# Mining Bitcoins With Pencil And Paper

Right now there are thousands of computers connected to the Internet, dutifully calculating SHA-256 hashes and sending their results to other peers on the Bitcoin network. There’s a tremendous amount of computing power in this network, but [Ken] is doing it with a pencil and paper. Doing the math by hand isn’t exactly hard, but it does take an extraordinary amount of time; [Ken] can calculate about two-thirds of a hash per day.

The SHA-256 hash function used for Bitcoin isn’t really that hard to work out by hand.Â The problem, though, is that it takes a 64 byte value, sends it through an algorithm, and repeats that sixty-four times. There are a few 32-bit additions, but the rest of the work is just choosing the majority value in a set of three bits, rotating bits, and performing a mod 2.

Completing one round of a SHA-256 hash took [Ken] sixteen minutes and forty-five seconds. There are sixty-four steps in calculating the hash, this means a single hash would take about 18 hours to complete. Since Bitcoin uses a double SHA-256 algorithm, doing the calculations on a complete bitcoin block and submitting them to the network manually would take the better part of two days. If you’re only doing this as your daily 9-5, this is an entire weeks worth of work.

Just for fun, [Ken] tried to figure out how energy-efficient the bitcoin mining rig stored in his skull is. He can’t live on electricity, but donuts are a cheap source of calories, at about \$0.23 per 200 kcalories. Assuming a metabolic rate of 1500 kcal/day, this means his energy cost is about 67 quadrillion times that of an ASIC miner.

Video below.

## 17 thoughts on “Mining Bitcoins With Pencil And Paper”

Inefficient perhaps, but at least Dixon actually delivers their pencils.
#butterflylabs

2. Russ says:

Not only that, but you don’t submit each hash you calculate, you only submit hashes that have enough leading zeros. The chance that a hash would have only one leading (hex) zero is 1/16. Currently mined blocks have 16 leading hex zeros, that’ one hash in 2^64 hashes. (mining pools accept somewhat more common hashes for partial credit)

3. but unlike a computer, [Ken] will feel a bit sad (or hungry) if the hash comes out to 0xDEADBEEF

1. Dex hamilton says:

Sudoku Is a game of numbers that increases happieness when completeing…….

4. Anonymous says:

Too bad he can’t use GPGPU acceleration. Image and pattern recognition take a lot more processing power than simple math, and the brain can do that instinctively.

5. Dex hamilton says:

Funny this article and the one about CCN are conected ,http://cs.brown.edu/people/anna/papers/ltt04.pdf I Googled CNN and hash page 3 of the pdf contains this statement “Graph-Based Authentication. Graph-based authentication [12, 19, 22, 27] generalizes the idea of amortizing a signature over a hash chain in such a way as to tolerate packet losses.” HMMMMMMM very interesting HACKADAY

6. Hirudinea says:

So his cost is 67 quadrillion times that of a bit coin mining machine? Would he be cheaper if we sent him to China?

1. theo says:

Not exactly, his energy consumption, while higher, is only 6-7 times that of a computer. He’s just a ton slower!

7. marcus says:

interesting..great post.

8. Mark says:

So mining “by hand” should be worth more :-)

1. CMH62 says: