Mandatory: https://www.schneier.com/blog/archives/2009/09/the_cult_of_s...

But in the introduction to Bruce Schneier's book, Practical Cryptography, he himself says that the world is filled with broken systems built from his earlier book. In fact, he wrote Practical Cryptography in hopes of rectifying the problem.

https://blog.cryptographyengineering.com/2011/11/07/in-defen...

As someone learning crypto (and slowly joining the Cult of Schneier), this is a valuable caution. Thank you!

Applied Cryptography is outdated and made obsolete by Schneier's more recent, Cryptography Engineering. You should just read that instead.

For more information, 'tptacek explains this more succinctly that I could: https://sockpuppet.org/blog/2013/07/22/applied-practical-cry...