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.

Constant Summary

VERSION =

The version

# File 'lib/securerandom.rb', line 44
```
"0.4.1"
```

Class Method Summary

.alphanumeric(n = nil, chars: ALPHANUMERIC)

Compatibility methods for Ruby 3.2, we can remove this after dropping to support Ruby 3.2.
.bytes(n)

Returns a random binary string containing size bytes.
.gen_random_openssl(n) private Internal use only

Implementation using OpenSSL.
.gen_random_urandom(n) private Internal use only

Implementation using system random device.

Class Method Details

.alphanumeric(n = nil, chars: ALPHANUMERIC)

Compatibility methods for Ruby 3.2, we can remove this after dropping to support Ruby 3.2

[ GitHub ]

# File 'lib/securerandom.rb', line 55


def alphanumeric(n = nil, chars: ALPHANUMERIC)
  n = 16 if n.nil?
  choose(chars, n)
end

.bytes(n)

Returns a random binary string containing size bytes.

See Random.bytes

[ GitHub ]

# File 'lib/securerandom.rb', line 50


def bytes(n)
  return gen_random(n)
end

.gen_random_openssl(n) (private)

This method is for internal use only.

Implementation using OpenSSL

[ GitHub ]

# File 'lib/securerandom.rb', line 65


def gen_random_openssl(n)
  return OpenSSL::Random.random_bytes(n)
end

.gen_random_urandom(n) (private)

This method is for internal use only.

Implementation using system random device

[ GitHub ]

# File 'lib/securerandom.rb', line 70


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