I guess this is where I'm getting confused. In some places I see comments which seem to say that "naked hash plus salt" is bad when the salt is the same every time, but possibly not when the salt is different every time. And, of course, in other places I see comments saying that this isn't any good either. And then stuff which has nothing to do with salts or nonces but solely looks at the algorithm (which I don't understand, because even the most up-to-date stuff on attacking popular hashes still seems to be orders of magnitude behind the efficiency of rainbow tables, and rainbow tables don't do as well against a salt that changes with every password).
And, well, this is where I just kinda go off the rails, because it seems as if there's nothing that's ever been conceived by man that doesn't have an article by a security expert saying "what are you, some kind of idiot? Why would anybody use that?"
I don't believe that this topic is, in practice, hard to understand.
You do face the challenge of sorting through all the noise of proposals and retorts --- "what if I use a 64 bit salt?", "what if I use SHA-256 instead of MD5", "what if I use AES to encrypt the passwords", "what if I run SHA1 in Javascript and just exchange the hashes", etc, etc, etc. None of this stuff matters.
The core issue is: your password hash should be cryptographically slow. It should resist account-at-a-time brute force attacks, which are the predominant method used to crack accounts. You can safely ignore the rest of the sideshows.
And finally, I have to say that just because a topic seems annoyingly complex doesn't mean it morally has to be simpler. If security experts are telling you you're an idiot for doing X, by all means get pissed that they called you an idiot, but also stop doing X.
"And finally, I have to say that just because a topic seems annoyingly complex doesn't mean it morally has to be simpler."
I'm OK with complexity. What I'm not OK with is the impression I get that there simply is no option that won't get shouted down. "Making the right choice is complex" is fine when compared to "there is no right choice".
Nobody will shout you down for iterating SHA1 or for using one of the bcrypt/scrypt/PBKDF.
In actual fact, I won't even shout at you for using salted single-pass SHA1, as long as you don't brag about it, or talk about how your "salt" construction improves security.
Well, in an ideal world I'd be in favor of using something better than what we currently have as the default, but for now we have to strike a compromise -- SHA1 is about the "best" hash that's ubiquitously available on the platforms and Python versions we support. Down the road when we've deprecated a couple older Python releases and can rely on things like hashlib being available, it'll be time to talk about improving the default setup.
And, in the context of common use cases, I think it's probably an OK compromise -- I doubt somebody's going to devote the resources to plucking the password for a random blog, for example. Once you need tougher security, you can plug in whatever scheme you like for storing credentials and authenticating users which, anecdotally, most people seem to be doing when warranted (there are quite a few third-party auth backends floating around). And, really, if I were going to brag about anything, it'd probably be the ease with which you can do that -- one class with two methods, a settings tweak and (depending on your credential scheme) possibly a short form class that knows what the incoming data will look like, and you're done. Of course, I think we could make it even easier, so I won't be bragging about it just yet :)
And, well, this is where I just kinda go off the rails, because it seems as if there's nothing that's ever been conceived by man that doesn't have an article by a security expert saying "what are you, some kind of idiot? Why would anybody use that?"