A method object to create crytographically safe seeds and strings.

Seed.js

/* I MADE THIS, I THINK ITS AWESOME */

/* Seed generation and shuffle */
var Seed_int = 0;
var Seed_str = '';
var Seed = {
    /* Generate a random number, or perpetuate
       a pseudo-random seed if it is provided. */
    random_int : function(seed_int){
        var rand = 0;
        if(typeof seed_int == 'number'){
            // A linear congruential generator
            var multiplier = 1103515245;
            var increment = 12345;
            var modulus = Math.pow(2, 31); // 2^31
            rand = ((multiplier * seed_int + increment) % modulus );
            //seed_int++;
        }else{
            // Create seed
            if(typeof window.crypto !== 'undefined' 
            && typeof window.crypto.getRandomValues === 'function'){
                // Sweeet crypto API
                var rand_arr = new Uint32Array(1);
                window.crypto.getRandomValues(rand_arr);
                rand = rand_arr[0];
            }else{
                // Insecure!
                rand = Math.floor(Math.random() * 10000000000);
            }
        }
        return rand;
    },

    /* Can generate an integer from a string. */
    int_from_string : function(str){
        var hash = 0;
        var len = str.length;
        if (len == 0) return hash;
        for (i = 0; i < len; i++) {
            var ch = str.charCodeAt(i);
            hash = ( (hash << 5) - hash) + ch;
            hash = hash & hash; // Convert to 32bit integer
        }
        return hash;
    },


    /*
        - len is desired string length 
        - corpus is the available characters to construct the output
        - seed is a number */
    string_from_seed : function(len, corpus, seed){
        var text = '';
        // Make sure corpus is at len lenght.
        if(len > corpus.length){ 
            for (var i = 0; i < len; i++) {
                corpus += corpus.charAt(i);
            };
        }
        return Seed.shuffle_string(corpus, seed).substring(0, len);
    },

    /*
        - corpus: the string to shuffle
        - seed: is an integer */
    shuffle_string : function(corpus, seed) {
        var a = corpus.split(''),
            n = a.length;

        for(var i = n - 1; i > 0; i--) {
            var j = Seed.random_int(seed) % (i + 1);
            var tmp = a[i];
            a[i] = a[j];
            a[j] = tmp;
        }
        return a.join('');
    },

    /* reset seed globals */
    reset_seed : function(){
        Seed_int = 0;
        Seed_str = '';
    },

    set_seed : function(seed_obj){
        Seed_str = seed_obj.str;
        Seed_int = seed_obj.int;
        return seed_obj;
    },

    make_seed_str : function(len,corpus){
        //Seed.reset_seed();
        return Seed.string_from_seed(len, corpus, Seed.random_int());
    },
};