System.Net.SecurityStatusAdapterPal.GetSecurityStatusPalFromInterop C# (CSharp) Method

        internal static SecurityStatusPal GetSecurityStatusPalFromInterop(Interop.SECURITY_STATUS win32SecurityStatus, bool attachException = false)
        {
            SecurityStatusPalErrorCode statusCode;

            if (!s_statusDictionary.TryGetForward(win32SecurityStatus, out statusCode))
            {
                Debug.Fail("Unknown Interop.SecurityStatus value: " + win32SecurityStatus);
                throw new InternalException();
            }

            if (attachException)
            {
                return new SecurityStatusPal(statusCode, new Win32Exception((int)win32SecurityStatus));
            }
            else
            {
                return new SecurityStatusPal(statusCode);
            }
        }

        public static SecurityStatusPal DecryptMessage(SafeDeleteContext securityContext, byte[] buffer, ref int offset, ref int count)
        {
            // Decryption using SCHANNEL requires four buffers.
            SecurityBuffer[] decspc = new SecurityBuffer[4];
            decspc[0] = new SecurityBuffer(buffer, offset, count, SecurityBufferType.Data);
            decspc[1] = new SecurityBuffer(null, SecurityBufferType.Empty);
            decspc[2] = new SecurityBuffer(null, SecurityBufferType.Empty);
            decspc[3] = new SecurityBuffer(null, SecurityBufferType.Empty);

            Interop.SecurityStatus errorCode = (Interop.SecurityStatus)SSPIWrapper.DecryptMessage(
                GlobalSSPI.SSPISecureChannel,
                securityContext,
                decspc,
                0);

            count = 0;
            for (int i = 0; i < decspc.Length; i++)
            {
                // Successfully decoded data and placed it at the following position in the buffer,
                if ((errorCode == Interop.SecurityStatus.OK && decspc[i].type == SecurityBufferType.Data)
                    // or we failed to decode the data, here is the encoded data.
                    || (errorCode != Interop.SecurityStatus.OK && decspc[i].type == SecurityBufferType.Extra))
                {
                    offset = decspc[i].offset;
                    count  = decspc[i].size;
                    break;
                }
            }

            return(SecurityStatusAdapterPal.GetSecurityStatusPalFromInterop(errorCode));
        }