A web-based demonstration of blockchain concepts.
This is a very basic visual introduction to the concepts behind a blockchain. We introduce the idea of an immutable ledger using an interactive web demo that is available here:
http://andersbrownworth.com/blockchain/
Get the code:
git clone https://github.com/anders94/blockchain-demo.git
Install dependencies:
cd blockchain-demo
npm install
Run the server:
npm start
OR
./bin/www
#For windows: if the above command didn't work, use this (make sure you have Node.js installed in your system):
node ./bin/www
Point a web browser at the demo:
http://localhost:3000
Get the code:
git clone https://github.com/anders94/blockchain-demo.git
Run the Docker setup:
cd blockchain-demo
docker-compose up -d
Point a web browser at the demo:
http://localhost:3000
You can adjust the "number of zeros" required by the demo by editing the first two lines of
public/javascripts/blockchain.js.
Because there are 16 possible characters in a hex value, each time you increment the difficulty by one you make the puzzle 16 times harder. In my testing, a difficulty of 6 requires a maximumNonce well over 500,000,000.
If you adjust the difficulty above 4, blocks will show up as not mined because the demo data
assumes 4 zeros for a signed block. For example, on the http://localhost:3000/block page
with a difficulty of 6, the first nonce that works is 8719932 yielding a hash of
000000669445c22167511857d8f3b822b331c3342f25dfdcb326e35c1a7aa267. This gets out of hand fairly
quickly though. Here's some time estimates at the various thresholds.
| digits | nonce | time estimate |
|---|---|---|
| 4 | 500,000 | 15 minutes |
| 5 | 8,000,000 | 4 hours |
| 6 | 128,000,000 | 3 days |
| 7 | 2,048,000,000 | a month |
| 8 | 32,768,000,000 | 2 years |
| 9 | 524,288,000,000 | 30 years |
| 10 | 8,388,608,000,000 | 481 years |
| 11 | 134,217,728,000,000 | 7,690 years |
| 12 | 2,147,483,648,000,000 | 123,036 years |
| 13 | 34,359,738,368,000,000 | 1,968,581 years |
| 14 | 549,755,813,888,000,000 | 31,497,291 years |
| 15 | 8,796,093,022,208,000,000 | 503,956,662 years |
In the production bitcoin blockchain, block 458,091 has the hash digest
00000000000000000000011246f099d94f91628d71c9d75ad2f9a06e2beb7e92. That's 21 zeros in a row!
That one block would take this software approximately 8,454,989,768,407,765 years to mine.
The 2nd part of the 101 session:
Bitcoin gratefully accepted: 1K3NvcuZzVTueHW1qhkG2Cm3viRkh2EXJp