schas002 · November 10, 2024 14:32 · username1565 · Sep 23, 2020 · Francois-Laberge-Bose · Sep 23, 2020
diff --git a/blum_blum_shub.js b/blum_blum_shub.js
 /**

 *** blum_blum_shub.js ***
 An implementation of the Blum Blum Shub pseudorandom number generator proposed 
 in 1986 by Lenore Blum, Manuel Blum and Michael Shub that is derived from 
 Michael O. Rabin's oblivious transfer mapping.

 Blum Blum Shub takes the form

            2
 	x    = x  mod M
 	 n+1    n

 where M = pq is the product of two large primes p and q. At each step of the 
 algorithm, some output is derived from x[n+1]; the output is commonly either 
 the bit parity of x[n+1] or one or more of the least significant bits of 
 x[n+1].

 The seed x[0] should be an integer that is co-prime to M (i.e. p and q are not 
 factors of x[0]) and not 1 or 0.

 The two primes, p and q, should both be congruent to 3 (mod 4) (this guarantees 
 that each quadratic residue has one square root which is also a quadratic 
 residue) and gcd(phi(p - 1), phi(q - 1)) should be small (this makes the cycle 
 length large).

 In this implementation, p = 5651 and q = 5623.

 This software is licensed under the zlib/libpng license:

 Copyright (c) 2016 Andrew Zyabin

 This software is provided 'as-is', without any express or implied warranty. In 
 no event will the authors be held liable for any damages arising from the use 
 of this software.

 Permission is granted to anyone to use this software for any purpose, including 
 commercial applications, and to alter it and redistribute it freely, subject to 
 the following restrictions:

    1. The origin of this software must not be misrepresented; you must not 
    claim that you wrote the original software. If you use this software in a 
    product, an acknowledgment in the product documentation would be 
    appreciated but is not required.

    2. Altered source versions must be plainly marked as such, and must not be 
    misrepresented as being the original software.

    3. This notice may not be removed or altered from any source distribution.

 */

 var p = 5651;
 var q = 5623;
 var M = p * q;

 var x = undefined;

 /** Get the gcd of two numbers, A and B. */
 function gcd(a, b) {
 	while(a != b) {
 		if(a > b) {
 			a = a - b;
 		} else {
 			b = b - a;
 		}
 	}
 	return a;
 }

 /** Seed the random number generator. */
 function seed(s) {
 	if(s == 0) {
 		throw new Error("The seed x[0] cannot be 0");
 	} else if(s == 1) {
 		throw new Error("The seed x[0] cannot be 1");
 	} else if(gcd(s, M) != 1) {
 		throw new Error("The seed x[0] must be co-prime to " + M.toString());
 	} else {
 		x = s;
 		return s;
 	}
 }

 /** Get next item from the random number generator. */
 function next() {
 	var cachedx = x;
 	cachedx = cachedx * x;
 	cachedx = cachedx % M;
 	x = cachedx;
 	return x;
 }
	/**

	* blum_blum_shub.js *
	An implementation of the Blum Blum Shub pseudorandom number generator proposed
	in 1986 by Lenore Blum, Manuel Blum and Michael Shub that is derived from
	Michael O. Rabin's oblivious transfer mapping.

	Blum Blum Shub takes the form

	2
	x = x mod M
	n+1 n

	where M = pq is the product of two large primes p and q. At each step of the
	algorithm, some output is derived from x[n+1]; the output is commonly either
	the bit parity of x[n+1] or one or more of the least significant bits of
	x[n+1].

	The seed x[0] should be an integer that is co-prime to M (i.e. p and q are not
	factors of x[0]) and not 1 or 0.

	The two primes, p and q, should both be congruent to 3 (mod 4) (this guarantees
	that each quadratic residue has one square root which is also a quadratic
	residue) and gcd(phi(p - 1), phi(q - 1)) should be small (this makes the cycle
	length large).

	In this implementation, p = 5651 and q = 5623.

	This software is licensed under the zlib/libpng license:

	Copyright (c) 2016 Andrew Zyabin

	This software is provided 'as-is', without any express or implied warranty. In
	no event will the authors be held liable for any damages arising from the use
	of this software.

	Permission is granted to anyone to use this software for any purpose, including
	commercial applications, and to alter it and redistribute it freely, subject to
	the following restrictions:

	1. The origin of this software must not be misrepresented; you must not
	claim that you wrote the original software. If you use this software in a
	product, an acknowledgment in the product documentation would be
	appreciated but is not required.

	2. Altered source versions must be plainly marked as such, and must not be
	misrepresented as being the original software.

	3. This notice may not be removed or altered from any source distribution.

	*/

	var p = 5651;
	var q = 5623;
	var M = p * q;

	var x = undefined;

	/** Get the gcd of two numbers, A and B. */
	function gcd(a, b) {
	while(a != b) {
	if(a > b) {
	a = a - b;
	} else {
	b = b - a;
	}
	}
	return a;
	}

	/** Seed the random number generator. */
	function seed(s) {
	if(s == 0) {
	throw new Error("The seed x[0] cannot be 0");
	} else if(s == 1) {
	throw new Error("The seed x[0] cannot be 1");
	} else if(gcd(s, M) != 1) {
	throw new Error("The seed x[0] must be co-prime to " + M.toString());
	} else {
	x = s;
	return s;
	}
	}

	/** Get next item from the random number generator. */
	function next() {
	var cachedx = x;
	cachedx = cachedx * x;
	cachedx = cachedx % M;
	x = cachedx;
	return x;
	}
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