Blockchain Lite

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

What's a Blockchain?

A blockchain is a 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:

require 'blockchain-lite'

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

blockchain = [b0, b1, b2, b3]

pp blockchain

will pretty print (pp) something like:

[#<Block:0x1eed2a0
  @index              = 0,
  @timestamp          = 2021-09-15 20:52:38,
  @transactions_count = 1,
  @transactions       = ["Genesis"],
  @previous_hash      = "0",
  @hash               = "edbd4e11e69bc399a9ccd8faaea44fb27410fe8e3023bb9462450a0a9c4caa1b">,
 #<Block:0x1eec9a0
  @index              = 1,
  @timestamp          = 2021-09-15 21:02:38,
  @transactions_count = 1,
  @transactions       = ["Transaction Data..."],
  @hash               = "eb8ecbf6d5870763ae246e37539d82e37052cb32f88bb8c59971f9978e437743",
  @previous_hash      = "edbd4e11e69bc399a9ccd8faaea44fb27410fe8e3023bb9462450a0a9c4caa1b">,
 #<Block:0x1eec838
  @index              = 2,
  @timestamp          = 2021-09-15 21:12:38,
  @transactions_count = 1,
  @transactions       = ["Transaction Data..."],
  @hash               = "be50017ee4bbcb33844b3dc2b7c4e476d46569b5df5762d14ceba9355f0a85f4",
  @previous_hash      = "eb8ecbf6d5870763ae246e37539d82e37052cb32f88bb8c59971f9978e437743">,
 #<Block:0x1eec6d0
  @index              = 3,
  @timestamp          = 2021-09-15 21:22:38
  @transactions_count = 1,
  @transactions       = ["Transaction Data..."],
  @hash               = "5ee2981606328abfe0c3b1171440f0df746c1e1f8b3b56c351727f7da7ae5d8d",
  @previous_hash      = "be50017ee4bbcb33844b3dc2b7c4e476d46569b5df5762d14ceba9355f0a85f4">]

Blocks

Basic • Proof-of-Work

Supported block types / classes for now include:

Basic

class Block

  attr_reader :index
  attr_reader :timestamp
  attr_reader :transactions_count
  attr_reader :transactions
  attr_reader :previous_hash
  attr_reader :hash

  def initialize(index, transactions, previous_hash)
    @index              = index
    @timestamp          = Time.now.utc    ## note: use coordinated universal time (utc)
    @transactions       = transactions
    @transactions_count = transactions.size
    @previous_hash      = previous_hash
    @hash               = calc_hash
  end

  def calc_hash
    sha = Digest::SHA256.new
    sha.update( @timestamp.to_s +
                @transactions.to_s +
                @previous_hash )
    sha.hexdigest
  end
  ...
end

(Source: basic/block.rb)

Proof-of-Work

class Block

  attr_reader :index
  attr_reader :timestamp
  attr_reader :transactions_count
  attr_reader :transactions
  attr_reader :transactions_hash    ## merkle_root
  attr_reader :previous_hash
  attr_reader :nonce        ## proof of work if hash starts with leading zeros (00)
  attr_reader :hash

  def initialize(index, transactions, previous_hash)
    @index              = index
    @timestamp          = Time.now.utc    ## note: use coordinated universal time (utc)
    @transactions       = transactions
    @transactions_count = transactions.size
    @transactions_hash  = MerkleTree.compute_root_for( transactions )
    @previous_hash      = previous_hash
    @nonce, @hash       = compute_hash_with_proof_of_work
  end

  def calc_hash
    sha = Digest::SHA256.new
    sha.update( @nonce.to_s +
                @timestamp.to_s +
                @transactions_hash +
                @previous_hash )
    sha.hexdigest
  end
  ...
end

(Source: proof_of_work/block.rb)

Blockchain Helper / Convenience Wrapper

The Blockchain class offers some convenience helpers for building and checking blockchains. Example:

b = Blockchain.new       # note: will (auto-) add the first (genesis) block

b << 'Transaction Data...'
b << 'Transaction Data...'
b << 'Transaction Data...'

pp b

Check for broken chain links. Example:


b.broken?
# => false      ## blockchain OK

or use the Blockchain class as a wrapper (pass in the blockchain array):

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

blockchain = [b0, b1, b2, b3]


b = Blockchain.new( blockchain )

b.broken?
# => false      ## blockchain OK

and so on.

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!

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

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 } )

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:0x2da3da0
  @index              = 0,
  @timestamp          = 1637-09-24 11:40:15,
  @previous_hash      = "0",
  @hash               = "32bd169baebba0b70491b748329ab631c85175be15e1672f924ca174f628cb66",
  @transactions_count = 2,
  @transactions       =
   [{:from=>"Dutchgrown", :to=>"Vincent", :what=>"Tulip Bloemendaal Sunset", :qty=>10},
    {:from=>"Keukenhof",  :to=>"Anne",    :what=>"Tulip Semper Augustus",    :qty=>7}]>,
 #<Block:0x2da2ff0
  @index              = 1,
  @timestamp          = 1637-09-24 11:50:15,
  @previous_hash      = "32bd169baebba0b70491b748329ab631c85175be15e1672f924ca174f628cb66",
  @hash               = "57b519a8903e45348ac8a739c788815e2bd90423663957f87e276307f77f1028",
  @transactions_count = 4,
  @transactions       =
   [{: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}]>,
 #<Block:0x2da2720
  @index              = 2,
  @timestamp          = 1637-09-24 12:00:15,
  @previous_hash      = "57b519a8903e45348ac8a739c788815e2bd90423663957f87e276307f77f1028",
  @hash               = "ec7dd5ea86ab966d4d4db182abb7aa93c7e5f63857476e6301e7e38cebf36568",
  @transactions_count = 4,
  @transactions       =
   [{: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}]>,
 ...

Blockchain Lite in the Real World

  • centralbank - command line tool (and core library) - print your own money / cryptocurrency; run your own federated central bank nodes on the blockchain peer-to-peer over HTTP; revolutionize the world one block at a time
  • tulipmania - command line tool (and core library) - tulips on the blockchain; learn by example from the real world (anno 1637) - buy! sell! hodl! enjoy the beauty of admiral of admirals, semper augustus, and more; run your own hyper ledger tulip exchange nodes on the blockchain peer-to-peer over HTTP; revolutionize the world one block at a time
  • You? Add your tool / service

References

Programming Cryptocurrencies and Blockchains (in Ruby) by Gerald Bauer et al, 2018, Yuki & Moto Press

And many more @ Best of Crypto Books - a collection of books, white papers & more about crypto and blockchains

License

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