While the fundamentals are always relevant, IIRC this book has been dated even 10 years ago, when Schneier's Cryptography Engineering was already recommended instead if you wanted practical advice.
For a more theoretically backed approach Dan Boneh's book ( https://toc.cryptobook.us/ ) is a very good resource.
For a more theoretically backed approach Dan Boneh's book ( https://toc.cryptobook.us/ ) is a very good resource.