Mining Difficulty – How Difficulty is Related to Mining in Ethereum Blockchain?

From https://github.com/ethereum/EIPs/blob/master/EIPS/eip-2.md:

Mining difficulty is calculated from the time difference between blocks. The exact formula will change in Homestead. The symbol // in the following denotes integer division.

• Frontier:

block_diff = parent_diff + parent_diff // 2048 * (1 if block_timestamp - parent_timestamp < 13 else -1) + int(2**((block.number // 100000) - 2))

• Homestead:

block_diff = parent_diff + parent_diff // 2048 * max(1 - (block_timestamp - parent_timestamp) // 10, -99) + int(2**((block.number // 100000) - 2))

EDIT:

The problem with the frontier formula and the reason for the change was that the frontier version doesn't take into account how far off from 13 seconds the block time was. A block mined 1 second after the previous one has the same effect on the difficulty as one mined after 12 seconds. This causes block difficulty to adjust to a median block time rather than a mean.

Again, check out the EIP for more details.

There are 2 ways to do this:

• Change the value of difficulty parameter in genesis.json file to a small number(preferably set it to 0). You can refer to this example genesis file

  {
     "config": {
        "chainId": 1994,
        "homesteadBlock": 0,
        "eip155Block": 0,
        "eip158Block": 0,
        "byzantiumBlock": 0
     },
     "difficulty": "0x0", //difficulty set to zero in hexadecimal format
     "gasLimit": "0x8000000",
     "alloc": {
        "9a963d0eefeb62678d8efb48561c81e51c552797": { 
            "balance": "9606938044258990275541962092341162602522202993782792835301376" 
        },
        "30f28686aef33adbfbc13797b1d9f5a2f2759f56": { 
            "balance": "9606938044258990275541962092341162602522202993782792835301376" 
        }
     }
  }
  

Problem with this method is that when the block number increases, the difficulty also starts increasing at a high rate. So, to tackle that problem refer to the below part.

• You can reduce the rate of block difficulty increament by making some changes in the consensus code of go-ethereum. Open consensus.go which resides at consensus/ethash/consensus.go and search for the below line.

return CalcDifficulty(chain.Config(), time, parent)

Now replace the above line with the below one.

return big.NewInt(1).

Now build the go-ethereum using make geth command.

I strongly recommend you to go through this article for much detailed implementation of the above process.