In the fraud case at tech company NS8[1] (for which the CEO was recently sentenced to prison), the CEO apparently edited PDF bank statements before sharing them with his CFO. I think most people naturally assume that a PDF is unalterable so a PDF document. While not commonly exploited, that assumption is a big security gap. We need a way to sign PDFs to ensure their authenticity.

[1]https://www.sec.gov/litigation/complaints/2020/comp24905.pdf