46 lines
1009 B
JavaScript
46 lines
1009 B
JavaScript
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// prng4.js - uses Arcfour as a PRNG
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function Arcfour() {
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this.i = 0;
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this.j = 0;
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this.S = new Array();
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}
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// Initialize arcfour context from key, an array of ints, each from [0..255]
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function ARC4init(key) {
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var i, j, t;
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for(i = 0; i < 256; ++i)
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this.S[i] = i;
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j = 0;
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for(i = 0; i < 256; ++i) {
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j = (j + this.S[i] + key[i % key.length]) & 255;
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t = this.S[i];
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this.S[i] = this.S[j];
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this.S[j] = t;
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}
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this.i = 0;
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this.j = 0;
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}
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function ARC4next() {
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var t;
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this.i = (this.i + 1) & 255;
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this.j = (this.j + this.S[this.i]) & 255;
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t = this.S[this.i];
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this.S[this.i] = this.S[this.j];
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this.S[this.j] = t;
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return this.S[(t + this.S[this.i]) & 255];
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}
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Arcfour.prototype.init = ARC4init;
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Arcfour.prototype.next = ARC4next;
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// Plug in your RNG constructor here
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function prng_newstate() {
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return new Arcfour();
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}
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// Pool size must be a multiple of 4 and greater than 32.
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// An array of bytes the size of the pool will be passed to init()
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var rng_psize = 256;
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