decrypttransformer.cs

AJAX开发工具包

using System;
using System.Security.Cryptography;

namespace AjaxPro.Cryptography
{
	/// <summary>
	/// 
	/// </summary>
	internal class DecryptTransformer
	{
		private EncryptionAlgorithm algorithmID;
		private byte[] initVec;

		public DecryptTransformer(EncryptionAlgorithm algId)
		{
			algorithmID = algId;
		}

		internal ICryptoTransform GetCryptoServiceProvider(byte[] bytesKey)
		{
			switch(algorithmID)
			{
				case EncryptionAlgorithm.Des:
					DES des = new DESCryptoServiceProvider();
					des.Mode = CipherMode.CBC;
					des.Key = bytesKey;
					des.IV = initVec;
					return des.CreateDecryptor();

				case EncryptionAlgorithm.TripleDes:
					TripleDES des3 = new TripleDESCryptoServiceProvider();
					des3.Mode = CipherMode.CBC;
					return des3.CreateDecryptor(bytesKey, initVec);

				case EncryptionAlgorithm.Rc2:
					RC2 rc2 = new RC2CryptoServiceProvider();
					rc2.Mode = CipherMode.CBC;
					return rc2.CreateDecryptor(bytesKey, initVec);

				case EncryptionAlgorithm.Rijndael:
					Rijndael rijndael = new RijndaelManaged();
					rijndael.Mode = CipherMode.CBC;
					return rijndael.CreateDecryptor(bytesKey, initVec);

				default:
					throw new CryptographicException("Algorithm ID '" + algorithmID + "' not supported!");
			}
		}

		internal byte[] IV
		{
			set
			{
				initVec = value;
			}
		}
	}
}