Class: RandomRDRand

• Inheritance
• Description
• Class protocol
  • instance creation
  • queries
• Instance protocol
  • initialization
  • random numbers

Inheritance:

   Object
   |
   +--RandomRDRand

Package:

stx:libbasic2

Category:

Magnitude-Numbers-Random

Version:

rev: 1.13 date: 2021/01/20 15:59:35

user: cg

file: RandomRDRand.st directory: libbasic2

module: stx stc-classLibrary: libbasic2

Description:

This generator uses the rdgen random generator which is built into modern intel chips.
Before using, you should check via the isSupported query.

Warning:
    there have been discussions about the security of the intel rdgen instruction
    and whether there are NSA backdoors built into it.
    Linus Torwalds refuses to use it for /dev/urandom in the linux kernel, for that very reason.
    Be sure you know what you are doing, if you use this generator for sensitive cryptographic stuff.
    We recommend using one of the libcrypt-based generators and use this only to get additional
    entropy for the seed.

Warning2:
    the initial release of the AMD Ryzen3000 (without BIOS update) has a bug in returning the same
    (all 1s) random number every time.
    The code here checks for that an raises an error in the constructor if that bug is detected.
    Be sure to catch this exception in your code and fall back to another random generator if raised.
    
NO WARRANTY

[usage:]
    RandomRDRand new nextInteger

copyright
COPYRIGHT (c) 2014 Claus Gittinger
             All Rights Reserved

This software is furnished under a license and may be used
only in accordance with the terms of that license and with the
inclusion of the above copyright notice.   This software may not
be provided or otherwise made available to, or used by, any
other person.  No title to or ownership of the software is
hereby transferred.

Class protocol:

 new

self new nextInteger

 new: seed

seed is actually ignored

 isSupported

true if this architecture supports hardware random numbers

Usage example(s):

self isSupported

Instance protocol:

 initialize

check for Ryzen RDRAND bug (returning the same all-ones everytime)

 seed: seed

ignored

 nextBoolean

generates a boolean random

Usage example(s):

|bag rng| rng := self new. bag := Bag new. 100000 timesRepeat:[ bag add:rng nextBoolean. ]. bag

 nextInteger

generates the next integer in 0..MAXINT.
Notice, it may raise an illegal instruction exception on some cpu chips,
even though the cpuid instruction says that it is available

Usage example(s):

self new nextInteger