Module: SecureRandom

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain: self, Random::Formatter
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.

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

Class Method Details

.bytes(n)

[ GitHub ]

# File 'lib/securerandom.rb', line 43


def bytes(n)
  return gen_random(n)
end

.gen_random_openssl(n) (private)

[ GitHub ]

# File 'lib/securerandom.rb', line 49


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)
    end
    @pid = pid
  end
  return OpenSSL::Random.random_bytes(n)
end

.gen_random_urandom(n) (private)

[ GitHub ]

# File 'lib/securerandom.rb', line 64


def gen_random_urandom(n)
  ret = Random.urandom(n)
  unless ret
    raise NotImplementedError, "No random device"
  end
  unless ret.length == n
    raise NotImplementedError, "Unexpected partial read from random device: only #{ret.length} for #{n} bytes"
  end
  ret
end