Ask HN: Socratic dialogue between two cybersecurity experts?

I cannot for the life of me find this fantastic resource I saw posted on HN a while ago.

It was a fake conversation between Alice and Bob, where they took turns explaining how Alice would protect a password submission form, and then how Bob would thwart the protection, and how Alice would protect it again, and so on.

No keywords are working so I may be mis-remembering some aspects of it.