ShellFish is a Selfish Mining simulator that uses the Monte Carlo method to test the viability of Selfish Mining. It is written in JavaScript and its main goal is to reveal once and for all whether Selfish Mining poses any practical threats to the security of Bitcoin.
While abstract mathematics may be useful for exploring theoretical implications of even more theoretical conditions, a down-to-earth experiment is necessary to bring some clarity into view. The main feature of this software is to simulate the aspect of luck in the mining process as well as possible. For that reason, ShellFish includes a difficulty adjustment algorithm in its implementation and the virtual miners actually try to solve the mining puzzle to find new blocks.
In its current configuration, the selfish mining pool (named ShellFishPool) owns 47% of the global hashing power. If the simulator runs for until 15000 blocks get mined, it becomes obvious that the selfish mining pool has gained ownership over 50% of blocks. These results are consistent regardless of hown many times the simulation is executed. In fact, it is the nature of the Monte Carlo method to produce progressively more precise results as the simulation keeps running.
On the other hand, if the selfish mining pool controls only 42.5% of the global hashing power then their block ownership in the final block chain is also 42.5%, as expected by the security model of Bitcoin. According to this simulator, any hashing power less than 42% results in even lesser ownership of the resulting block chain. This means that Selfish Mining with the hashing power lesser than 42% is in fact helping the honest miners and is thus counterproductive for the selfish miner.
Since any single entity controlling more than 43% of the global hashing power is already a huge threat for the whole network even without Selfish Mining, it is clear that Selfish Mining is a non-issue. At the point where a single entity has accumulated such a large proportion of mining power, the Bitcoin network already has bigger fish to fry than the potential threat from Selfish Mining.
Below are the results from running the simulator with different parameters. Each test was conducted 4 times due to variance. The block chain ownership percentage seen in the below table is thus the average value of 4 independent tests for each row. This table illustrates how many blocks in the final block chain were mined by the selfish miner at different levels of control over the total hashing power of the network.
| Hashing Power | Block Share |
|---|---|
| 47% | 50% |
| 46% | 49% |
| 45% | 48% |
| 44% | 45% |
| 43% | 43% |
| 42% | 42% |
| 41% | 40% |
| 37% | 33% |
| 33% | 27% |
Quick demo here: https://jsfiddle.net/ksfx0dou/
ShellFishPool hides block 15379->15380 at 663s (00000011001001000110010011101100 / 11111100110100111110010000101010 / -244530, 15 BPS)!
ShellFishPool hides block 15380->15381 at 663s (00000000101001011011100110000010 / 11111100110100000001011100111011 / -249071, 15 BPS)!
ShellFishPool hides block 15381->15382 at 663s (00000001111110000010010101010101 / 11111100110011001010100001101010 / -224977, 16 BPS)!
ShellFishPool hides block 15382->15383 at 664s (00000010011111111101000111110011 / 11111100110010001011111110010011 / -256215, 16 BPS)!
ShellFishPool hides block 15383->15384 at 664s (00000001000011111110001000101111 / 11111100110001001100011001110010 / -260385, 16 BPS)!
HonestMinings found block 15379->15385 at 664s (00000010011111101110010011010110 / 11111100110100011010011100100011 / -391225, 15 BPS).
ShellFishPool reveals 2 hidden blocks and has mined 50% of blocks with 47% of hashing power.
ShellFishPool hides block 15384->15386 at 664s (00000001101000010100010101110011 / 11111100110000001100001111010101 / -262813, 16 BPS)!
HonestMinings found block 15381->15387 at 664s (00000000001101110011001001011110 / 11111100110010100110001111111100 / -373567, 15 BPS).
ShellFishPool reveals 2 hidden blocks and has mined 50% of blocks with 47% of hashing power.
ShellFishPool hides block 15386->15388 at 664s (00000010100010100111111011101100 / 11111100101111001011001011101101 / -266472, 16 BPS)!
ShellFishPool hides block 15388->15389 at 664s (00000000111110111101001000111110 / 11111100101110001111101010111101 / -243760, 16 BPS)!
ShellFishPool hides block 15389->15390 at 664s (00000000000001100001011101110101 / 11111100101101010011010111001100 / -247025, 16 BPS)!
ShellFishPool hides block 15390->15391 at 664s (00000001111011101110011000100110 / 11111100101100001110110000100001 / -281003, 16 BPS)!
HonestMinings found block 15383->15392 at 664s (00000001111100011100110100011000 / 11111100110000010010000110010010 / -499201, 15 BPS).
ShellFishPool reveals 2 hidden blocks and has mined 50% of blocks with 47% of hashing power.
ShellFishPool hides block 15391->15393 at 664s (00000011001110001111101011101010 / 11111100101011000001011111111110 / -316451, 16 BPS)!
ShellFishPool hides block 15393->15394 at 664s (00000011001111011100001110001001 / 11111100101001111010011101000001 / -291005, 16 BPS)!
ShellFishPool hides block 15394->15395 at 664s (00000000101011111010010010010010 / 11111100101000110010010111101000 / -295257, 16 BPS)!
HonestMinings found block 15386->15396 at 664s (00000000101000001101001101101010 / 11111100101110010000010011110010 / -507619, 15 BPS).
ShellFishPool reveals 2 hidden blocks and has mined 50% of blocks with 47% of hashing power.
HonestMinings found block 15389->15397 at 664s (00000001001001110000111111000001 / 11111100101100011110111000100011 / -461978, 15 BPS).
