There were a couple of talks about this at password^12:

Like:

http://passwords12.at.ifi.uio.no/Kirsi_Helkala/

http://passwords12.at.ifi.uio.no/Markus_Duermuth_Password_Se...

But it's a whole conference about passwords... so not sure if I found the presentation I had in mind...:

http://passwords12.at.ifi.uio.no/

And btw, registration is now open for password^16 in Germany in December: https://passwordscon.org/