Hellbound Hackers Timed Challenge 4

main.rb

#!/usr/bin/ruby

require 'mechanize'
require 'io/console'

def decrypt(str)
  final = []
  for i in (0..str.length)
    i.odd? ? final << str[i-2] : final << str[i]
  end
  final.delete_at(-2) if str.length.odd?
  return final.join
end

print 'Username: '
name = gets.chomp
print 'Password: '
pass = STDIN.noecho(&:gets).chomp

client = Mechanize.new { |agent| agent.user_agent = 'Mechanize -- Ninjex' }
client.get('https://www.hellboundhackers.org/') do |page|
  page.form_with(:action => '//www.hellboundhackers.org/') do |f|
    f.user_name = name
    f.user_pass = pass
  end.click_button
end

client.get('https://www.hellboundhackers.org/challenges/timed/timed4/index.php') do |page|
  data = page.search('td[2] div strong').to_s.split('<strong>')[7]
  cipher = data.to_s.gsub('</strong>', '')
  answer = decrypt(cipher)
  page.form_with(:action => '/challenges/timed/timed4/index.php?check') {|f| f.ans = answer }.click_button
  puts answer
end