/**

 * Crypto

 * 

 * An abstraction layer to instanciate our crypto algorithms

 * Copyright (c) 2007 Henri Torgemane

 * 

 * See LICENSE.txt for full license information.

 */

package com.hurlant.crypto

{

	import com.hurlant.crypto.hash.HMAC;

	import com.hurlant.crypto.hash.MAC;

	import com.hurlant.crypto.hash.IHash;

	import com.hurlant.crypto.hash.MD2;

	import com.hurlant.crypto.hash.MD5;

	import com.hurlant.crypto.hash.SHA1;

	import com.hurlant.crypto.hash.SHA224;

	import com.hurlant.crypto.hash.SHA256;

	import com.hurlant.crypto.prng.ARC4;

	import com.hurlant.crypto.rsa.RSAKey;

	import com.hurlant.crypto.symmetric.AESKey;

	import com.hurlant.crypto.symmetric.BlowFishKey;

	import com.hurlant.crypto.symmetric.CBCMode;

	import com.hurlant.crypto.symmetric.CFB8Mode;

	import com.hurlant.crypto.symmetric.CFBMode;

	import com.hurlant.crypto.symmetric.CTRMode;

	import com.hurlant.crypto.symmetric.DESKey;

	import com.hurlant.crypto.symmetric.ECBMode;

	import com.hurlant.crypto.symmetric.ICipher;

	import com.hurlant.crypto.symmetric.IMode;

	import com.hurlant.crypto.symmetric.IPad;

	import com.hurlant.crypto.symmetric.ISymmetricKey;

	import com.hurlant.crypto.symmetric.IVMode;

	import com.hurlant.crypto.symmetric.NullPad;

	import com.hurlant.crypto.symmetric.OFBMode;

	import com.hurlant.crypto.symmetric.PKCS5;

	import com.hurlant.crypto.symmetric.SimpleIVMode;

	import com.hurlant.crypto.symmetric.TripleDESKey;

	import com.hurlant.crypto.symmetric.XTeaKey;

	import com.hurlant.util.Base64;

	import flash.utils.ByteArray;

	/**

	 * A class to make it easy to use the rest of the framework.

	 * As a side-effect, using this class will cause most of the framework

	 * to be linked into your application, which is not always what you want.

	 * 

	 * If you want to optimize your download size, don't use this class.

	 * (But feel free to read it to get ideas on how to get the algorithm you want.)

	 */

	public class Crypto

	{

		private var b64:Base64; // we don't use it, but we want the swc to include it, so cheap trick.

		public function Crypto(){

		}

		/**

		 * Things that should work, among others:

		 *  "aes"

		 *  "aes-128-ecb"

		 *  "aes-128-cbc"

		 *  "aes-128-cfb"

		 *  "aes-128-cfb8"

		 *  "aes-128-ofb"

		 *  "aes-192-cfb"

		 *  "aes-256-ofb"

		 *  "blowfish-cbc"

		 *  "des-ecb"

		 *  "xtea"

		 *  "xtea-ecb"

		 *  "xtea-cbc"

		 *  "xtea-cfb"

		 *  "xtea-cfb8"

		 *  "xtea-ofb"

		 *  "rc4"

		 *  "simple-aes-cbc"

		 */

		public static function getCipher(name:String, key:ByteArray, pad:IPad=null):ICipher {

			// split name into an array.

			var keys:Array = name.split("-");

			switch (keys[0]) {

				/**

				 * "simple" is a special case. It means:

				 * "If using an IV mode, prepend the IV to the ciphertext"

				 */

				case "simple":

					keys.shift();

					name = keys.join("-");

					var cipher:ICipher = getCipher(name, key, pad);

					if (cipher is IVMode) {

						return new SimpleIVMode(cipher as IVMode);

					} else {

						return cipher;

					}

				/**

				 * we support both "aes-128" and "aes128"

				 * Technically, you could use "aes192-128", but you'd

				 * only be hurting yourself.

				 */

				case "aes":

				case "aes128":

				case "aes192":

				case "aes256":

					keys.shift();

					if (key.length*8==keys[0]) {

						// support for "aes-128-..." and such.

						keys.shift();

					}

					return getMode(keys[0], new AESKey(key), pad);

				break;

				case "bf":

				case "blowfish":

					keys.shift();

					return getMode(keys[0], new BlowFishKey(key), pad);

				/**

				 * des-ede and des-ede3 are both equivalent to des3.

