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GRC's UHE PRNG in node (Ultra-High Entropy Pseudo-Random Number Generator by Gibson Research Corporation)


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Gibson Research Corporation's Ultra-High Entropy Pseudo-Random Number Generator ported to node.

The original library / project page is located here:

The node project page is here:

There were a few modifications made to the original library to allow seeding, and to pass jshint.

I've also added the following helper methods:

  • random()
  • range(range)
  • floatBetween(min, max)
  • intBetween(min, max)

Getting Started

Install the module with: npm install random-seed

var rand = require('random-seed').create();
var n = rand(100); // generate a random number between 0 - 99 


Create a random number generator

var gen = require('random-seed'); // create a generator 
// these generators produce different numbers 
var rand1 = gen.create(); // method 1 
var rand2 = new gen();    // method 2 
var rand3 = gen();        // method 3 
// these generators will produce 
// the same sequence of numbers 
var seed = 'My Secret String Value';
var rand4 = gen.create(seed);
var rand5 = new gen(seed);
var rand6 = gen(seed);

Random Generator Methods

Once a random generator is created, you have the following methods available.

I typically create a random generator like this:

var rand = require('random-seed').create();


Returns a random integer between 0 (inclusive) and range (exclusive)


Returns a random integer between 0 (inclusive) and range (exclusive)


Returns a random float between 0 (inclusive) and 1 (exclusive)

Works the same as Math.random()

rand.floatBetween(min, max)

Returns a random float between min (inclusive) and max (exclusive)

rand.intBetween(min, max)

Returns a random integer between min (inclusive) and max (inclusive)


Same as calling rand.initState() followed by rand.hashString(seed). If seed is not a string, then the seed value will be converted to a string. If you don't pass a seed argument, then the generator uses Math.random() as the seed.


Returns a pseudo-random string of 'count' printable characters ranging from chr(33) to chr(126) inclusive.


Removes leading and trailing spaces and non-printing control characters, including any embedded carriage-return (CR) and line-feed (LF) characters, from any string it is handed. This is also used by the 'hashstring' function (below) to help users always obtain the same EFFECTIVE uheprng seeding key.


Hashes the provided character string after first removing any leading or trailing spaces and ignoring any embedded carriage returns (CR) or Line Feeds (LF).

rand.addEntropy(/* accept zero or more arguments */)

This handy exported function is used to add entropy to our uheprng at any time.


If we want to provide a deterministic startup context for our PRNG, but without directly setting the internal state variables, this allows us to initialize the mash hash and PRNG's internal state before providing some hashing input.


We use this (optional) exported function to signal the JavaScript interpreter that we're finished using the internal "Mash" hash function so that it can free up the local "instance variables" it will have been maintaining. It's not strictly necessary, of course, but it's good JavaScript citizenship.


Default Usage: create 1 random number between 0 - 99

var rand = require('random-seed').create();
var n = rand(100); // generate a random number between 0 - 99 

Always create same sequence of random numbers

var rand = require('random-seed').create();
var n1 = rand(100); // n1 === 58 
var n2 = rand(100); // n2 === 26 
rand.initState();   // re-init 
var n3 = rand(100); // n3 === 58 && n3 === n1 

Create 2 random number generators

var rand1 = require('random-seed').create(),
    rand2 = require('random-seed').create();
console.log(rand1(100), rand2(100));

Create 2 random number generators with the same seed

var seed = 'Hello World',
    rand1 = require('random-seed').create(seed),
    rand2 = require('random-seed').create(seed);
console.log(rand1(100), rand2(100));

Replace Math.random()

var math = require('random-seed').create();

Release History

v0.2.0 (Released June 1, 2014)

  • Adding the following helper methods:
    • rand.random(min, max)
    • rand.floatBetween(min, max)
    • rand.intBetween(min, max)

v0.1.0 (Released October 26, 2013)

  • Initial Release


Copyright (c) 2013 skratchdot

Dual Licensed under the MIT license and the original Public Domain License by GRC.