Some Frequently Asked Questions on Selfish Mining
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We want to find a bit partial 3-way collision on SHA The first bit will do. Bitcoin mining pool faqs things toghether mean that we want to find three bit blocks AB and C such that: However, the rise of bitcoin has led to the commercial availability of powerful mining equipment. This readily available computing power can be used to mount cryptographic attacks more easily, for instance to find larger collisions than was previously believed to be possible.
We intend to demonstrate it concretely. Reaching a bit collision would be a significant milestone. Publish it on this website. Write a paper explaining the process and submit it to a cryptology conference. To the best of our knowledge, not much.
In particular, it is quite unlikely that it could ever be used to perform any kind of cyber-criminal act. This was done using up to CPU cores at bitcoin mining pool faqs university of Lille-1, and it took days.
Finding a bit partial collision is 65' times harder, and it will require about exa-hashes in total yes, this is '''''' To the best of our knowledge, no algorithm is presently known to find any kind of collision on the full hash function faster than brute-force. The situation is not the same with legacy hash functions such as MD5 and SHA-1, where faster-than brute force collision-finders exist as such, these hash functions are considered to be broken.
Basically, our plan works in two steps: Build 3 lists AB and C each containing between 4 and 8 billions bit blocks whose hash start with at least 32 zero bits. For instance, there is bitcoin mining pool faqs algorithm invented in by Ivica Nikolic and Yu Sasaki and described in a research paper.
In theory, it would require 3. However, it would also require the storage of an absurdly high volume of data millions of terabytes. It thus seems completely impractical for our purpose. We currently believe that it cannot bitcoin mining pool faqs faster in practice than the naive ideas for relevant parameters ranges. We are investigating a technique invented by Antoine Joux and described in his book Algorithmic Cryptanalysis"that we believe could be practically faster.
Bitcoin miners are capable of carrying out the first step see above much faster than classical computers. So, the bottleneck is actually the first step: This pool implements the stratum mining protocol.
In this protocol, the miners connect to a pool server that sends them mining work to do. They also regularly send shares to prove to the pool server that they are actually mining. This pools sends custom work to the miners, and keeps the shares a valid share is one element of the three lists built in step 1 of our plan, see above.
Once we have received about 12 billions share, we are done. Nothing, besides the satisfaction of knowing that you are helping perform a large and cool computation. Normal bitcoin mining pools remunerate miners in bitcoins, based on their contribution the higher the hashrate, the higher the retribution. This pool, however, does not produces any bitcoin mining pool faqs see belowso there is no reward to share amongst miners.
You're helping us accomplish the goal stated above: We can't gain anything financially. This pool doesn't mine any valid cryptocurrency see below. A share is awarded by the mining pool to the clients bitcoin mining pool faqs present a valid proof of work of the same type as the proof of work that is used for creating blocks, but of lesser difficulty, so that it requires less time on average to generate.
In a pool, miners regularly send "shares" to the pool server. These are the description of hash blocks whose hash start by a given number of zero bits. By adjusting the pool difficulty bitcoin mining pool faqs to be mistaken with the network difficultythat of the global blockchainthe pool server controls how many zero bits valid shares hash to.
So, valid shares at any difficulty is actually what we need for the first step of our grand plan. We need roughly 12''' shares at difficulty one, or slighlty less at a higher difficulty see below. What is the difficulty bitcoin mining pool faqs this pool? There is no fixed difficulty. The pool server tries to adjust the difficulty bitcoin mining pool faqs that each miner sends shares as fast as possible.
As stated above, our goal is to get 12 billion shares as fast as possible. Miners produce shares faster at low difficulty, so indeed it bitcoin mining pool faqs be rational to set the difficulty to the minimum. One problem is that the controller of most mining rigs probably a low-cost ARM device such as a Raspberry Pi or a BeagleBoard is not capable of reporting shares very frequently in normal bitcoin mining, reporting shares bitcoin mining pool faqs infrequent, so it doesn't matter.
Basically, the process works in two steps. Then, it will find the optimal difficulty by sending you jobs of increasing difficulty and measuring the rate at which shares are produced. Answering this requires dwelving into the details of the stratum mining protocol. The pool server has a lot of control over the work the miners actually do. In principle, it sends bitcoin mining pool faqs miner parts of a transaction header block.
The miner has to re-assemble the parts in a way that make the header a valid share. For this, the miner may choose the bit noncebut it can also change bitcoin mining pool faqs of the coinbase transaction. Bytes of the block are chosen by the pool server 4-byte block version and byte hash of the previous block.
Bytes are the merkle hash root impredictably depends on the coinbase transaction partially chosen by the miner. Bytes are chosen by the pool server network time and encoded network difficulty. Bytes are determined by the miner bit nonce. If these 80 bytes hash to something that begins with enough zero bit, then it is a valid share and will be sent back to the pool server. In order to produce an actual bitcoin transaction block, these values have to be chosen according to the bitcoin specification and current state of the blockchain.
In this pool, however, the portions of the block that bitcoin mining pool faqs under the control of the pool server are chosen somewhat arbitrarily. Even if your miner cannot bring you a profit by mining bitcoin if it is too slow or not energy-efficient enoughit can still be useful to us! With such mining rigs, our share collection will be over in 4 months.
The pool server will send you jobs of a higher difficulty, and you'll produce higher-quality shares. To make it very clear that we are not mining bitcoins, we only send to the miners blocks that cannot in any way encode valid bitcoin transactions. In addition, instead of including a valid network time, we include the number 0xdeadbeef.
No bitcoin node will ever accept these blocks and they will never be included bitcoin mining pool faqs the blockchain.
As such, they can't be used to acquire bitcoin mining pool faqs. In addition, the low pool difficulty makes it extremely unlikely that the shares sent by the miners to the pool server meet the current difficulty level of the global bitcoin network. Lastly, and even though it is not as convincing as the technical arguments above, we are academics and this whole project has been approved by our institutions. In a Ponzi scheme, we'd ask you to invest and promise a tremendous bitcoin mining pool faqs on investment.
Here, we will give you nothing. No false promises, no Ponzi scheme. All our code for this project is in a public github repository.