They sell via BMTMicro, who have been doing this stuff for a great many years. Don't worry about security.
Dark Souls is the sixth main game in the King's Field series. It's not like they suddenly came up with this 'dark dungeon-crawl' thing two years ago. They've been at it since the 90s.
Unfortunately, while DX11 support is nice, this patch also inexplicably removes some previously-supported screen resolutions, including the (perfectly valid, and native on many screens) 1360 x 768, which is a standard 16:9 format.
I now have to run the game at 1280 x 720, upscaled to my monitor.