Login with a Public Ed25519 Key
github.com
github.com
- 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, and it has many downsides.
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 approaches but with no additional security benefit.
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.
What’s broken here is not that user agents are or aren’t validating the origin (or relying party)—it’s that the same key+challenge is used for every origin. (As a result, there’s nothing for the user agent to validate, because the same signature is used for all origins!)
It’s like using the same password for every website you log into. As severe understatement, this is a very, very bad protocol design, and nobody should use it.
This is a (privacy) feature, not a bug. It forces you to use a different public key for each website.
Anyway, unclear to me how this is better than x509 client certs, except that the author probably doesn't know about them.
FIDO is the banking world's version of the Intel Management Engine and HDCP.
https://fidoalliance.org/specs/FDO/FIDO-Device-Onboard-RD-v1...
In my experience, the vast majority of (consumer) RPs do not require specific batch attestation, which is why you can make your own FIDO key: https://github.com/google/OpenSK.
I am under the impression support for attestation was controversial in FIDO--it's clearly useful for enterprise scenarios (e.g. where an enterprise requires some silly certification like FIPS: https://support.yubico.com/hc/en-us/articles/360016614760-Ac...), but there's always the risk that consumer-facing RPs require it for no good reason.
My employer requires FIPS certification due to FedRAMP; I'd be interested in how you would propose to change FIDO such that--as now--I can use a single key for work and for all my consumer needs while eliminating attestation. (One obvious option is for my employer to issue already-enrolled keys and disallow self-enrollment, but that has other headaches...)
The point is that it takes that choice out of the users' hands.
Choosing which manufacturer's hardware to use, or even to make their own, is the user's choice to make.
> use a single key for work and for all my consumer needs
You shouldn't. That's like expecting to be able to use your work laptop for personal stuff.
Unclear to me why you think the user--and not the IdP--should have the final say here.
> You shouldn't. That's like expecting to be able to use your work laptop for personal stuff.
Except FIDO identities are unlinkable even if using the same hardware.
I understand for a corporate setup employees are threat vectors. But that depressing outlook isn't how most people view the consumer space. We want: consumer x signed this auth challenge. We do not want: authority Y said consumer X signed this auth challenge. That’s just CA SSO style oligarchy repeated.
Why wouldn't you trust the consumer and their preferred authentication agent to participate in an authentication challenge? Consumer apps don’t need to ensure that consumers are using a hardware token device they just need to arrange an authentication dance that doesn't involve a shared secret.
But like I said, most consumer IdPs aren’t doing attestation checks, and it’s discouraged, so I think you’re making a big deal of it. :)
If a bank feels the need to control the hardware I use, they must provide that hardware. Their needs absolutely do not entitle them to impose codesigning/bootloader-locking requirements on my other devices, such as my phone or my laptop.
> aren’t doing attestation checks, and it’s discouraged
That will change. If it weren't, they wouldn't have bothered putting it into the spec. Or they could have used symmetric cryptography for attestation, like the bank-issued token cards and the chip in your chip-and-PIN card do.
And the reason I can do that is because my work cares that I use a FIPS compliant key, but nobody else does—because consumer RPs don’t do this.
Have you encountered any consumer RP enforcing attestation? Or is this concern of yours totally speculative?
I don’t know what this Bank of America card you refer to is, but presumably it was phishable auth, since it had an LCD key? Without a standard supported by user-agents, I don’t know how someone would enforce an out-of-band/unphishable auth mechanism like FIDO+Webauthn on their own, but I’m curious to hear you explain it!
Even Microsoft's half-arsed explanation of how this works inside Azure AD says you should probably not use it.
And I tell Firefox "No" when it asks me during enrollment if the site is allowed attestation from my devices, there are no public sites I've used where this was rejected as unacceptable, that includes GitHub, Google's sites, Facebook, and Login.gov.
Signatures are only valid for about 30 - 60 seconds (depending on the server config) and may not be re-used after a successful login. Try to create a key pair and log into the test website. Then try to use the same signature to do so again.
It's not meant for federation, single-sign on (which is single compromise IMPO) or anything that is commonly discussed in the security community. It's foreign to most (I understand that), and I just wanted to share it and start a discussion.
My comment has nothing to do with federation or SSO, so I'm not sure why you mentioned those?
These signatures are meant to be used to authenticate to a website. If multiple websites implement this idea, then end users should have multiple key pairs (one for each site). So there would be no way a signature for one site could be misused or abused on another.
