What is Ethash?

Ethash is the Proof-of-Work (PoW) consensus algorithm used to mine Ethereum’s native cryptocurrency, Ether. It is used to adjust the difficulty of the mining process.

Ethereum is a blockchain-based, open-technology platform that offers many opportunities for decentralization and digital development. Using smart contracts, developers can create decentralized applications (DApps). Ether, the native cryptocurrency on the Ethereum blockchain, can be used for various transactions.

Proof-of-Work mining that Ethereum 1.0 uses occurs by taking data from a block header, using it as an input, and hashing it via the cryptographic method. The outcome is a fixed-length output that determines the hash value. Once the data is submitted to initiate the process, Ether miners use new sequence numbers to hash different variants of the input data.

Ethash provides improvements on the prior version of Proof-of-Work mining, Dagger-Hashimoto, which required higher computational costs. Instead, Ethash uses a vast and expanding dataset that is compact enough for the VRAM of a GPU.

The hash value produced via Ethash must be below the provided threshold, which determines the difficulty. The Ethereum network regularly adjusts the threshold to be more or less difficult. This manages the mining pace – if the mining pace rises, the difficulty level is automatically increased and the threshold along with the number of valid hashes is lowered.

Similarly, if the mining pace slows down, the network increases the threshold. This leads to a higher number of discoverable valid hash values.

Ethash can help determine how many computing resources a miner requires to locate the sequence number, or nonce, which makes it possible to propose new blocks to be added to the chain. On average, a new block is generated every 12 seconds.

Miners often adjust the memory clock frequency of the GPU. This helps them yield more Ethash hash rates. This process produces more heat and requires higher electrical resources. Therefore, miners may rely on manually managing power control or setting their fans to higher speeds.

Those involved in Ether mining may build custom PCs containing six or more powerful GPUs. This helps achieve cost-effective mining. The strategy of using custom-built PCs is often employed by crypto mining farms.

The rewards for a successfully discovered block that can be added to the chain are:

• A static block reward (3 ETH);
• The gas fees of the mining process are covered by the execution of all transactions recorded in the block;
• Additional rewards for including stale blocks, or uncles, in the block.

Ethash is designed to be ASIC-resistant, thus making the overall process of mining Ether fairer.  It is expected that Ethereum 2.0 will move from Proof-of-Work to the Proof-of-Stake (PoS) consensus algorithm, taking the Ethash mechanism out of commission.