If the split between Ethereum and Ethereum Classic wasn’t definitive before, it is now.Ethereum Classic, the project born out of rejection of Ethereum’s reversal of The DAO, hard forked today.With that, Ethereum Classic has implemented the biggest protocol change yet, and further differentiated itself from the Ethereum project.Most importantly, the hard fork — dubbed “Die Hard” — diffused the difficulty bomb, which was set to freeze the protocol later this year.Additionally, Ethereum Classic implemented replay protection, to ensure Ethereum transactions are no longer valid on the Ethereum Classic chain and vice versa.It also adjusted technical parameters to increase the cost of certain spam attacks.“This protocol upgrade demonstrated growing maturity of Ethereum Classic, as it's starting to blaze its own path not only in terms of ideology, but also technical choices,” Ethereum Classic’s project coordinator, “Arvicco” told Bitcoin Magazine.“Such as a commitment to staying on proof-of-work consensus for a prolonged period.” The original Ethereum protocol, as implemented by the Ethereum Foundation, included a so-called “difficulty bomb.” Baked into the software, Ethereum’s mining difficulty is programmed to increase exponentially over time.

This has been unnoticeable up till now, but by around April or May of this year, it is set to increase so rapidly that mining will necessarily become unprofitable.As a result, no more blocks will be found at all, and the protocol will effectively freeze, creating an “Ice Age.” The Ethereum Foundation implemented this difficulty bomb to force its own hand — and that of the broader Ethereum community.bitcoin ke paypalAs outlined in its release documents, the Ethereum Foundation planned to roll out the Ethereum project in several stages, each one requiring a hard fork.bitcoin norwegian studentThe difficulty bomb was implemented to ensure that developers and the community would have to switch to a new protocol this year; eventually working toward a proof-of-stake mining algorithm known as “Casper.” As a continuation of the original Ethereum protocol, Ethereum Classic also included that difficulty bomb.piattaforme bitcoin

The Ethereum Classic community, however, has decided it will not follow the Ethereum Foundation road map, most notably regarding Casper.As such, there is little need for Ethereum Classic to keep the difficulty bomb, and it was removed with the Die Hard hard fork.This gives the project more time to work on further protocol development, Arvicco said.“Now that the most critical technical issues such as difficulty bomb and replay protection are resolved, ETC dev team will start focusing more on longer-term changes, such as monetary policy and improved platform stability and security.” With every hard fork, there exists a risk of not everyone switching to the new protocol, in effect creating two different networks and currencies.bitcoin haendlerThis is how the Ethereum Classic project itself started, of course, and could happen again.bitcoin exchange denver

So far, however, Die Hard seems to have gone through with few holdouts.While it is too early to tell with full certainty whether the ecosystem has fully switched to the new protocol, there didn’t appear to be much opposition beforehand.A vast majority of hash power has also made the switch — though at time of writing a small number of miners hadn’t yet.“Even though we campaigned for two weeks for everyone to upgrade, about 0.5 percent of hash power kept mining on the old chain for a while,” Arvicco said.litecoin chart difficulty“That was to be expected, though; with our last fork in October that was about 3 to 5 percent.So, there is  progress.” And the odds of these holdouts bootstrapping their own currency seems unlikely, Arvicco believes.“Not unless there is a community ready to support it both in terms of participation and real money.And the prospects of such community is not good with the bomb blowing up pretty soon.”

The word mining originates in the context of the gold analogy for crypto currencies.Gold or precious metals are scarce, so are digital tokens, and the only way to increase the total volume is through mining it.This is appropriate to the extent that in Ethereum too, the only mode of issuance post launch is via the mining.Unlike these examples however, mining is also the way to secure the network by creating, verifying, publishing and propagating blocks in the blockchain.Ethereum Frontier like all blockchain technologies uses an incentive-driven model of security.Consensus is based on choosing the block with the highest total difficulty.Miners produce blocks which the others check for validity.Among other well-formedness criteria, a block is only valid if it contains proof of work (PoW) of a given difficulty.Note that in Ethereum 1.1, this is likely gonna be replaced by a proof of stake model.[The proof of work algorithm used is called Ethash (a modified version of Dagger-Hashimoto involves finding a nonce input to the algorithm so that the result is below a certain threshold depending on the difficulty.

The point in PoW algorithms is that there is no better strategy to find such a nonce than enumerating the possibilities while verification of a solution is trivial and cheap.If outputs have a uniform distribution, then we can guarantee that on average the time needed to find a nonce depends on the difficulty threshold, making it possible to control the time of finding a new block just by manipulating difficulty.The difficulty dynamically adjusts so that on average one block is produced by the entire network every 12 seconds (ie., 12 s block time).This heartbeat basically punctuates the synchronisation of system state and guarantees that maintaining a fork (to allow double spend) or rewriting history is impossible unless the attacker possesses more than half of the network mining power (so called 51% attack).Any node participating in the network can be a miner and their expected revenue from mining will be directly proportional to their (relative) mining power or hashrate, ie., number of nonces tried per second normalised by the total hashrate of the network.

Ethash PoW is memory hard, making it basically ASIC resistant.This basically means that calculating the PoW requires choosing subsets of a fixed resource dependent on the nonce and block header.This resource (a few gigabyte size data) is called a DAG.The DAG is totally different every 30000 blocks (a 100 hour window, called an epoch) and takes a while to generate.Since the DAG only depends on block height, it can be pregenerated but if its not, the client need to wait the end of this process to produce a block.Until clients actually precache dags ahead of time the network may experience a massive block delay on each epoch transition.Note that the DAG does not need to be generated for verifying the PoW essentially allowing for verification with both low CPU and small memory.As a special case, when you start up your node from scratch, mining will only start once the DAG is built for the current epoch.Note that mining 'real' Ether will start with the Frontier release.On the Olympics testnet, the Frontier pre-release, the ether mined have no value (but see Olympic rewards).

The successful PoW miner of the winning block receives: Uncles are stale blocks, ie with parent that are ancestors (max 6 blocks back) of the including block.Valid uncles are rewarded in order to neutralise the effect of network lag on the dispersion of mining rewards, thereby increasing security.Uncles included in a block formed by the successful PoW miner receive 7/8 of the static block reward = 4.375 ether A maximum of 2 uncles allowed per block.Ethash uses a DAG (directed acyclic graph) for the proof of work algorithm, this is generated for each epoch, i.e every 30000 blocks (100 hours).The DAG takes a long time to generate.If clients only generate it on demand, you may see a long wait at each epoch transition before the first block of the new epoch is found.However, the DAG only depends on block number, so it CAN and SHOULD be calculated in advance to avoid long wait at each epoch transition.geth implements automatic DAG generation and maintains two DAGS at a time for smooth epoch transitions.