TinyMT32 Pseudorandom Number Generator (PRNG)
RFC 8682

Document Type RFC - Proposed Standard (January 2020; No errata)
Authors Mutsuo Saito  , Makoto Matsumoto  , Vincent Roca  , Emmanuel Baccelli 
Last updated 2020-01-14
Replaces draft-roca-tsvwg-tinymt32
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Stream WG state Submitted to IESG for Publication
Document shepherd Wesley Eddy
Shepherd write-up Show (last changed 2019-04-18)
IESG IESG state RFC 8682 (Proposed Standard)
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Responsible AD Magnus Westerlund
Send notices to Wesley Eddy <wes@mti-systems.com>
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Internet Engineering Task Force (IETF)                          M. Saito
Request for Comments: 8682                                  M. Matsumoto
Category: Standards Track                           Hiroshima University
ISSN: 2070-1721                                             V. Roca, Ed.
                                                             E. Baccelli
                                                                   INRIA
                                                            January 2020

             TinyMT32 Pseudorandom Number Generator (PRNG)

Abstract

   This document describes the TinyMT32 Pseudorandom Number Generator
   (PRNG), which produces 32-bit pseudorandom unsigned integers and aims
   at having a simple-to-use and deterministic solution.  This PRNG is a
   small-sized variant of the Mersenne Twister (MT) PRNG.  The main
   advantage of TinyMT32 over MT is the use of a small internal state,
   compatible with most target platforms that include embedded devices,
   while keeping reasonably good randomness that represents a
   significant improvement compared to the Park-Miller Linear
   Congruential PRNG.  However, neither the TinyMT nor MT PRNG is meant
   to be used for cryptographic applications.

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8682.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction
     1.1.  Requirements Language
   2.  TinyMT32 PRNG Specification
     2.1.  TinyMT32 Source Code
     2.2.  TinyMT32 Usage
     2.3.  Specific Implementation Validation and Deterministic
           Behavior
   3.  Security Considerations
   4.  IANA Considerations
   5.  References
     5.1.  Normative References
     5.2.  Informative References
   Acknowledgments
   Authors' Addresses

1.  Introduction

   This document specifies the TinyMT32 PRNG as a specialization of the
   reference implementation version 1.1 (2015/04/24) by Mutsuo Saito and
   Makoto Matsumoto from Hiroshima University, which can be found at
   [TinyMT-web] (the TinyMT website) and [TinyMT-dev] (the GitHub site).
   This specialization aims at having a simple-to-use and deterministic
   PRNG, as explained below.  However, the TinyMT32 PRNG is not meant to
   be used for cryptographic applications.

   TinyMT is a new, small-sized variant of the Mersenne Twister (MT)
   PRNG introduced in 2011 [MT98].  This document focuses on the
   TinyMT32 variant (rather than TinyMT64) of the TinyMT PRNG, which
   outputs 32-bit unsigned integers.

   The purpose of TinyMT is not to replace the Mersenne Twister: TinyMT
   has a far shorter period (2^(127) - 1) than MT.  The merit of TinyMT
   is in the small size of the 127-bit internal state, far smaller than
   the 19937 bits of MT.  The outputs of TinyMT satisfy several
   statistical tests for non-cryptographic randomness, including
   BigCrush in TestU01 [TestU01] and AdaptiveCrush [AdaptiveCrush],
   leaving it well placed for non-cryptographic usage, especially given
   the small size of its internal state (see [TinyMT-web]).  From this
   point of view, TinyMT32 represents a major improvement with respect
   to the Park-Miller Linear Congruential PRNG (e.g., as specified in
   [RFC5170]), which suffers from several known limitations (see, for
   instance, [PTVF92], Section 7.1, p. 279 and [RFC8681], Appendix B).

   The TinyMT32 PRNG initialization depends, among other things, on a
   parameter set, namely (mat1, mat2, tmat).  In order to facilitate the
   use of this PRNG and to make the sequence of pseudorandom numbers
   depend only on the seed value, this specification requires the use of
   a specific parameter set (see Section 2.1).  This is a major
   difference with respect to the implementation version 1.1
   (2015/04/24), which leaves this parameter set unspecified.
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