NodeCoin

Implementation of Bitcoin / cryptocurrency using NodeJS

Resources

• A blockchain in 200 loc - Medium piece

• Naivecoin: tutorial to build blockchain - actually pretty good

• Pycoin - Bitcoin implementation in Python

• First Commit by Satoshi Nakamoto

• Research into Elliptic Curve Cryptography

• Basic TCP/IP Networking in Node JS

• Mastering Bitcoin - great book on Bitcoin protocols

Getting Started

The following dependencies must be installed before running:

• MongoDB - you can follow the installation instructions here. You will want a db called "nodecoin" that you can access.

• NPM - Node Package Manager - make sure you are on the latest version of NodeJS

Then install the JavaScript dependencies:

npm install

Simply run the start-up script:

npm start

This will add your computer to the pool of computers running NodeCoin. You should see a connection message, after which the program will sync with other computers.

Creating an Address

Once the program is running, in a separate terminal tab, type:

curl -XGET localhost:3000/wallets | python -m json.tool

This will provide all currently available wallet addresses and their balance. If you have not made a transaction, yours will not show up here.

For a specific wallet balance and unspent transaction outputs (UTXO), type:

curl -XGET localhost:3000/wallets/1Nd85AnFYDtaQAG6vF9FVWXFWksG5HuA3M | python -m json.tool

Here you can replace "1Nd85AnFYDtaQAG6vF9FVWXFWksG5HuA3M" with "WALLET_ADDRESS"

You can also generate a new wallet:

curl -XPOST localhost:3000/wallets/new | python -m json.tool

This will provide you with a new:

• privateKey
• publicKey
• publicKeyHash (sha-256 encrypted version of public key)
• privateKeyWif ("WIF" (wallet-import-format) version of private key)
• address (base58-encoded version of publicKeyHash)

You can use the private and public keys to send and recieve NodeCoin.

To send money (the example send 10 satoshis):

curl -XPOST localhost:3000/send -d publicKey=044283eb5f9aa7421f646f266fbf5f7a72b7229a7b90a088d1fe45292844557b1d80ed9ac96d5b3ff8286e7794e05c28f70ae671c7fecd634dd278eb0373e6a3ba -d amount=10 -d privateKey=0fcb37c77f68a69b76cd5b160ac9c85877b4e8a09d8bcde2c778715c27f9a347 -d toAddress=0482a39675cdc06766af5192a551b703c5090fc67f6e403dfdb42b60d34f5e3539ad44de9197e7ac09d1db5a60f79552ce5c7984a3fc4643fb1911f3857d6dd34c | python -m json.tool

Development

To work on the project, the following is recommended:

In one terminal screen, run the compiler:

npm run dev

In another terminal screen, you can run the updated build via:

npm start

The compiler will listen for changes and will update the code immediately. You may have to restart the npm start service for changes to take effect.

Redux

We use redux for local variable storage (get/set behavior)

MongoDB

We use a local MongoDB to store blocks. We can also keep track of UTXO (unspent transaction outputs).

Transactions that are not yet added to the block can be added to the mempool.

Orphan transactions can be added to the orphan transaction pool.

Further, we can create balances for users (by wallet address)

Seed transactions

# check friend balance
curl -XGET localhost:3000/wallets/1PDLNfJq5GAEn5StESZuBpaBe6B3134vmD

# send 10 NTC to friend
curl -XPOST localhost:3000/send -d publicKey=044283eb5f9aa7421f646f266fbf5f7a72b7229a7b90a088d1fe45292844557b1d80ed9ac96d5b3ff8286e7794e05c28f70ae671c7fecd634dd278eb0373e6a3ba -d amount=10 -d privateKey=0fcb37c77f68a69b76cd5b160ac9c85877b4e8a09d8bcde2c778715c27f9a347 -d toAddress=04804a9ed2855fcea0f5b6e23e587a6c6f7159f15c84b9c82474231cfdac04827fac72a36bd0b463fc61c4d66a954aa7d5f95bde970804f81c8d6f712390516fbb | python -m json.tool

# friend send 2 NTC back
curl -XPOST localhost:3000/send -d publicKey=04804a9ed2855fcea0f5b6e23e587a6c6f7159f15c84b9c82474231cfdac04827fac72a36bd0b463fc61c4d66a954aa7d5f95bde970804f81c8d6f712390516fbb -d amount=2 -d privateKey=6128428978e30fc034c95b7b091b373b875bdd73a0acf83c09d37bff72361349 -d toAddress=044283eb5f9aa7421f646f266fbf5f7a72b7229a7b90a088d1fe45292844557b1d80ed9ac96d5b3ff8286e7794e05c28f70ae671c7fecd634dd278eb0373e6a3ba | python -m json.tool