rc4

rc4

RC4 random number generator

Synopsis

var RC4 = require("rc4");

var generator = new RC4("my seed"); // string or array of integers
// without the seed RNG is seeded with random data from Math.random

// byte := integer ∈ [0, 255]
console.log(generator.randomByte());

// float := number ∈ [0, 1)
console.log(generator.randomFloat());

// save & load state
var state = generator.currentState();
console.log(generator.randomFloat()); // 0.14815412228927016
generator.setState(state);
console.log(generator.randomFloat()); // 0.14815412228927016

RC4small

There is also RC4small generator, with smaller internal state:

var RC4small = require("rc4").RC4small;

var generator = new RC4small("my seed");

var stateString = generator.currentStateString(); // 18 character hexadecimal string
console.log(generator.randomFloat());  // 0.9362740234937519
generator.setStateString(stateString);
console.log(generator.randomFloat()); // 0.9362740234937519

API

Both RC4 and RC4small have following random value generating methods:

randomByte   : () ⇒ { x : ℕ | x ∈ [0, 255] }
randomUInt32 : () ⇒ { x : ℕ | x ∈ [0, 2^32-1] }
randomFloat  : () ⇒ { x : R | x ∈ [0, 1) }
random       : (a : ℤ)        ⇒ { x : ℤ | x ∈ [0, a] }
random       : (a : ℤ, b : ℤ) ⇒ { x : ℤ | x ∈ [a, b] }