Can I report a cheater in Dark Souls 3?

Yesterday I got invaded by some guy I could not deal any damage to him at all. He didn't even attempt to dodge or block my attacks. I think he could be a cheater.

I understand that due to game mechanics and number of players, it's almost impossible to be invaded by the same player a second time, but I still want him to be punished.

How can I report cheating?

I'm playing on PC from Steam.

You can report a player on Steam.

To do this, open Steam overlay in-game (Shift+Tab by default), click "View Players" in the Friends box.

This will show you all players you've met in Steam games, ordered by time.
If you have already left the game, same list can be accessed from Steam client menu, View -> Players.

From the list, find the suspected cheater and navigate to their profile. You can report the player from there.

Source: Steamcommunity