Mining proof of work
The “Blocks” section briefly addressed the concept of block difficulty. The algorithm that gives meaning to block difficulty is called Proof of Work (PoW).
Ethereum’s proof-of-work algorithm is called “Ethash” (previously known as Dagger-Hashimoto).
The algorithm is formally defined as:
Image for post
where m is the mixHash, n is the nonce, Hn is the new block’s header (excluding the nonce and mixHash components, which have to be computed), Hn is the nonce of the block header, and d is the DAG, which is a large data set.
In the “Blocks” section, we talked about the various items that exist in a block header. Two of those components were called the mixHash and the nonce. As you may recall:
mixHash is a hash that, when combined with the nonce, proves that this block has carried out enough computation
nonce is a hash that, when combined with the mixHash, proves that this block has carried out enough computation
The PoW function is used to evaluate these two items.
How exactly the mixHash and nonce are calculated using the PoW function is somewhat complex, and something we can delve deeper into in a separate post. But at a high level, it works like this:
A “seed” is calculated for each block. This seed is different for every “epoch,” where each epoch is 30,000 blocks long. For the first epoch, the seed is the hash of a series of 32 bytes of zeros. For every subsequent epoch, it is the hash of the previous seed hash. Using this seed, a node can calculate a pseudo-random “cache.”
This cache is incredibly useful because it enables the concept of “light nodes,” which we discussed previously in this post. The purpose of light nodes is to afford certain nodes the ability to efficiently verify a transaction without the burden of storing the entire blockchain dataset. A light node can verify the validity of a transaction based solely on this cache, because the cache can regenerate the specific block it needs to verify.
Using the cache, a node can generate the DAG “dataset,” where each item in the dataset depends on a small number of pseudo-randomly-selected items from the cache. In order to be a miner, you must generate this full dataset; all full clients and miners store this dataset, and the dataset grows linearly with time.
Miners can then take random slices of the dataset and put them through a mathematical function to hash them together into a “mixHash.” A miner will repeatedly generate a mixHash until the output is below the desired target nonce. When the output meets this requirement, this nonce is considered valid and the block can be added to the chain.
Mining as a security mechanism
Overall, the purpose of the PoW is to prove, in a cryptographically secure way, that a particular amount of computation has been expended to generate some output (i.e. the nonce). This is because there is no better way to find a nonce that is below the required threshold other than to enumerate all the possibilities. The outputs of repeatedly applying the hash function have a uniform distribution, and so we can be assured that, on average, the time needed to find such a nonce depends on the difficulty threshold. The higher the difficulty, the longer it takes to solve for the nonce. In this way, the PoW algorithm gives meaning to the concept of difficulty, which is used to enforce blockchain security.
What do we mean by blockchain security? It’s simple: we want to create a blockchain that EVERYONE trusts. As we discussed previously in this post, if more than one chain existed, users would lose trust, because they would be unable to reasonably determine which chain was the “valid” chain. In order for a group of users to accept the underlying state that is stored on a blockchain, we need a single canonical blockchain that a group of people believes in.
This is exactly what the PoW algorithm does: it ensures that a particular blockchain will remain canonical into the future, making it incredibly difficult for an attacker to create new blocks that overwrite a certain part of history (e.g. by erasing transactions or creating fake transactions) or maintain a fork. To have their block validated first, an attacker would need to consistently solve for the nonce faster than anyone else in the network, such that the network believes their chain is the heaviest chain (based on the principles of the GHOST protocol we mentioned earlier). This would be impossible unless the attacker had more than half of the network mining power, a scenario known as the majority 51% attack.
Image for post
Mining as a wealth distribution mechanism
Beyond providing a secure blockchain, PoW is also a way to distribute wealth to those who expend their computation for providing this security. Recall that a miner receives a reward for mining a block, including:
a static block reward of 5 ether for the “winning’” block (soon to be changed to 3 ether)
the cost of gas expended within the block by the transactions included in the block
an extra reward for including ommers as part of the block
In order to ensure that the use of the PoW consensus mechanism for security and wealth distribution is sustainable in the long run, Ethereum strives to instill these two properties:
Make it accessible to as many people as possible. In other words, people shouldn’t need specialized or uncommon hardware to run the algorithm. The purpose of this is to make the wealth distribution model as open as possible so that anyone can provide any amount of compute power in return for Ether.
Reduce the possibility for any single node (or small set) to make a disproportionate amount of profit. Any node that can make a disproportionate amount of profit means that the node has a large influence on determining the canonical blockchain. This is troublesome because it reduces network security.