				 * the choice between 2tdes and 3tdes is made based

				 * on the length of the key provided.

				 */

				case "des":

					keys.shift();

					if (keys[0]!="ede" && keys[0]!="ede3") {

						return getMode(keys[0], new DESKey(key), pad);

					}

					if (keys.length==1) {

						keys.push("ecb"); // default mode for 2tdes and 3tdes with openssl enc

					}

					// fall-through to triple des

				case "3des":

				case "des3":

					keys.shift();

					return getMode(keys[0], new TripleDESKey(key), pad);

				case "xtea":

					keys.shift();

					return getMode(keys[0], new XTeaKey(key), pad);

				break;

				/**

				 * Technically, you could say "rc4-128" or whatever,

				 * but really, the length of the key is what counts here.

				 */

				case "rc4":

					keys.shift();

					return new ARC4(key);

				break;

			}

			return null;

		}

		/**

		 * Returns the size of a key for a given cipher identifier.

		 */

		public static function getKeySize(name:String):uint {

			var keys:Array = name.split("-");

			switch (keys[0]) {

				case "simple":

					keys.shift();

					return getKeySize(keys.join("-"));

				case "aes128":

					return 16;

				case "aes192":

					return 24;

				case "aes256":

					return 32;

				case "aes":

					keys.shift();

					return parseInt(keys[0])/8;

				case "bf":

				case "blowfish":

					return 16;

				case "des":

					keys.shift();

					switch (keys[0]) {

						case "ede":

							return 16;

						case "ede3":

							return 24;

						default:

							return 8;

					}

				case "3des":

				case "des3":

					return 24;

				case "xtea":

					return 8;

				case "rc4":

					if (parseInt(keys[1])>0) {

						return parseInt(keys[1])/8;

					}

					return 16; // why not.

			}

			return 0; // unknown;

		}

		private static function getMode(name:String, alg:ISymmetricKey, padding:IPad=null):IMode {

			switch (name) {

				case "ecb":

					return new ECBMode(alg, padding);

				case "cfb":

					return new CFBMode(alg, padding);

				case "cfb8":

					return new CFB8Mode(alg, padding);

				case "ofb":

					return new OFBMode(alg, padding);

				case "ctr":

					return new CTRMode(alg, padding);

				case "cbc":

				default:

					return new CBCMode(alg, padding);

			}

		}

		/**

		 * Things that should work:

		 * "md5"

		 * "sha"

		 * "sha1"

		 * "sha224"

		 * "sha256"

		 */

		public static function getHash(name:String):IHash {

			switch(name) {

				case "md2":

					return new MD2;

				case "md5":

					return new MD5;

				case "sha": // let's hope you didn't mean sha-0

				case "sha1":

					return new SHA1;

				case "sha224":

					return new SHA224;

				case "sha256":

					return new SHA256;

			}

			return null;

		}

		/**

		 * Things that should work:

		 * "sha1"

		 * "md5-64"

		 * "hmac-md5-96"

		 * "hmac-sha1-128"

		 * "hmac-sha256-192"

		 * etc.

		 */

		public static function getHMAC(name:String):HMAC {

			var keys:Array = name.split("-");

			if (keys[0]=="hmac") keys.shift();

			var bits:uint = 0;

			if (keys.length>1) {

				bits = parseInt(keys[1]);

			}

			return new HMAC(getHash(keys[0]), bits);

		}

		public static function getMAC(name:String):MAC {

			var keys:Array = name.split("-");

			if (keys[0]=="mac") keys.shift();

			var bits:uint = 0;

			if (keys.length > 1) {

				bits = parseInt(keys[1]);

			}

			return new MAC(getHash(keys[0]), bits);

		}

		public static function getPad(name:String):IPad {

			switch(name) {

				case "null":

					return new NullPad;

				case "pkcs5":

				default:

					return new PKCS5;

			}

		}

		/** mostly useless.

		 */

		public static function getRSA(E:String, M:String):RSAKey {

			return RSAKey.parsePublicKey(M,E);

		}

	}

}