Blockchain Lite (JavaScript Edition)

blockchain-lite library / module - build your own blockchain with crypto hashes - revolutionize the world with blockchains, blockchains, blockchains one block at a time

• home :: github.com/openblockchains/blockchain.lite.js
• bugs :: github.com/openblockchains/blockchain.lite.js/issues
• npm :: npmjs.com/package/blockchain-lite

What's a Blockchain?

A blockchain is a distributed database with a list (that is, chain) of records (that is, blocks) linked and secured by digital fingerprints (that is, crypto hashes).

See the Awesome Blockchains page for more.

Usage

Let's get started. Build your own blockchain one block at a time. Example:

const Blocks = require( "blockchain-lite" )

// use basic block
let Block = Blocks.basic

let b0 = Block.first( 'Genesis' )
let b1 = Block.next( b0, 'Transaction Data...' )
let b2 = Block.next( b1, 'Transaction Data......' )
let b3 = Block.next( b2, 'More Transaction Data...' )

let blockchain = [b0, b1, b2, b3]

console.log( blockchain )

will log something like:

[ Block {
    index: 0,
    timestamp: 2017-09-25 17:03:38,
    data: 'Genesis',
    previousHash: '0',
    hash: '08f4fa71628c5bc6b430228738bc8c41afaf508ece0b1cf9c9cac53d02e11829' },
  Block {
    index: 1,
    timestamp: 2017-09-25 17:13:38,
    data: 'Transaction Data...',
    previousHash: '08f4fa71628c5bc6b430228738bc8c41afaf508ece0b1cf9c9cac53d02e11829',
    hash: '740a4aeb3441484c96d1e7f63d31b716220ccee3b6fe94547cae2afbb6010626' },
  Block {
    index: 2,
    timestamp: 2017-09-25 17:23:38,
    data: 'Transaction Data......',
    previousHash: '740a4aeb3441484c96d1e7f63d31b716220ccee3b6fe94547cae2afbb6010626',
    hash: '28b6892a069e2ff7f1c3128ab495d7cd9b9b1636a51a7f69db93a14b1ee6b1a7' },
  Block {
    index: 3,
    timestamp: 2017-09-25 17:33:38,
    data: 'More Transaction Data...',
    previousHash: '28b6892a069e2ff7f1c3128ab495d7cd9b9b1636a51a7f69db93a14b1ee6b1a7',
    hash: '4cc0329b2c0cb32e0451fa3179bd944d4cd0fcf410939172f979e9fd2aa9f5f3' } ]

Blocks

Basic • Proof-of-Work

Supported block types / classes for now include:

Basic

class Block {

  constructor(index, data, previousHash) {
    this.index        = index
    this.timestamp    = new Date()
    this.data         = data
    this.previousHash = previousHash
    this.hash         = this.calcHash()
  }

  calcHash() {
    var sha = SHA256.create()
    sha.update( this.index.toString() +
                this.timestamp.toString() +
                this.data +
                this.previousHash )
    return sha.hex()
  }
  ...
}

(Source: block-basic.js)

Proof-of-Work

class Block {

  constructor(index, data, previousHash) {
    this.index              = index
    this.timestamp          = new Date()
    this.data               = data
    this.previousHash       = previousHash
    [this.nonce,this.hash]  = this.computeHashWithProofOfWork()
  }

  calcHash() {
    var sha = SHA256.create()
    sha.update( this.nonce.toString() +
                this.index.toString() +
                this.timestamp.toString() +
                this.data +
                this.previousHash )
    return sha.hex()
  }
  ...
}

(Source: block-proof-of-work.js)

Transactions

Let's put the transactions from the (hyper) ledger book from Tulips on the Blockchain! on the blockchain:

| From | To | What | Qty | |---------------------|--------------|---------------------------|----:| | Dutchgrown (†) | Vincent | Tulip Bloemendaal Sunset | 10 | | Keukenhof (†) | Anne | Tulip Semper Augustus | 7 | | | | | | | Flowers (†) | Ruben | Tulip Admiral van Eijck | 5 | | Vicent | Anne | Tulip Bloemendaal Sunset | 3 | | Anne | Julia | Tulip Semper Augustus | 1 | | Julia | Luuk | Tulip Semper Augustus | 1 | | | | | | | Bloom & Blossom (†) | Daisy | Tulip Admiral of Admirals | 8 | | Vincent | Max | Tulip Bloemendaal Sunset | 2 | | Anne | Martijn | Tulip Semper Augustus | 2 | | Ruben | Julia | Tulip Admiral van Eijck | 2 | | | | | | | Teleflora (†) | Max | Tulip Red Impression | 11 | | Anne | Naomi | Tulip Bloemendaal Sunset | 1 | | Daisy | Vincent | Tulip Admiral of Admirals | 3 | | Julia | Mina | Tulip Admiral van Eijck | 1 |