ShellFishPool reveals 2 hidden blocks and has mined 50% of blocks with 47% of hashing power.
ShellFishPool hides block 15395->15398 at 664s (00000010000111111111010100111011 / 11111100100111011001110100001101 / -362715, 15 BPS)!
ShellFishPool hides block 15398->15399 at 664s (00000000110101011111101001110111 / 11111100100110011110000101011110 / -244655, 16 BPS)!
ShellFishPool hides block 15399->15400 at 664s (00000001101110100000101101101110 / 11111100100101010001111101110010 / -311788, 16 BPS)!
ShellFishPool hides block 15400->15401 at 664s (00000010111100000011100110011110 / 11111100100100000100010001100111 / -318219, 16 BPS)!
ShellFishPool hides block 15401->15402 at 664s (00000010010111011111100011010010 / 11111100100010111011011111111010 / -298093, 16 BPS)!
ShellFishPool hides block 15402->15403 at 664s (00000010001101000011001000001110 / 11111100100001101001111010110010 / -334152, 16 BPS)!
ShellFishPool hides block 15403->15404 at 664s (00000000101011000000101110100011 / 11111100100000010111001011001001 / -338921, 16 BPS)!
HonestMinings found block 15391->15405 at 664s (00000010011100011100010110110100 / 11111100101001100111101011101101 / -684340, 15 BPS).
ShellFishPool reveals 2 hidden blocks and has mined 50% of blocks with 47% of hashing power.
HonestMinings found block 15394->15406 at 664s (00000011010010100000110001010100 / 11111100100111011111000010000111 / -636602, 15 BPS).
ShellFishPool reveals 2 hidden blocks and has mined 50% of blocks with 47% of hashing power.
ShellFishPool hides block 15404->15407 at 664s (00000001001100110101110010110011 / 11111100011110111011001010011001 / -376880, 16 BPS)!
HonestMinings found block 15398->15408 at 664s (00000001011011101110100111100100 / 11111100100101011000111011110101 / -527896, 15 BPS).
ShellFishPool reveals 2 hidden blocks and has mined 50% of blocks with 47% of hashing power.
ShellFishPool hides block 15407->15409 at 664s (00000000110101010100101110110110 / 11111100011101011101111101100110 / -381747, 16 BPS)!
ShellFishPool hides block 15409->15410 at 664s (00000001001011100110011000000101 / 11111100011100000111100001010001 / -354069, 16 BPS)!
HonestMinings found block 15400->15411 at 664s (00000000000000100011110100011001 / 11111100100010110110101110010001 / -635873, 15 BPS).
ShellFishPool reveals 2 hidden blocks and has mined 50% of blocks with 47% of hashing power.
ShellFishPool hides block 15410->15412 at 664s (00000001000111110001010011111100 / 11111100011010101111001100100101 / -361772, 16 BPS)!
ShellFishPool hides block 15412->15413 at 664s (00000000011101011010101000011100 / 11111100011001010110001000011111 / -364806, 16 BPS)!
ShellFishPool hides block 15413->15414 at 664s (00000001010101111101010111011110 / 11111100010111111011101010110111 / -370536, 16 BPS)!
ShellFishPool hides block 15414->15415 at 665s (00000001110011100010110000010110 / 11111100010110011111000111011011 / -379100, 16 BPS)!
ShellFishPool hides block 15415->15416 at 665s (00000001100000000100010000011101 / 11111100010101000000011010011011 / -387904, 16 BPS)!
HonestMinings found block 15402->15417 at 665s (00000001100111011001111110010101 / 11111100011111111100011101010010 / -782504, 15 BPS).
ShellFishPool reveals 2 hidden blocks and has mined 50% of blocks with 47% of hashing power.
ShellFishPool hides block 15416->15418 at 665s (00000001011000111000010110000101 / 11111100010011100000011001101011 / -393264, 16 BPS)!
HonestMinings found block 15404->15419 at 665s (00000000100001110000100100001000 / 11111100011101011100001111100101 / -765668, 15 BPS).
ShellFishPool reveals 2 hidden blocks and has mined 50% of blocks with 47% of hashing power.
HonestMinings found block 15409->15420 at 665s (00000010100111010011000101100001 / 11111100011010110111011110110100 / -681906, 15 BPS).
ShellFishPool reveals 2 hidden blocks and has mined 50% of blocks with 47% of hashing power.
HonestMinings found block 15412->15421 at 665s (00000001111100000000110000101111 / 11111100011000010101000110101100 / -631161, 15 BPS).
ShellFishPool reveals 2 hidden blocks and has mined 50% of blocks with 47% of hashing power.
HonestMinings found block 15414->15422 at 665s (00000000001101011110100001100000 / 11111100010101100101011010011111 / -615448, 15 BPS).
ShellFishPool reveals 2 hidden blocks and has mined 50% of blocks with 47% of hashing power.
ShellFishPool hides block 15418->15423 at 665s (00000010000010010111100110111101 / 11111100010001011101011101010100 / -536343, 15 BPS)!
HonestMinings found block 15416->15424 at 665s (00000001111111010001011100011101 / 11111100010010101110001110011111 / -598780, 15 BPS).
ShellFishPool reveals 2 hidden blocks and has mined 50% of blocks with 47% of hashing power.
Base58: 1Erich1YUdkUAp9ynf4Rfw2ug8nBtuUmMu
CashAddr: QZVQPSVVET3CPPU9Y0PE8L4ALPHQJCS09URP9RUJDH