Secure random number generation for Ruby using system RNG facilities e.g. /dev/urandom, getrandom(2)
System/OS-level random number generators like /dev/urandom and getrandom(2)
provide the best option for generating cryptographically secure random numbers.
Ruby's built-in SecureRandom does not provide this, but instead uses OpenSSL's userspace RNG. This has been a source of vulnerabilities in Ruby, and this Ruby bug ticket contains more discussion on the issue.
This gem aims to solve the problem.
In cryptography circles, the prevailing advice is to use OS RNG functionality,
namely /dev/urandom or equivalent calls which use an OS-level CSPRNG to
produce random numbers.
This gem provides an easy-to-install repackaging of the randombytes
functionality from libsodium for the purpose of generating secure random
numbers trustworthy for use in cryptographic contexts, such as generating
cryptographic keys, initialization vectors, or nonces.
The following random number generators are utilized:
| Platform | RNG |
|---|---|
| Linux | getrandom(2) if available, otherwise /dev/urandom |
| Windows | RtlGenRandom CryptGenRandom without CryptoAPI deps |
| OpenBSD | arc4random(3) with ChaCha20 CSPRNG (not RC4) |
| JRuby | NativePRNGNonBlocking on Java 8, otherwise SHA1PRNG |
| Others | /dev/urandom |
Sysrandom is tested on the following Ruby implementations:
- Ruby (MRI) 2.0, 2.1, 2.2, 2.3
- JRuby 9.1.1.0
Add this line to your application's Gemfile:
gem 'sysrandom'And then execute:
$ bundle
Or install it yourself as:
$ gem install sysrandom
Sysrandom aims to be API-compatible with Ruby's built-in SecureRandom class,
but always prefers OS-level RNG wherever it's available:
>> Sysrandom.random_number(42)
=> 15
>> Sysrandom.random_bytes(32)
=> "\xD6J\xB3\xD2\x8B\x7F*9D\xB7\xF9\xEA\xE2\\\xAAH\tV#\xEC\x84\xE3E\r\x97\xB9\b\xFCH\x17\xA0\v"
>> Sysrandom.base64(32)
=> "WXPkxfAuLRpnI6Z4zFb4E+MIenx6w6vKhe01+rMPuIQ="
>> Sysrandom.urlsafe_base64(32)
=> "37rsMfR4X8g7Bb-uDJEekRHnB3r_7nO03cv52ilaWqE="
>> Sysrandom.hex(32)
=> "c950496ce200abf7d18eb1414e9206c6335f971a37d0394114f56439b59831ba"
>> Sysrandom.uuid
=> "391c6f52-8017-4838-9790-131a9b979c63"Since Sysrandom is SecureRandom-compatible, it can be patched in-place of SecureRandom if you prefer its RNG behavior.
To do this, require sysrandom/securerandom:
>> SecureRandom
=> SecureRandom
>> require "sysrandom/securerandom"
=> true
>> SecureRandom
=> Sysrandom
>> SecureRandom.hex(32)
=> "d1bbe8c1ab78fc2fe514c5623d913a27ffd2dcdc9e002f3b358bb01a996962f1"- Fork this repository on Github
- Make your changes and send a pull request
- If your changes look good, we'll merge them
Copyright (c) 2013-2017 Frank Denis, Tony Arcieri. See LICENSE.txt for further details.