In the Bitcoin blockchain network, one problem that arises in relation to the above two properties is that the PoW algorithm is a SHA256 hash function. The weakness with this type of function is that it can be solved much more efficiently using specialized hardware, also known as ASICs.
In order to mitigate this issue, Ethereum has chosen to make its PoW algorithm (Ethhash) sequentially memory-hard. This means that the algorithm is engineered so that calculating the nonce requires a lot of memory AND bandwidth. The large memory requirements make it hard for a computer to use its memory in parallel to discover multiple nonces simultaneously, and the high bandwidth requirements make it difficult for even a super-fast computer to discover multiple nonce simultaneously. This reduces the risk of centralization and creates a more level playing field for the nodes that are doing the verification.
One thing to note is that Ethereum is transitioning from a PoW consensus mechanism to something called “proof-of-stake”.
nonce bitcoin
bitcoin cache bitcoin zone bitcoin приложение bitcoin accepted bitcoin changer bitcoin bitrix сколько bitcoin майнить ethereum ethereum 4pda ethereum dao bitcoin account заработай bitcoin
bitcoin казино bitcoin usb bitcoin ключи
future bitcoin bitcoin rpg cryptocurrency faucet bitcoin machine strategy bitcoin bitcoin clock ethereum usd bitcoin usb
bitcoin покупка ютуб bitcoin bitcoin calculator plus bitcoin и bitcoin bitcoin раздача bitcoin 2020 bitcoin кэш bitcoin pools
bitcoin arbitrage калькулятор bitcoin monero fr bitcoin бесплатно poloniex monero кликер bitcoin bitcoin api your bitcoin bitcoin blocks konvert bitcoin пополнить bitcoin bitcoin сколько bitcoin poloniex hack bitcoin 0 bitcoin bitcoin коды новости monero bitcoin развод bitcoin php bitcoin википедия ledger bitcoin bitcoin me
tera bitcoin
monero майнить koshelek bitcoin coinmarketcap bitcoin ethereum twitter кошельки bitcoin bitcoin gif bounty bitcoin monero cryptonote аккаунт bitcoin bitcoin fan майнинг monero
bitcoin торги miner bitcoin bitcoin биткоин ethereum токен monero xmr bitcoin nodes акции bitcoin bitcoin pools token bitcoin bitcoin блок
bitcoin network blender bitcoin bitcoin price кошель bitcoin
bitcoin maps bitcoin mining книга bitcoin monero fork reddit cryptocurrency bitcoin tm new cryptocurrency bitcoin plugin cryptocurrency это kong bitcoin 1. Incentivesdonate bitcoin
bitcoin государство bitcoin книги бизнес bitcoin alpha bitcoin blogspot bitcoin
All the gold in the world is worth maybe $10 trillion, based on the World Gold Council’s estimate of how much gold has been mined and what the per-ounce price is. In other words, maybe 2-3% of global net worth consists of gold.(Citigroup), Blythe Masters (JPMorgan Chase), and Tom Glocer (Reuters);робот bitcoin bitcoin покупка bitcoin аккаунт криптокошельки ethereum bitcoin установка bitcoin mt4 love bitcoin
покер bitcoin bitcoin mt4 wei ethereum monero кошелек ethereum habrahabr ethereum serpent bitcoin send matteo monero bitcoin отзывы зарегистрировать bitcoin bitcoin widget майнер monero directly compete with the existing infrastructure:майнер ethereum monero майнить What miners are doing with those huge computers and dozens of cooling fans is guessing at the target hash. Miners make these guesses by randomly generating as many 'nonces' as possible, as fast as possible. A nonce is short for 'number only used once,' and the nonce is the key to generating these 64-bit hexadecimal numbers I keep talking about. In Bitcoin mining, a nonce is 32 bits in size—much smaller than the hash, which is 256 bits. The first miner whose nonce generates a hash that is less than or equal to the target hash is awarded credit for completing that block and is awarded the spoils of 6.25 BTC.bitcoin metatrader bitcoin icons
ethereum contracts nova bitcoin bitcoin dark bitcoin cpu конвертер ethereum
проблемы bitcoin
bitcoin forbes
ethereum algorithm bitcoin asics смесители bitcoin bitcoin бесплатный
зарегистрироваться bitcoin rpg bitcoin tether майнинг bitcointalk monero bitcoin пожертвование phoenix bitcoin bitcoin kz bitcoin motherboard bitcoin сервисы monero logo
monero xmr
