It is possible to mine Bitcoin with a pencil and a sheet of paper

Miner cryptocurrency is often compared to the resolution of a sudoku. The calculation of the hash that will form the new block can be found with a paper and a pencil. Here's how.

Bitcoins and Ethers are extracted using a cryptographic algorithm called SHA-256. This algorithm is sufficiently "simple" that to be solved with a pencil and paper, provided you have a mathematical mind, to be focused and applied.

Finding the hash is the essence of the transactions that occur on the blockchain. Miners must guess this 64-character sequence of digits and letters that will match the entire data in a block of information blockchain. Once the good hash is found, the transaction can be made.

The method of Ken Shirriff

To explain to neophytes how the algorithms that make up the block chain work, the mathematician Ken Shirrif has made a video showing how to find this hash. Here is his sharp explanation.

"I wrote each block A to H in hexadecimal on a separate line and put the binary value below it, the shift operation appears under C, and offsets and Σ0 appear above row A. the selection operation appears under G, and the shifts and Σ1 above E. At the bottom right, a set of terms is added: it corresponds to the first three boxes of the red sum. sum is used to generate the new value A and, in the middle right, this sum is used to generate the new value E. "  © Ken Shirriff

"I also manually performed another hash trick, the last trick to finish chopping the Bitcoin block." In the image below, the hash result is highlighted in yellow, and the zeros in this hash show that this hash is highlighted in yellow. is a successful hash, note that the zeros are at the end of the hash, the reason being that Bitcoin inconveniently reverses all the bytes generated by SHA-256. "  © Ken Shirriff

The manual method is a demonstration

"Taking a turn of SHA-256 by hand took me 16 minutes and 45 seconds at this rate, the hash of a full block of Bitcoin (128 rounds) would take 1.49 days, for a hash rate of 0.67 hash per day (although I should probably go faster with practice) .In comparison, the current Bitcoin operating hardware does several terahash per second, about a quintillion times faster than my manual hash. to say that manual exploitation of Bitcoin is not practical at all. "

Remember that mining machines can run up to 25 terahash per second. Either propose in one second, 25 x 1,000,000,000,000 hash. At this speed, it takes sometimes a year or more for a machine to find the hash that will release a block. Knowing that a human takes a day and a half to find a single hash, it appears that it is almost impossible for a human to mine Bitcoin with a pencil and a sheet of paper. Ken Shiriff concludes with a metaphor: "finding a functional hash is as hard as finding a grain of sand among all the grains of sand on Earth."