Module: SecureRandom

Defined in:
lib/securerandom.rb

Overview

Secure random number generator interface.

This library is an interface to secure random number generators which are suitable for generating session keys in HTTP cookies, etc.

You can use this library in your application by requiring it:

require 'securerandom'

It supports the following secure random number generators:

  • openssl

  • /dev/urandom

  • Win32

SecureRandom is extended by the Random::Formatter module which defines the following methods:

  • alphanumeric

  • base64

  • choose

  • gen_random

  • hex

  • rand

  • random_bytes

  • random_number

  • urlsafe_base64

  • uuid

These methods are usable as class methods of SecureRandom such as `SecureRandom.hex`.

Examples

Generate random hexadecimal strings:

require 'securerandom'

SecureRandom.hex(10) #=> "52750b30ffbc7de3b362"
SecureRandom.hex(10) #=> "92b15d6c8dc4beb5f559"
SecureRandom.hex(13) #=> "39b290146bea6ce975c37cfc23"

Generate random base64 strings:

SecureRandom.base64(10) #=> "EcmTPZwWRAozdA=="
SecureRandom.base64(10) #=> "KO1nIU+p9DKxGg=="
SecureRandom.base64(12) #=> "7kJSM/MzBJI+75j8"

Generate random binary strings:

SecureRandom.random_bytes(10) #=> "\016\t{\370g\310pbr\301"
SecureRandom.random_bytes(10) #=> "\323U\030TO\234\357\020\a\337"

Generate alphanumeric strings:

SecureRandom.alphanumeric(10) #=> "S8baxMJnPl"
SecureRandom.alphanumeric(10) #=> "aOxAg8BAJe"

Generate UUIDs:

SecureRandom.uuid #=> "2d931510-d99f-494a-8c67-87feb05e1594"
SecureRandom.uuid #=> "bad85eb9-0713-4da7-8d36-07a8e4b00eab"

Class Method Summary collapse

Class Method Details

.bytes(n) ⇒ Object


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# File 'lib/securerandom.rb', line 72

def bytes(n)
  return gen_random(n)
end

.gen_random(n) ⇒ Object


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# File 'lib/securerandom.rb', line 76

def gen_random(n)
  ret = Random.urandom(1)
  if ret.nil?
    begin
      require 'openssl'
    rescue NoMethodError
      raise NotImplementedError, "No random device"
    else
      @rng_chooser.synchronize do
        class << self
          remove_method :gen_random
          alias gen_random gen_random_openssl
          public :gen_random
        end
      end
      return gen_random(n)
    end
  else
    @rng_chooser.synchronize do
      class << self
        remove_method :gen_random
        alias gen_random gen_random_urandom
        public :gen_random
      end
    end
    return gen_random(n)
  end
end