module SecureRandom

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.

If a secure random number generator is not available, NotImplementedError is raised.

Public Class Methods

bytes(n) click to toggle source
# File securerandom.rb, line 42
def bytes(n)
  return gen_random(n)
Alias for: gen_random_openssl

Private Class Methods

gen_random_openssl(n) click to toggle source
# File securerandom.rb, line 48
def gen_random_openssl(n)
  @pid = 0 unless defined?(@pid)
  pid = $$
  unless @pid == pid
    now = Process.clock_gettime(Process::CLOCK_REALTIME, :nanosecond)
    OpenSSL::Random.random_add([now, @pid, pid].join(""), 0.0)
    seed = Random.urandom(16)
    if (seed)
      OpenSSL::Random.random_add(seed, 16)
    @pid = pid
  return OpenSSL::Random.random_bytes(n)
Also aliased as: gen_random
gen_random_urandom(n) click to toggle source
# File securerandom.rb, line 63
def gen_random_urandom(n)
  ret = Random.urandom(n)
  unless ret
    raise NotImplementedError, "No random device"
  unless ret.length == n
    raise NotImplementedError, "Unexpected partial read from random device: only #{ret.length} for #{n} bytes"
Also aliased as: gen_random