How is this helpful? How does it help to point out that so many of the people who are deploying crypto are so boned that their systems are compromised before the crypto even comes into play? Help me understand this. If you can't get the basic systems programming concerns of your software right, what business does your system have telling users that it's "cryptographically secured"?
First: I agree with all of your practical advice. I'm making a meta point to security people like you and the author of the linked post.
And I'm not sure it's "helpful" really . It's more musing on whether or not this kind of advice is hurting more than helping. What you are saying amounts to "Crypto is really hard so use expert-authored solutions." But in my experience what people hear is "Crypto is Hugely Important and I'm using a expert-authored solution and using the same jargon, so you need to listen to me about all that security stuff and do what I say even though it's totally impractical."
Broadly, I guess I'm thinking that this creates little BOfH monsters, where a more nuanced, "big picture" frame might engender more thought about costs and tradeoffs.
I would not have written the same post Tony wrote.
Generally: I'm comfortable writing about crypto when the subject is "how you would practically break a system that makes mistake X or mistake Y". I'm not comfortable about posts with prescriptive content.
I am also not comfortable with posts that condone building cryptosystems out of primitives, even when they limit the solution space to well-regarded tuples of those primitives. If I had to write a prescriptive post about crypto, it would state clearly: you cannot DIY this, and you must use a vetted cryptosystem; your choices include NACL, Keyczar, and PGP.
