Address DEC issue with auth tag not being generated for GCM mode for empty data cases and streaming methods.

Author: denovosoftware

Source/DECCipherFormats.pas

@@ -738,6 +738,7 @@ procedure TDECFormattedCipher.DoEncodeDecodeStream(const Source, Dest: TStream;
   StartPos := Pos;
 
   if DataSize > 0 then
+  begin
     try
       if Assigned(OnProgress) then
         OnProgress(Max, 0, Started);
@@ -781,6 +782,13 @@ procedure TDECFormattedCipher.DoEncodeDecodeStream(const Source, Dest: TStream;
       if Assigned(OnProgress) then
         OnProgress(Max, Max, Finished);
     end;
+  end
+  else
+    if (FMode = cmGCM) then
+    begin
+      Buffer := nil;
+      CipherProc(Buffer, Buffer, 0);
+    end;
 end;
 
 procedure TDECFormattedCipher.EncodeStream(const Source, Dest: TStream; DataSize: Int64;

Unit Tests/Tests/TestDECCipherModesGCM.pas

@@ -654,10 +654,6 @@ procedure TestTDECGCM.TestDecodeStream;
     begin
       ctBytes := TFormat_HexL.Decode(BytesOf(TestDataSet.TestData[i].CT));
 
-      // FIXME: Auth tag does not generate for empty CT
-      if Length(ctBytes) = 0 then
-        continue;
-
       try
 
 
@@ -735,10 +731,6 @@ procedure TestTDECGCM.TestEncodeStream;
     begin
       ptBytes := TFormat_HexL.Decode(BytesOf(TestDataSet.TestData[i].PT));
 
-      // FIXME: Auth tag does not generate for empty PT
-      if Length(ptBytes) = 0 then
-        continue;
-
       FCipherAES.Init(BytesOf(TFormat_HexL.Decode(TestDataSet.TestData[i].CryptKey)),
                       BytesOf(TFormat_HexL.Decode(TestDataSet.TestData[i].InitVector)),
                       $FF);