crackme solution in ruby

cracker.rb

require "benchmark"

class Cracker
  
  class << self  
  
    ## runs the code retuning sek runtime
    def run(test)
      Benchmark.realtime{`./crackme #{test}`}
    end

    # asuming the key is shorter then 100 chars
    def get_size
      1000.times do |i| 
        test = 'a'*i
        time = run(test)
        if time > 0.1
          return i
        end
      end
    end

    def chars
    ('A'..'Z').to_a + ('a'..'z').to_a + ('0'..'9').to_a
    end

    # we now have an array an check against each position to get the last (size -1) characters
    def get_first(pass)
    time = run(pass.join(''))
    (pass.size-1).downto(1) do |i|
      (chars.size).times do |j|
        pass[i] = chars[j]
        t = run(pass.join(''))
        if  t > (time + 0.08)
          time = t
          break
        end    
      end
    end
      return pass[1..-1].join('')    
    end

    # only one (the first char is left)
    def get_full_pass(first_part)
      chars.each do |char|
        test=char+first_part
        res = `./crackme #{test}`
        unless res.match(/Wrong/)
          return test
        end
      end
      'could not find any password'
    end

    def give_me_da_fucking_password
      size = get_size
      seed = ['-'] * size
      first = get_first(seed)
      get_full_pass(first)
    end
  end   
end