internal static string QueryContextAuthenticationPackage(SafeDeleteContext securityContext)
        {
            SecPkgContext_NegotiationInfoW ctx = default;
            bool success = SSPIWrapper.QueryBlittableContextAttributes(GlobalSSPI.SSPIAuth, securityContext, Interop.SspiCli.ContextAttribute.SECPKG_ATTR_NEGOTIATION_INFO, typeof(SafeFreeContextBuffer), out SafeHandle sspiHandle, ref ctx);

            using (sspiHandle)
            {
                return(success ? NegotiationInfoClass.GetAuthenticationPackageName(sspiHandle, (int)ctx.NegotiationState) : null);
            }
        }
        public static unsafe object QueryContextAttributes(
            SafeDeleteContext securityContext,
            ContextAttribute contextAttribute)
        {
            int nativeBlockSize = IntPtr.Size;
            Type handleType = null;

            switch (contextAttribute)
            {
                case ContextAttribute.Flags:
                    break;
                case ContextAttribute.Sizes:
                    nativeBlockSize = SecSizes.SizeOf;
                    break;
                case ContextAttribute.StreamSizes:
                    nativeBlockSize = StreamSizes.SizeOf;
                    break;
                case ContextAttribute.Names:
                    handleType = typeof(SafeFreeContextBuffer);
                    break;
                case ContextAttribute.PackageInfo:
                    handleType = typeof(SafeFreeContextBuffer);
                    break;
                case ContextAttribute.NegotiationInfo:
                    handleType = typeof(SafeFreeContextBuffer);
                    nativeBlockSize = Marshal.SizeOf(typeof(NegotiationInfo));
                    break;
                case ContextAttribute.RemoteCertificate:
                    handleType = typeof(SafeFreeCertContext);
                    break;
                case ContextAttribute.LocalCertificate:
                    handleType = typeof(SafeFreeCertContext);
                    break;
                case ContextAttribute.ConnectionInfo:
                    nativeBlockSize = Marshal.SizeOf(typeof(SslConnectionInfo));
                    break;
                case ContextAttribute.Lifespan:
                    nativeBlockSize = LifeSpan_Struct.Size;
                    break;
                case ContextAttribute.SessionKey:
                    handleType = typeof(SafeFreeContextBuffer);
                    nativeBlockSize = SecPkgContext_SessionKey.Size;
                    break;
                default:
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new InvalidEnumArgumentException("contextAttribute", (int)contextAttribute,
                    typeof(ContextAttribute)));
            }

            SafeHandle sspiHandle = null;
            object attribute = null;
            try
            {
                byte[] nativeBuffer = new byte[nativeBlockSize];
                int errorCode = QueryContextAttributes(securityContext, contextAttribute, nativeBuffer, handleType, out sspiHandle);
                if (errorCode != 0)
                {
                    throw DiagnosticUtility.ExceptionUtility.ThrowHelperError(new Win32Exception(errorCode));
                }

                switch (contextAttribute)
                {
                    case ContextAttribute.Flags:
                        fixed (byte* pnativeBuffer = nativeBuffer)
                        {
                            attribute = (object)Marshal.ReadInt32(new IntPtr(pnativeBuffer));
                        }
                        break;
                    case ContextAttribute.Sizes:
                        attribute = new SecSizes(nativeBuffer);
                        break;
                    case ContextAttribute.StreamSizes:
                        attribute = new StreamSizes(nativeBuffer);
                        break;
                    case ContextAttribute.Names:
                        attribute = Marshal.PtrToStringUni(sspiHandle.DangerousGetHandle());
                        break;
                    case ContextAttribute.PackageInfo:
                        attribute = new SecurityPackageInfoClass(sspiHandle, 0);
                        break;
                    case ContextAttribute.NegotiationInfo:
                        unsafe
                        {
                            fixed (void* ptr = nativeBuffer)
                            {
                                attribute = new NegotiationInfoClass(sspiHandle, Marshal.ReadInt32(new IntPtr(ptr), NegotiationInfo.NegotiationStateOffset));
                            }
                        }
                        break;
                    case ContextAttribute.LocalCertificate:
                        goto case ContextAttribute.RemoteCertificate;
                    case ContextAttribute.RemoteCertificate:
                        attribute = sspiHandle;
                        sspiHandle = null;
                        break;
                    case ContextAttribute.ConnectionInfo:
                        attribute = new SslConnectionInfo(nativeBuffer);
                        break;
                    case ContextAttribute.Lifespan:
                        attribute = new LifeSpan(nativeBuffer);
                        break;
                    case ContextAttribute.SessionKey:
                        unsafe
                        {
                            fixed (void* ptr = nativeBuffer)
                            {
                                attribute = new SecuritySessionKeyClass(sspiHandle, Marshal.ReadInt32(new IntPtr(ptr)));
                            }
                        }
                        break;
                    default:
                        // will return null
                        break;
                }
            }
            finally
            {
                if (sspiHandle != null)
                {
                    sspiHandle.Close();
                }
            }
            return attribute;
        }