random文字列

config/initializers/sessoin_store.rb
の:secretとか。

# ワンライナー
ruby -rsecurerandom -e 'puts SecureRandom.hex(16)'

#irb
require 'securerandom'
SecureRandom.hex(n) #default 16

中身はこんな感じ。

/opt/local/lib/ruby/1.8/securerandom.rb

  def self.hex(n=nil)
    random_bytes(n).unpack("H*")[0]
  end


  def self.random_bytes(n=nil)
    n ||= 16
    if defined? OpenSSL::Random
      return OpenSSL::Random.random_bytes(n)
    end
    if !defined?(@has_urandom) || @has_urandom
      @has_urandom = false
      flags = File::RDONLY
      flags |= File::NONBLOCK if defined? File::NONBLOCK
      flags |= File::NOCTTY if defined? File::NOCTTY
      flags |= File::NOFOLLOW if defined? File::NOFOLLOW
      begin
        File.open("/dev/urandom", flags) {|f|
          unless f.stat.chardev?
            raise Errno::ENOENT
          end
          @has_urandom = true
          ret = f.readpartial(n)
          if ret.length != n
            raise NotImplementedError, "Unexpected partial read from random device"
          end
          return ret
        }
      rescue Errno::ENOENT
        raise NotImplementedError, "No random device"
      end
    end
    raise NotImplementedError, "No random device"
  end