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Passkeys and Modern Authentication

(lucumr.pocoo.org)
184 points Bogdanp | 4 comments | 02 Sep 25 13:47 UTC | HN request time: 0.001s | source
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alphazard ◴[02 Sep 25 17:11 UTC] No.45105959[source]▶
Unfortunately the tech community is full of people who pride themselves on being aware of and advocating for the latest standard put out by whatever company. That's how we end up with lots of complicated nonsense like most of what is sent in HTTP headers, or the contents of a TLS certificate.

On the topic of authentication, it's solved. SSH nailed it, any further complexity is strictly worse. Signing up is uploading a public key. Signing in is cryptographically signing a commitment to the current ephemeral tunnel.

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01HNNWZ0MV43FF ◴[02 Sep 25 17:28 UTC] No.45106261[source]▶
> Signing up is uploading a public key. Signing in is cryptographically signing a commitment to the current ephemeral tunnel.

How do I sign in from multiple computers?

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alphazard ◴[02 Sep 25 17:35 UTC] No.45106359[source]▶
There are multiple solutions to this, with tradeoffs. Doesn't change the fact that the service should only want a public key, and you should only give the service a public key. That's where this new complexity is being forced on users and developers. You need to be able to sign in, or let your users sign in, but you can choose how complicated of a key management strategy to have.

You can either have 1 key pair per service and sync them with something like 1password. Or you can have 1 key per service per device. Keys that never leave the device is usually considered more secure (and I agree for what I consider my threat model to be).

Important services like primary email, your bank, or cloud platform should probably do 1 key per device. Everything else benefits from the simplicity of 1 key per service with the keys synced.

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1. tadfisher ◴[02 Sep 25 17:47 UTC] No.45106555[source]▶
You are describing passkeys. All of this applies to the passkey scheme.

Actually, a benefit of passkeys is the standardization of client-side cross-device authz operations via caBLE and similar; your secret keys never leave your primary device, but are usable from other devices over a variety of transports.

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2. alphazard ◴[02 Sep 25 17:59 UTC] No.45106724[source]▶
> All of this applies to the passkey scheme.

It also applies to SSH keys. I never said that passkeys couldn't do everything SSH keys can do. My criticism is that they are more complicated to do the same thing.

This is exactly what not valuing simplicity looks like.

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3. palata ◴[02 Sep 25 20:48 UTC] No.45108832[source]▶
A passkey uses FIDO2, which asks you to sign a challenge. If you use OpenSSH with a security key, it will... use FIDO2. If you use OpenSSH with a private key on your computer, you also sign a challenge, right? So it's not less complicated.

WebAuthn just adds a few things like the relying party and a counter (that nobody seems to use). And the relying party helps preventing phishing, which SSH doesn't do really well in practice (most people don't use SSH certificates and don't check the server fingerprints).

So it's just not true that passkeys are more complicated to do the same thing.

4. NoGravitas ◴[03 Sep 25 16:14 UTC] No.45117505[source]▶
Except that passkeys also add other things, like attestation, relying parties, and restrictions on how keys are synced, and so on. I don't think anyone disagrees that the basic idea of "we should be using site-specific public/private keypairs for logins" is good.