base32.rb

class String
  Base32Alphabet ||= ('A'..'Z').to_a+%w[2 3 4 5 6 7]
  def base32
    binary   = unpack("B*").first
    binary  << "0"*(5-(binary.length % 5))
    decoded  = binary.scan(/.{1,5}/).map { |r| Base32Alphabet[r.to_i(2)] }.join('')
    decoded << "="*(8-(binary.length.div(5) % 8))
    decoded
  end
end