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Ask HN: What's the recommended method of adding authentication to a REST API?

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Re: Ask HN: What's the recommended method of adding authentication to a REST API?

#251

Post by ashleycole »

tptacek wrote: post #116

This question comes up all the time on HN. I'm one of a bunch of people on HN that do this kind of work professionally. Here's a recent comment on a recent story about it: https://news.ycombinator.com/item?id=16006394 The short answer is: don't overthink it. Do the simplest thing that will work: use 16+ byte random keys read from /dev/urandom and stored in a database. The cool-kid name for this is "bearer tokens". Yo…

What do you mean when you say: "you do not need to mess around with localStorage"? Aren't you supposed to store this token on the client side (presumably using localStorage/cookies), and then include it in the request?

You seem to know what you're talking about, but i'm a bit confused. With JWT I just store the token in localStorage and then add Authentization Bearer header with the token. What's the recommended approach? To send username + token as part of the form data?

Re: Ask HN: What's the recommended method of adding authentication to a REST API?

#252

Post by yebyen »

riquito wrote: post #246
yebyen wrote: post #156

Earlier quoted context omitted.

It's not a given that something like Diffie-Helman shared secret is going to put the actual secret on the wire during authentication, or that smart auth strategies similar to this one that don't directly transmit secrets are always going to be susceptible to replay attacks. (I am a dog on the internet, so don't listen to me. I also heard that the best way to get a really good answer is not just to ask any old questio…

That's interesting, do you have an example or an article about how it would not be subsceptible to replay attacks?

I think the key is that you must have a shared secret in advance, which is probably something you won't have in most cases unless you're building a point-to-point encryption.

I'm afraid I don't have such an article, and I'm not an expert (just a dog right) but the article that explained Diffie Hellman in a way that made me feel like I was understanding it, you each get a paint color, and you have a pre-negotiated shared secret color. You mix the paint colors to send signals and you know what the colors look like when they are blended with the secret, because you've seen them before.

What's missing from this to make it safe from replay attacks? (It's obvious that if this is the whole setup, if you could observe the color transmitted, you could simply pass the color again if you wanted it to appear that the message was transmitted a second time.)

The answer I think, is a Nonce or IV (Initialization Vector.) I'm not particularly clear on how a nonce is different than an IV or if you would only ever use one or the other, or if you might use both in certain cases, or in all cases...

Re: Ask HN: What's the recommended method of adding authentication to a REST API?

#254

Post by gbruins »

tptacek wrote: post #116

This question comes up all the time on HN. I'm one of a bunch of people on HN that do this kind of work professionally. Here's a recent comment on a recent story about it: https://news.ycombinator.com/item?id=16006394 The short answer is: don't overthink it. Do the simplest thing that will work: use 16+ byte random keys read from /dev/urandom and stored in a database. The cool-kid name for this is "bearer tokens". Yo…

If a web application communicates with it's back end via REST API, and that API is only meant to serve the web app and no other client, and if they communicate with each other on the same origin (http://myapp.com/api), will I need authentication on that REST API at all? Will disabling CORS be good enough?

Sorry if the answer is obvious...this is not my area of expertise.

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