It does say at the top "originally written in 1998" and it was basically amended over time, but regardless I still love learning about "historical" views.

Example: A textbook from '95 had a pretty large section on "the future" of ECC and "current" trends in research. It was interesting seeing what came true, or what was still being worked on.

Indeed. Interesting mix of theory ("here's how RSA works and why") and practice (list of specs and RFCs), but very old-school.

Today, I'd expect less focus on RSA and PGP, and instead a mention of elliptic curves, the Signal protocol (double ratchet), etc.