(†): Grower Transaction - New Tulips on the Market!

let b0 = Block.first(
        { from: "Dutchgrown", to: "Vincent", what: "Tulip Bloemendaal Sunset", qty: 10 },
        { from: "Keukenhof",  to: "Anne",    what: "Tulip Semper Augustus",    qty: 7  } )

let b1 = Block.next( b0,
        { from: "Flowers", to: "Ruben", what: "Tulip Admiral van Eijck",  qty: 5 },
        { from: "Vicent",  to: "Anne",  what: "Tulip Bloemendaal Sunset", qty: 3 },
        { from: "Anne",    to: "Julia", what: "Tulip Semper Augustus",    qty: 1 },
        { from: "Julia",   to: "Luuk",  what: "Tulip Semper Augustus",    qty: 1 } )

let b2 = Block.next( b1,
        { from: "Bloom & Blossom", to: "Daisy",   what: "Tulip Admiral of Admirals", qty: 8 },
        { from: "Vincent",         to: "Max",     what: "Tulip Bloemendaal Sunset",  qty: 2 },
        { from: "Anne",            to: "Martijn", what: "Tulip Semper Augustus",     qty: 2 },
        { from: "Ruben",           to: "Julia",   what: "Tulip Admiral van Eijck",   qty: 2 } )
...

resulting in:

[ Block {
    index:     0,
    timestamp: 1637-09-25 17:39:21,
    data:
     [ { from: 'Dutchgrown', to: 'Vincent',  what: 'Tulip Bloemendaal Sunset', qty: 10 },
       { from: 'Keukenhof',  to: 'Anne',     what: 'Tulip Semper Augustus',    qty: 7 } ],
    previousHash: '0',
    hash:         '7cb2df9eee29ca77c99eb4591a25dcbdfa9609aff2bd3558d1a0fe22acd08a51' },
  Block {
    index:     1,
    timestamp: 1637-09-25 17:49:21,
    data:
     [ { from: 'Flowers',  to: 'Ruben',  what: 'Tulip Admiral van Eijck',   qty: 5 },
       { from: 'Vicent',   to: 'Anne',   what: 'Tulip Bloemendaal Sunset',  qty: 3 },
       { from: 'Anne',     to: 'Julia',  what: 'Tulip Semper Augustus',     qty: 1 },
       { from: 'Julia',    to: 'Luuk',   what: 'Tulip Semper Augustus',     qty: 1 } ],
    previousHash: '7cb2df9eee29ca77c99eb4591a25dcbdfa9609aff2bd3558d1a0fe22acd08a51',
    hash:         'a7464e98290039f467e7abf6699180205f5151e76b57a79b39f43acc39d75660' },
  Block {
    index:     2,
    timestamp: 1637-09-25 17:59:21,
    data:
     [ { from: 'Bloom & Blossom', to: 'Daisy',    what: 'Tulip Admiral of Admirals', qty: 8 },
       { from: 'Vincent',         to: 'Max',      what: 'Tulip Bloemendaal Sunset',  qty: 2 },
       { from: 'Anne',            to: 'Martijn',  what: 'Tulip Semper Augustus',     qty: 2 },
       { from: 'Ruben',           to: 'Julia',    what: 'Tulip Admiral van Eijck',   qty: 2 } ],
    previousHash: 'a7464e98290039f467e7abf6699180205f5151e76b57a79b39f43acc39d75660',
    hash:         'b7e4952f801651c1e14d61d77b869d18268b46c468923089f1da33e3959b56b9' },
  ...
]

Install

Add the the module to your package e.g.:

$ npm install --save blockchain-lite

-or-

$ yarn add blockchain-lite

License

The blockchain.lite scripts are dedicated to the public domain. Use it as you please with no restrictions whatsoever.