在.net 4.5下FormsAuthentication.HashPasswordForStoringInConfigFile过时的问题

源码如下：

#region ========加密========

/// <summary>
/// 加密
/// </summary>
/// <param name="Text"></param>
/// <returns></returns>
public static string Encrypt(string Text)
{
if (Text.Trim() == "")
return "";
else
return Encrypt(Text, "passkey");
}
/// <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)
{
if (Text.Trim() == "")
return "";
else
return Decrypt(Text, "passkey");
}
/// <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

升级到4.5后  的代码（对不对 不知道 也是复制别人的，但是我测试是没问题的，原理我也不清楚。）：

#region ========加密========

/// <summary>
/// 加密
/// </summary>
/// <param name="Text"></param>
/// <returns></returns>
public static string Encrypt(string Text)
{
if (Text.Trim() == "")
return "";
else
return Encrypt(Text, "passkey");
}
/// <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(MD5(sKey).Substring(0, 8));
des.IV = ASCIIEncoding.ASCII.GetBytes(MD5(sKey).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)
{
if (Text.Trim() == "")
return "";
else
return Decrypt(Text, "passkey");
}
/// <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(MD5(sKey).Substring(0, 8));
des.IV = ASCIIEncoding.ASCII.GetBytes(MD5(sKey).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());
}

public static string MD5(string str)
{
//微软md5方法参考return FormsAuthentication.HashPasswordForStoringInConfigFile(str, "md5");
byte[] b = Encoding.Default.GetBytes(str);
b = new MD5CryptoServiceProvider().ComputeHash(b);
string ret = "";
for (int i = 0; i < b.Length; i++)
ret += b[i].ToString("X").PadLeft(2, '0');
return ret;
}

#endregion