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- goog.provide('goog.crypt.Arc4');
- goog.require('goog.asserts');
- goog.crypt.Arc4 = function() {
-
- this.state_ = [];
-
- this.index1_ = 0;
-
- this.index2_ = 0;
- };
- goog.crypt.Arc4.prototype.setKey = function(key, opt_length) {
- goog.asserts.assertArray(key, 'Key parameter must be a byte array');
- if (!opt_length) {
- opt_length = key.length;
- }
- var state = this.state_;
- for (var i = 0; i < 256; ++i) {
- state[i] = i;
- }
- var j = 0;
- for (var i = 0; i < 256; ++i) {
- j = (j + state[i] + key[i % opt_length]) & 255;
- var tmp = state[i];
- state[i] = state[j];
- state[j] = tmp;
- }
- this.index1_ = 0;
- this.index2_ = 0;
- };
- goog.crypt.Arc4.prototype.discard = function(length) {
- var i = this.index1_;
- var j = this.index2_;
- var state = this.state_;
- for (var n = 0; n < length; ++n) {
- i = (i + 1) & 255;
- j = (j + state[i]) & 255;
- var tmp = state[i];
- state[i] = state[j];
- state[j] = tmp;
- }
- this.index1_ = i;
- this.index2_ = j;
- };
- goog.crypt.Arc4.prototype.crypt = function(data, opt_length) {
- if (!opt_length) {
- opt_length = data.length;
- }
- var i = this.index1_;
- var j = this.index2_;
- var state = this.state_;
- for (var n = 0; n < opt_length; ++n) {
- i = (i + 1) & 255;
- j = (j + state[i]) & 255;
- var tmp = state[i];
- state[i] = state[j];
- state[j] = tmp;
- data[n] ^= state[(state[i] + state[j]) & 255];
- }
- this.index1_ = i;
- this.index2_ = j;
- };
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