private static CRYPTPROTECT_PROMPTSTRUCT PreparePromptStructure()
{
CRYPTPROTECT_PROMPTSTRUCT cps = new CRYPTPROTECT_PROMPTSTRUCT();
cps.cbSize = Marshal.SizeOf(typeof(CRYPTPROTECT_PROMPTSTRUCT));
cps.dwPromptFlags = 0;
cps.hwndApp = IntPtr.Zero;
cps.szPrompt = null;
return cps;
}
internal extern static bool CryptProtectData(ref DATA_BLOB inputData, string description, ref DATA_BLOB entropy, IntPtr pReserved, ref CRYPTPROTECT_PROMPTSTRUCT promptStruct, UInt32 flags, ref DATA_BLOB outputData);
internal static extern bool CryptUnprotectData(ref DATA_BLOB inputData, IntPtr description, ref DATA_BLOB entropy, IntPtr pReserved, ref CRYPTPROTECT_PROMPTSTRUCT promptStruct, uint flags, ref DATA_BLOB outputData);
//////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////
//////////////////////////////////////////////////////////////////////
private string EncryptText(string clearText)
{
if (clearText == null || clearText.Length < 1)
{
return(clearText);
}
DATA_BLOB inputData, entData, outputData;
SafeNativeMemoryHandle safeInputDataHandle = new SafeNativeMemoryHandle();
SafeNativeMemoryHandle safeOutputDataHandle = new SafeNativeMemoryHandle(true);
SafeNativeMemoryHandle safeEntDataHandle = new SafeNativeMemoryHandle();
inputData.pbData = entData.pbData = outputData.pbData = IntPtr.Zero;
inputData.cbData = entData.cbData = outputData.cbData = 0;
try {
RuntimeHelpers.PrepareConstrainedRegions();
try {
}
finally {
inputData = PrepareDataBlob(clearText);
safeInputDataHandle.SetDataHandle(inputData.pbData);
entData = PrepareDataBlob(_KeyEntropy);
safeEntDataHandle.SetDataHandle(entData.pbData);
}
CRYPTPROTECT_PROMPTSTRUCT prompt = PreparePromptStructure();
UInt32 dwFlags = CRYPTPROTECT_UI_FORBIDDEN;
if (UseMachineProtection)
{
dwFlags |= CRYPTPROTECT_LOCAL_MACHINE;
}
bool success = false;
RuntimeHelpers.PrepareConstrainedRegions();
try {
}
finally {
success = UnsafeNativeMethods.CryptProtectData(ref inputData, "", ref entData,
IntPtr.Zero, ref prompt,
dwFlags, ref outputData);
safeOutputDataHandle.SetDataHandle(outputData.pbData);
}
if (!success || outputData.pbData == IntPtr.Zero)
{
outputData.pbData = IntPtr.Zero;
Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
}
byte[] buf = new byte[outputData.cbData];
Marshal.Copy(outputData.pbData, buf, 0, buf.Length);
return(Convert.ToBase64String(buf));
} finally {
if (!(safeOutputDataHandle == null || safeOutputDataHandle.IsInvalid))
{
safeOutputDataHandle.Dispose();
outputData.pbData = IntPtr.Zero;
}
if (!(safeEntDataHandle == null || safeEntDataHandle.IsInvalid))
{
safeEntDataHandle.Dispose();
entData.pbData = IntPtr.Zero;
}
if (!(safeInputDataHandle == null || safeInputDataHandle.IsInvalid))
{
safeInputDataHandle.Dispose();
inputData.pbData = IntPtr.Zero;
}
}
}
