mode-ctr-gladman.js

;(function (root, factory, undef) {
	if (typeof exports === "object") {
		// CommonJS
		module.exports = exports = factory(require("./core"), require("./cipher-core"));
	}
	else if (typeof define === "function" && define.amd) {
		// AMD
		define(["./core", "./cipher-core"], factory);
	}
	else {
		// Global (browser)
		factory(root.CryptoJS);
	}
}(this, function (CryptoJS) {

	/** @preserve
	 * Counter block mode compatible with  Dr Brian Gladman fileenc.c
	 * derived from CryptoJS.mode.CTR
	 * Jan Hruby jhruby.web@gmail.com
	 */
	CryptoJS.mode.CTRGladman = (function () {
	    var CTRGladman = CryptoJS.lib.BlockCipherMode.extend();

		function incWord(word)
		{
			if (((word >> 24) & 0xff) === 0xff) { //overflow
			var b1 = (word >> 16)&0xff;
			var b2 = (word >> 8)&0xff;
			var b3 = word & 0xff;

			if (b1 === 0xff) // overflow b1
			{
			b1 = 0;
			if (b2 === 0xff)
			{
				b2 = 0;
				if (b3 === 0xff)
				{
					b3 = 0;
				}
				else
				{
					++b3;
				}
			}
			else
			{
				++b2;
			}
			}
			else
			{
			++b1;
			}

			word = 0;
			word += (b1 << 16);
			word += (b2 << 8);
			word += b3;
			}
			else
			{
			word += (0x01 << 24);
			}
			return word;
		}

		function incCounter(counter)
		{
			if ((counter[0] = incWord(counter[0])) === 0)
			{
				// encr_data in fileenc.c from  Dr Brian Gladman's counts only with DWORD j < 8
				counter[1] = incWord(counter[1]);
			}
			return counter;
		}

	    var Encryptor = CTRGladman.Encryptor = CTRGladman.extend({
	        processBlock: function (words, offset) {
	            // Shortcuts
	            var cipher = this._cipher
	            var blockSize = cipher.blockSize;
	            var iv = this._iv;
	            var counter = this._counter;

	            // Generate keystream
	            if (iv) {
	                counter = this._counter = iv.slice(0);

	                // Remove IV for subsequent blocks
	                this._iv = undefined;
	            }

				incCounter(counter);

				var keystream = counter.slice(0);
	            cipher.encryptBlock(keystream, 0);

	            // Encrypt
	            for (var i = 0; i < blockSize; i++) {
	                words[offset + i] ^= keystream[i];
	            }
	        }
	    });

	    CTRGladman.Decryptor = Encryptor;

	    return CTRGladman;
	}());




	return CryptoJS.mode.CTRGladman;

}));