>It's another way of saying "you'll never really understand this so don't try, just rely on a mysterious cabal of experts".
It's more along the lines of, "you absolutely can understand this if you try, buy trying will take years of your life to learn and apply all attack vectors and their mitigations."
The admonition not to roll your own crypto isn't so that people don't look at crypto. Take a look, fiddle, and hack all you want - just not in production. The saying comes from crypto people noticing avoidable security issues that get created many times people have touched or used crypto code - because even 100% correct crypto code is often also broken in practice.
It's more along the lines of, "you absolutely can understand this if you try, buy trying will take years of your life to learn and apply all attack vectors and their mitigations."
The admonition not to roll your own crypto isn't so that people don't look at crypto. Take a look, fiddle, and hack all you want - just not in production. The saying comes from crypto people noticing avoidable security issues that get created many times people have touched or used crypto code - because even 100% correct crypto code is often also broken in practice.