C # in ASCII encryption / decryption

#region ========加密======== 

    /// <summary>
    /// 加密
    /// </summary>
    /// <param name="Text"></param>
    /// <returns></returns>
	public static string Encrypt(string Text) 
	{
        return Encrypt(Text, "litianping");
	}
	/// <summary> 
	/// 加密数据 
	/// </summary> 
	/// <param name="Text"></param> 
	/// <param name="sKey"></param> 
	/// <returns></returns> 
	public static string Encrypt(string Text,string sKey) 
	{ 
		DESCryptoServiceProvider des = new DESCryptoServiceProvider(); 
		byte[] inputByteArray; 
		inputByteArray=Encoding.Default.GetBytes(Text); 
		des.Key = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8)); 
		des.IV = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8)); 
		System.IO.MemoryStream ms=new System.IO.MemoryStream(); 
		CryptoStream cs=new CryptoStream(ms,des.CreateEncryptor(),CryptoStreamMode.Write); 
		cs.Write(inputByteArray,0,inputByteArray.Length); 
		cs.FlushFinalBlock(); 
		StringBuilder ret=new StringBuilder(); 
		foreach( byte b in ms.ToArray()) 
		{ 
			ret.AppendFormat("{0:X2}",b); 
		} 
		return ret.ToString(); 
	} 

	#endregion
	
	#region ========解密======== 


    /// <summary>
    /// 解密
    /// </summary>
    /// <param name="Text"></param>
    /// <returns></returns>
	public static string Decrypt(string Text) 
	{
        return Decrypt(Text, "litianping");
	}
	/// <summary> 
	/// 解密数据 
	/// </summary> 
	/// <param name="Text"></param> 
	/// <param name="sKey"></param> 
	/// <returns></returns> 
	public static string Decrypt(string Text,string sKey) 
	{ 
		DESCryptoServiceProvider des = new DESCryptoServiceProvider(); 
		int len; 
		len=Text.Length/2; 
		byte[] inputByteArray = new byte[len]; 
		int x,i; 
		for(x=0;x<len;x++) 
		{ 
			i = Convert.ToInt32(Text.Substring(x * 2, 2), 16); 
			inputByteArray[x]=(byte)i; 
		} 
		des.Key = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8)); 
		des.IV = ASCIIEncoding.ASCII.GetBytes(System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(sKey, "md5").Substring(0, 8)); 
		System.IO.MemoryStream ms=new System.IO.MemoryStream(); 
		CryptoStream cs=new CryptoStream(ms,des.CreateDecryptor(),CryptoStreamMode.Write); 
		cs.Write(inputByteArray,0,inputByteArray.Length); 
		cs.FlushFinalBlock(); 
		return Encoding.Default.GetString(ms.ToArray()); 
	} 

	#endregion