internal extern static bool CryptGetUserKey(SafeCryptProvHandle hCryptProv, uint pdwKeySpec, ref IntPtr hKey);
public static bool IsPrivateKeyExportable(X509Certificate cert)
{
bool exportable = false;
SafeCryptProvHandle hProvider = null;
IntPtr hKey = IntPtr.Zero;
bool freeProvider = false;
bool freeCryptKey = false;
uint acquireFlags = 0;
uint keySpec = 0;
byte[] permissionBytes = null;
if (CryptAcquireCertificatePrivateKey(cert.Handle, acquireFlags, IntPtr.Zero, out hProvider, ref keySpec, ref freeProvider))
{
SafeGlobalAllocHandle pBytes = SafeGlobalAllocHandle.Empty();
int length = 0;
try {
if (CryptGetUserKey(hProvider, keySpec, ref hKey))
{
freeCryptKey = true;
if (CryptGetKeyParam(hKey, KP_PERMISSIONS, pBytes, ref length, 0))
{
pBytes = new SafeGlobalAllocHandle(length);
if (CryptGetKeyParam(hKey, KP_PERMISSIONS, pBytes, ref length, 0))
{
permissionBytes = new byte[length];
pBytes.Copy(permissionBytes, 0, length);
int cryptNum = BitConverter.ToInt32(permissionBytes, 0);
exportable = ((cryptNum & CRYPT_EXPORT) != 0);
}
}
}
}
finally {
if (freeCryptKey)
{
CryptDestroyKey(hKey);
}
if (freeProvider && hProvider != null)
{
hProvider.Dispose();
hProvider = null;
}
if (pBytes != null)
{
pBytes.Dispose();
pBytes = null;
}
}
}
return(exportable);
}
internal static extern bool CryptAcquireCertificatePrivateKey(IntPtr pCertContext, uint flags, IntPtr reserved, [Out] out SafeCryptProvHandle phCryptProv, ref uint pdwKeySpec, [MarshalAs(UnmanagedType.Bool)] ref bool pfCallerFreeProv);
