proven to be stable, but if you want applications on top of Blockchains you have to play by the rules of the system. For notary use cases (for example), where you would ...