proof_of_work.rb

require 'digest'

NUM_ZEROES = 6

class Block
  def find_nonce(message)
    nonce = "HELP I'M TRAPPED IN A NONCE FACTORY"
    count = 0
    until valid_nonce?(nonce, message)
      print '.' if count % 10_000 == 0
      nonce = nonce.succ
      count += 1
    end
    puts "\nTotal: #{count}"
    nonce
  end

  def valid_nonce?(nonce, message)
    hash(message + nonce).start_with?("0" * NUM_ZEROES)
  end

  private

  def hash(message)
    Digest::SHA256.hexdigest(message)
  end
end

block = Block.new
nonce = block.find_nonce("lorem ipsum")
puts "Nonce: #{nonce}"