private string DecryptText(string encText)
{
DATA_BLOB data_blob;
DATA_BLOB data_blob2;
DATA_BLOB data_blob3;
string str;
if ((encText == null) || (encText.Length < 1))
{
return encText;
}
SafeNativeMemoryHandle handle = new SafeNativeMemoryHandle();
SafeNativeMemoryHandle handle2 = new SafeNativeMemoryHandle(true);
SafeNativeMemoryHandle handle3 = new SafeNativeMemoryHandle();
data_blob.pbData = data_blob2.pbData = data_blob3.pbData = IntPtr.Zero;
data_blob.cbData = data_blob2.cbData = data_blob3.cbData = 0;
try
{
RuntimeHelpers.PrepareConstrainedRegions();
try
{
}
finally
{
data_blob = PrepareDataBlob(Convert.FromBase64String(encText));
handle.SetDataHandle(data_blob.pbData);
data_blob2 = PrepareDataBlob(this._KeyEntropy);
handle3.SetDataHandle(data_blob2.pbData);
}
CRYPTPROTECT_PROMPTSTRUCT promptStruct = PreparePromptStructure();
uint flags = 1;
if (this.UseMachineProtection)
{
flags |= 4;
}
bool flag = false;
RuntimeHelpers.PrepareConstrainedRegions();
try
{
}
finally
{
flag = Microsoft.Win32.UnsafeNativeMethods.CryptUnprotectData(ref data_blob, IntPtr.Zero, ref data_blob2, IntPtr.Zero, ref promptStruct, flags, ref data_blob3);
handle2.SetDataHandle(data_blob3.pbData);
}
if (!flag || (data_blob3.pbData == IntPtr.Zero))
{
data_blob3.pbData = IntPtr.Zero;
Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
}
byte[] destination = new byte[data_blob3.cbData];
Marshal.Copy(data_blob3.pbData, destination, 0, destination.Length);
str = Encoding.Unicode.GetString(destination);
}
finally
{
if ((handle2 != null) && !handle2.IsInvalid)
{
handle2.Dispose();
data_blob3.pbData = IntPtr.Zero;
}
if ((handle3 != null) && !handle3.IsInvalid)
{
handle3.Dispose();
data_blob2.pbData = IntPtr.Zero;
}
if ((handle != null) && !handle.IsInvalid)
{
handle.Dispose();
data_blob.pbData = IntPtr.Zero;
}
}
return str;
}