I worked on a very interesting project about collecting hundreds of millions of public keys and trying to break them: https://research.kudelskisecurity.com/2018/10/16/reaping-and-breaking-keys-at-scale-when-crypto-meets-big-data/

You can see the video of our talk on the topic with my colleague Nils Amiet here: https://www.youtube.com/watch?v=Z7cLRE6t1Q8