I believe the github site and the demo website do describe the problem and goals. Webauthn is too complex. Passwords are bad. Hashes are dumped from databases and cracked. Passwords are stuffed, etc. The complexity of webauthn is not the answer.
In this scheme, the website only knows its users' public Ed25519 keys. These keys are harmless and it does not matter if they are stolen (they cannot be used to cause any harm).
The users are in full control of the keys. There is no CA signing TLS certs, etc. The web service and its users are in full control of the process and they are using open-source software. Full transparency that is easily understood by all parties.
Also, there is no identifying information in an Ed25519 key. One goal I have is user anonymity. This scheme allows for that too. No email, phone, etc. Just a public Ed25519 key fully controlled by its end user.
> Because it was in reply to my earlier comment saying this is not SSO.
The person you were replying to was also not talking about SSO, which makes me think you don't understand that (valid, and fundamental) criticism of your proposal. :-/
> Webauthn is too complex.
Which functionality would you remove, and what tradeoffs does that get you?
> Passwords are bad. Hashes are dumped from databases and cracked.
Surely it's easier for an IdP to use scrypt with some meaningful salt than to implement this fully novel and unsupported scheme.
> Passwords are stuffed, etc.
These seem like problems that affect password reuse. According to your design, users should just know better than to reuse keys, so...why not just know better than to reuse passwords?
> There is no CA signing TLS certs, etc.
So why not use self-signed X509 client certs instead? This is actually a thing browsers actually support.
> The web service and its users are in full control of the process and they are using open-source software.
This is a category error. We were discussing a protocol. If you think your specific implementation of that protocol is better than all the open source implementations of FIDO+WebAuthn, X509 client certs, PAKE, etc...well, you're probably wrong. :)
> One goal I have is user anonymity.
You have not explained how your system is more anonymous than the existing, well-defined, standards-compliant alternatives.
Edit: Just to be clear about the tone of my feedback: my intention is to help you understand the context in which you are making your proposal and, ideally, understand the design tradeoffs existing systems have made. I know it's easy to become attached to an idea and take criticism like a personal attack. I hope you can take this constructively.
Honestly, this discussion isn’t worth the time.
As for software webauthn keys:
- What do you mean “locked up in browser land?” You can use FIDO elsewhere (e.g. ssh https://ubuntu.com/blog/enhanced-ssh-and-fido-authentication...).
- Softkeys are available—in fact, iOS, Android, MacOS, and Windows 11 all do webauthn by default, without the need for a hardware token.
> Honestly, this discussion isn’t worth the time.
That’s my point. If it’s not worth your time then let others who are interested discuss rather than just pissing all over the author’s project.
> - Softkeys are available—in fact, iOS, Android, MacOS, and Windows 11 all do webauthn by default, without the need for a hardware token.
That’s not soft keys it’s “platform authenticator”.
When I say softkeys I mean keys managed by a user agent such that they can be portable, like is common with ssh. SSH is popular because it’s gives users the freedom to easily elect their security posture: do they want a user key that can be deployed to different devices or are they super paranoid and want a device key. Do they want a software agent to manage soft keys for them and it can handle the device security and hardware crypto engine support. Not your concern, not the protocols concern, not the services concern: it’s the user’s concern.
Wireguard has soft keys, too.
WebAuthn’s crowd and browser implementers on the other hand seem fixated on making sure users never have the option to deploy the protocol in such a way. That’s the problem.
I don't know of a VPN that uses PAKE, so I don't get this comparison, but whatever.
My point about certs was that OP was effectively proposing self-signed X509 client certs. It's unclear to me in what way those are harder to use than the proposal here, except that they actually are a widely accepted standard with user agent support.
> WebAuthn’s crowd and browser implementers on the other hand seem fixated on making sure users never have the option to deploy the protocol in such a way. That’s the problem.
https://github.com/herrjemand/awesome-webauthn#software-auth...?
You are correct that client certs have user agent support. Honestly it’s a pretty poor UX though. Have you actually tried building a consumer application that uses client certs in the browser? Good luck getting users to install client certs. Client certs work fine everywhere else where you can run bespoke client software (native apps) except for the part where they authenticate the connection and not the request, but that’s not the point either.
Anyway it’s great that other implementations of webauthn exist. But like I just said for client certs: outside of the browser anyone can do anything so webauthn is not a game changer there (not to downplay it). Where WebAuthn matters is for client authentication in the browser and in that arena it is locked down to platform auth and hardware device auth mechanisms. There is no way users could benefit from webauthn right now without the browser-supplied UX.
