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Login with a Public Ed25519 Key

github.com

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Re: Login with a Public Ed25519 Key

#21

Post by pxx »

asojfdowgh wrote: post #17

An easier, more secure approach, would be authviassh://authviassh@auth.server/origin.domain/nonce parsed restrictively authviassh:\/\/authviassh@(${domain_regex})/(${domain_regex})/([0-9a-zA-Z]+) prompting the user: "Would you like to log into origin.domain (via auth.server) using ~/.ssh/your_key?" and then finally running ssh "authviassh@auth.server" -- authviassh "origin.domain" "nonce" with the appropriate additio…

This seems similar in concept to https://github.com/michft/ssh-mars or https://github.com/wes1138/webauth-via-ssh but you could imagine that the person running the SSH server doesn't necessarily need to be the person running the website.

Re: Login with a Public Ed25519 Key

#22

Post by dcow »

I feel like this demo is just a conversation starter and not a serious attempt at a login scheme. Like, signing and verifying using ed25519 is not hard and adding a CLI to do some crypto operations is not novel. If someone was implementing this they wouldn't shell out anyway since there is very good library support in . The only thing WebAuthn needs to figure out is soft keys. Users don't want to enroll devices they want to log in with face/touch ID. The webauthn UX is broken and needs to be revamped so that users can choose a not technically perfect but still effective and better than passwords security posture where they reuse a soft webauthn key across devices. If whatever agent handling the soft key encrypts it at rest using device keys you’re effectively isomorphic to “key never leaves the device”.

It would be nice if hardware devices supported a non-resident key mode where you could give it an encrypted key and it would decrypt the key on device memory using an on-device key and then use the decrypted key for a crypto operation (encryption or signing). Then you could get a pretty much perfectly isomorphic experience with a non-resident key.

Re: Login with a Public Ed25519 Key

#23

Post by inetknght »

dcow wrote: post #22

I feel like this demo is just a conversation starter and not a serious attempt at a login scheme. Like, signing and verifying using ed25519 is not hard and adding a CLI to do some crypto operations is not novel. If someone was implementing this they wouldn't shell out anyway since there is very good library support in . The only thing WebAuthn needs to figure out is soft keys. Users don't want to enroll devices they…

> Users don't want to enroll devices they want to log in with face/touch ID.

Not all users. I'm a user. I want to log in with my SSH key because it's far more secure than my face or fingerprint.

Re: Login with a Public Ed25519 Key

#24

Post by octoberfranklin »

yuliyp wrote: post #13

This feels very broken: - The suggestion of signing the timestamp means that any web site you log into with this can log in as you to any other web site you log in to - Given that there's no namespacing of the signed messages, users can be easily phished into providing a response to a challenge posed by a different web site - It's not obvious what advantages this has over using client cert authentication with TLS, an…

> - The suggestion of signing the timestamp means that any web site you log into with this can log in as you to any other web site you log in to

This is a (privacy) feature, not a bug. It forces you to use a different public key for each website.

Re: Login with a Public Ed25519 Key

#25

Post by dcow »

inetknght wrote: post #23
dcow wrote: post #22

I feel like this demo is just a conversation starter and not a serious attempt at a login scheme. Like, signing and verifying using ed25519 is not hard and adding a CLI to do some crypto operations is not novel. If someone was implementing this they wouldn't shell out anyway since there is very good library support in . The only thing WebAuthn needs to figure out is soft keys. Users don't want to enroll devices they…

> Users don't want to enroll devices they want to log in with face/touch ID. Not all users. I'm a user. I want to log in with my SSH key because it's far more secure than my face or fingerprint.

Yeah sorry I should have qualified: average consumer users.

Re: Login with a Public Ed25519 Key

#26

Post by jazzyjackson »

staticassertion wrote: post #20
jazzyjackson wrote: post #5

Earlier quoted context omitted.

right, would be better for the site to encrypt a one-time-use password with the public key you've, then all you have to do is decrypt it and log in, proving you possess the private key does this have a name? always seemed like the obvious way to do it but I've never implemented auth edit: I guess this is similar to a challenge/sign/verify signature scheme like webauthen, but is it inferior in some way?

SRP, PAKE, and OPAQUE. More generally, zero knowledge proofs (ZKP).

thanks !

Re: Login with a Public Ed25519 Key

#27

Post by [deleted] »

octoberfranklin wrote: post #24
yuliyp wrote: post #13

This feels very broken: - The suggestion of signing the timestamp means that any web site you log into with this can log in as you to any other web site you log in to - Given that there's no namespacing of the signed messages, users can be easily phished into providing a response to a challenge posed by a different web site - It's not obvious what advantages this has over using client cert authentication with TLS, an…

> - The suggestion of signing the timestamp means that any web site you log into with this can log in as you to any other web site you log in to This is a (privacy) feature, not a bug. It forces you to use a different public key for each website.

[deleted]

Re: Login with a Public Ed25519 Key

#28

Post by gruez »

hn_throwaway_99 wrote: post #16
yuliyp wrote: post #13

This feels very broken: - The suggestion of signing the timestamp means that any web site you log into with this can log in as you to any other web site you log in to - Given that there's no namespacing of the signed messages, users can be easily phished into providing a response to a challenge posed by a different web site - It's not obvious what advantages this has over using client cert authentication with TLS, an…

> Given that there's no namespacing of the signed messages, users can be easily phished into providing a response to a challenge posed by a different web site This is key. The whole benefit of hardware token-based authentication is that it is resistant against phishing (because SMS 2-factor and TOTP, e.g. Google Authenticator, are NOT phishing resistant). So this approach is more complicated than those other 2 2FA ap…

>The whole benefit of hardware token-based authentication [...]

Technically it's not something limited to hardware tokens. You can conceivably do something similar with username/password authentication, as long as the credentials are sent to the browser and not the site.

Re: Login with a Public Ed25519 Key

#29

Post by ignoramous »

As many have noted, this scheme is simple only because its only goal is to replace passwords, while seemingly ignoring even common security threats. Reminds me of TripleSec: https://news.ycombinator.com/item?id=9655245

As good as WebAuthn is, research around PAKEs is currently the most exciting to me: https://blog.cloudflare.com/research-directions-in-password-...

Re: Login with a Public Ed25519 Key

#30

Post by woodruffw »

dcow wrote: post #22

I feel like this demo is just a conversation starter and not a serious attempt at a login scheme. Like, signing and verifying using ed25519 is not hard and adding a CLI to do some crypto operations is not novel. If someone was implementing this they wouldn't shell out anyway since there is very good library support in . The only thing WebAuthn needs to figure out is soft keys. Users don't want to enroll devices they…

> Users don't want to enroll devices they want to log in with face/touch ID. The webauthn UX is broken and needs to be revamped so that users can choose a not technically perfect but still effective and better than passwords security posture where they reuse a soft webauthn key across devices.

I'm not sure I understand the problem here. WebAuthn is entirely agnostic about the physical factor: it can be a hardware key, a software implementation, TouchID/FaceID, or anything else. You can already use TouchID and FaceID on sites that use WebAuthn, and the UX is perfectly fine. You still have to enroll the device, but that's no different from the Face/TouchID UX in any other authentication context.

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