Ruby Proof of Work example

hash.rb

require 'optparse'
require_relative './proof_of_work'

options = {}
OptionParser.new do |opts|
  opts.on('--input INPUT', 'Input data') { |v| options[:input] = v }
  opts.on('--difficulty DIFFICULTY', 'Difficulty (leading zeroes)') { |v| options[:difficulty] = v }
end.parse!

start_time = Time.now

hash, nonce = ProofOfWork.hash_with_proof_of_work(options[:input], options[:difficulty])

puts
puts "Hashed data: #{options[:input]}"
puts "With difficulty: #{options[:difficulty]}"

puts
puts "Found nonce: #{nonce}"
puts "Result: #{hash}"
puts "Time to find nonce: #{Time.now - start_time} s"

proof_of_work.rb

require 'digest'

module ProofOfWork
  def self.hash_with_proof_of_work(data, difficulty)
    0.upto(Float::INFINITY) do |nonce_candidate|
      result = hash(data, nonce_candidate)
      puts result

      return [result, nonce_candidate] if result.start_with?(difficulty)
    end
  end

  def self.hash(data, nonce)
    sha = Digest::SHA256.new
    sha.update(nonce.to_s + data)
    sha.hexdigest
  end
end

verify.rb

require 'optparse'
require_relative './proof_of_work'

options = {}
OptionParser.new do |opts|
  opts.on('--input INPUT', 'Input data') { |v| options[:input] = v }
  opts.on('--hash HASH', 'Hash') { |v| options[:hash] = v }
  opts.on('--nonce NONCE', 'Nonce') { |v| options[:nonce] = v }
end.parse!

hash = ProofOfWork.hash(options[:input], options[:nonce])

puts "Hashed data: #{options[:input]}"
puts "Given hash: #{options[:hash]}"
puts "Given nonce: #{options[:nonce]}"
puts

if hash == options[:hash]
  puts "Verified that given nonce is valid proof of work."
else
  puts "Given nonce is invalid, no proof of work."
end