Tpm2Lib.AuthSession.GetAuthHmac C# (CSharp) Method

        internal byte[] GetAuthHmac(byte[] parmHash, Direction direction, byte[] nonceDec = null, byte[] nonceEnc = null)
        {
            // special case.  If this is a policy session and the session includes PolicyPassword the 
            // TPM expects and assumes that the HMAC field will have the plaintext entity field as in 
            // a PWAP session (the related PolicyAuthValue demands an HMAC as usual)
            if (PlaintextAuth)
            {
                return Handle.Auth ?? AuthHandle.Auth;
            }

            byte[] nonceNewer, nonceOlder;
            if (direction == Direction.Command)
            {
                nonceNewer = NonceCaller;
                nonceOlder = NonceTpm;
            }
            else
            {
                nonceNewer = NonceTpm;
                nonceOlder = NonceCaller;
            }
            byte[] sessionAttrs = Marshaller.GetTpmRepresentation(Attrs);

            byte[] auth = Handle.Auth;
            if (AuthHandle != null && Handle != TpmRh.TpmRsPw && auth == null &&
                ((SessionType != TpmSe.Policy && BindObject != AuthHandle) ||
                 (SessionType == TpmSe.Policy && SessIncludesAuth)))
            {
                auth = Globs.TrimTrailingZeros(AuthHandle.Auth);
            }
            byte[] hmacKey = Globs.Concatenate(SessionKey, auth);
            byte[] bufToHmac = Globs.Concatenate(new[] {parmHash, nonceNewer, nonceOlder,
                                                        nonceDec, nonceEnc, sessionAttrs});

            byte[] hmac = CryptoLib.HmacData(AuthHash, hmacKey, bufToHmac);
#if false
            Console.WriteLine(Globs.FormatBytesCompact("hmacKey: ", hmacKey));
            Console.WriteLine(Globs.FormatBytesCompact("nonceNewer: ", nonceNewer));
            Console.WriteLine(Globs.FormatBytesCompact("nonceOlder: ", nonceOlder));
            Console.WriteLine(Globs.FormatBytesCompact("nonceDec: ", nonceDec));
            Console.WriteLine(Globs.FormatBytesCompact("nonceEnc: ", nonceEnc));
            Console.WriteLine(Globs.FormatBytesCompact("attrs: ", sessionAttrs));
            Console.WriteLine(Globs.FormatBytesCompact("HMAC: ", hmac));
#endif
            return hmac;
        }