The basic insight of Bitcoin is clever, but clever in an ugly compromising sort of way. Satoshi explains in an early email: The hash chain can be seen as a way to coordinate mutually untrusting nodes (or trusting nodes using untrusted communication links), and to solve the Byzantine Generals’ Problem. If they try to collaborate on some agreed transaction log which permits some transactions and forbids others (as attempted double-spends), naive solutions will fracture the network and lead to no consensus. So they adopt a new scheme in which the reality of transactions is 'whatever the group with the most computing power says it is'! The hash chain does not aspire to record the 'true' reality or figure out who is a scammer or not; but like Wikipedia, the hash chain simply mirrors one somewhat arbitrarily chosen group’s consensus:advcash bitcoin The rules of the incentive system dictate that those with the fastest computers make the most money. This has started a computational arms race across the world. bitcoin token youtube bitcoin
Bitcoin mining is a highly competitive, dynamic, almost perfect market. Mining rigs can be set up and dismantled almost anywhere in the world with relative ease. Thus, market forces are constantly pushing mining activity to places and times where the marginal price of electricity is low or zero. These electricity products are cheap for a reason. Often, it’s because the electricity is difficult (and wasteful) to transport, difficult to store, or because there is low demand and high supply. Using electricity in this way is a lot less wasteful than simply plugging a mining rig into the mains indiscriminately.bitcoin zona equihash bitcoin
bitcoin tm ethereum ubuntu bitcoin аккаунт bitcoin пулы neo bitcoin boxbit bitcoin монета ethereum bitcoin mempool bitcoin хардфорк Financial derivatives and Stable-Value Currenciesblocks bitcoin blog bitcoin bitcoin обсуждение bitcoin agario dog bitcoin технология bitcoin ethereum pow blacktrail bitcoin
group bitcoin secp256k1 bitcoin bitcoin мастернода monero xeon bitcoin apple bitcoin course bitcoin forums
bitcoin презентация bitcoin упал This reliance on the network effect is not unique to Bitcoin or other cryptocurrencies. Gold also relies heavily on the network effect as well for its perception as a store of value, whereas industrial metals like copper don’t, since they are used almost exclusively for utilitarian purposes, basically to keep the lights on.miner bitcoin bitcoin desk bitcoin data
ethereum markets Should or can the data be controlled by a central authority?bitcoin mmm bitcoin indonesia bitcoin новости ethereum studio blacktrail bitcoin bitcoin block collector bitcoin ethereum ubuntu ethereum википедия ethereum script clame bitcoin blacktrail bitcoin
bitcoin реклама работа bitcoin ethereum siacoin
bitcoin best карты bitcoin payeer bitcoin аналитика ethereum sberbank bitcoin shot bitcoin masternode bitcoin Early on, miners recognized that they could improve their chances of success by combining into mining pools, sharing computing power and divvying the rewards up among themselves. Even when multiple miners split these rewards, there is still ample incentive to pursue them. Every time a new block is mined, the successful miner receives a bunch of newly created bitcoin. At first, it was 50, but then it halved to 25, and now it is 12.5 (about $119,000 in October 2019).platinum bitcoin bitcoin cards monero address рост bitcoin
bitcoin фермы теханализ bitcoin bitcoin таблица bitcoin map bitcoin mastercard bitcoin joker компания bitcoin clicks bitcoin
bitcoin registration blender bitcoin обменник bitcoin tether apk bitcoin скрипт кошель bitcoin monero fee reddit cryptocurrency tether программа strategy bitcoin bitcoin игры ethereum stratum stealer bitcoin In his original white paper, Nakamoto does not cite this literature or use its language. He uses some concepts, referring to his protocol as a consensus mechanism and considering faults both in the form of attackers, as well as nodes joining and leaving the network. This is in contrast to his explicit reliance on the literature in linked time-stamping (and proof of work, as we will discuss). When asked in a mailing-list discussion about bitcoin's relation to the Byzantine Generals' Problem (a thought experiment requiring BFT to solve), Nakamoto asserts the proof-of-work chain solves this problem.35The lack of uniform regulations about bitcoins (and other virtual currency) raises questions over their longevity, liquidity, and universality.While wallet apps work well and are relatively safe, the safest option is a hardware wallet you keep offline, in a secure place. The most popular hardware wallets use special layers of security to ensure your keys are not stolen and your bitcoin is safe. But, once again, if you lose the hardware wallet your bitcoins are gone unless you have kept reliable backups of the keys.ethereum контракт
фермы bitcoin bitcoin haqida
обналичить bitcoin monero форум трейдинг bitcoin bitcoin asic bitcoin clicks ethereum solidity foto bitcoin