All I’m saying is that WebAuthn would be way more viable in the way people are asking for in this thread if for example browsers/platforms allowed extensions to participate as a soft WebAuthn agent so that users could choose their preferred WebAuthn backend and UX instead of the browser supplied options. The browser client cert UX sucks and so does browser vendor WebAuthn and I think their adoption story is all the proof you need.
I personally would like reusable keys, and I agree namespace or some other mechanism is needed.
I generally prefer to link my identity among websites and I'm generally not concerned about anonymity or privacy. "A key for each website" is nearly worthless to me.
The ability of others to spoof my identity because a website uses passwords, and most websites provide little to no logging, let alone a standardization, infuriates me. That is a outsized use case I see little attention given to.
If I tweet, users are forced to trust Twitter's authentication system that I tweeted. I don't trust Twitter's authentication systems.
Public key authentication permits third parties to verify my actions without the need to trust system authentication systems.
"Private keys never leave end users' devices" How does it guarantee that, considering it saves the private key in the file system? It can be trivially copied off device from there.
The examples also appear to encourage key reuse, and since the challenge is the current time, the signed auth message can be replayed against any other site where the user set up using the same key.
Webauthn doesn't require separate keys per site and user vigilance to stay secure, because it has a-not-so-simple challenge-response protocol that is site-specific. For end users Webauthn is easier to use: just press a foolproof button.
I don't want to sound too negative. ed25519 keys are neat, and have fun implementing software using them. Let's just be realistic that a practical cryptographic system needs many more features, and Webauthn has them for a reason.
A few seconds is plenty of time for an automated system to cause harm.
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?
I feel like I knew that already. ;)
The advantage is that your private key can't be leaked on a third party website.
As it stands, anyone who has access to a private key momentarily can generate any number of tokens for use, practically indefinitely (just sign a timestamp for every second for the next N years). This system is open to replay attacks as well.
It also glosses over the entire problem of trust establishment, cert revocation, etc.
Since it is akin to device not user authentication, the keypair may be copied between machines and suffer the intricacies of the details used to do so, weakening the keypair FOR ITS ENTIRE FUTURE LIFETIME. Replay attacks are trivial to perform.
It's a nice idea that is well explored elsewhere, but this should not even be considered an implementation of how to login into a system. This is not user authentication, even ignoring its flaws. This is auth for the device on which the keypair resides. Crypto is easy to get wrong even for experts.
The inclusion of a nonce/challenge (and other chosen-text and offline-attack mitigations) helps with a lot of security flaws, and that you've omitted them for no clear reason undermines your position as creator of a novel protocol.
As a trivial example, imagine that someone else comes up with a protocol that uses a signed current-date to authorise a bank transfer; as it's not distinguishable from your protocol, there would be many avenues for tricking a user into providing you with the ability to steal their money.
In responses elsewhere in the thread, you say that users should have a public key per website, but in your readme, you repeatedly imply that users have a single key-pair. "Register your base64 encoded public Ed25519 key with the website." "Use your private Ed25519 key to sign the current Unix Epoch Time" "Websites store the users' public keys."
Requiring users to keep generating keys and manage them manually introduces insecurity through non-compliance. It's not simple if you've got to manage something that behaves entirely like a local password database.
You say elsewhere "The demo website and the github repo contain this information" - but the demo website has no descriptive text (can you perhaps provide a link?) and the readme barely mentions threat models or goals. How do you prevent MitM attacks? Can your design support multi-party authentication or delegation of any kind?
I have no experience with WebAuthn, but it's likely that a lot of its features are to improve security in many ways, and omitting these features might make things easier at request-protocol level, but perhaps just simplistic overall.
You say you're trying to facilitate a conversation, but the proposal is so basic that you're effectively asking people to create a useful protocol for you.
Relying on google auth is too risky as google can just pull the carpet on any user. I do like a key management type solution with a backup factor like maybe emails and phones (2 of N kinda thing) if keys get lost. Google Authenticator (ironically!) would be a cool way to do it and keep sites siloed while using the same mechanism to log into each of them.
For many things a “scan this qr on your phone to log in” type mechanism linked to a key management app that calls an endpoint would be ideal - we tend to keep our phones working, charged and functioning in these post pandemic days. In Australia you can have your vax, covid check in, driving license, credit card of course, and various government vouchers all on the phone.
As much as I hate that for various 1984ish reasons, Im glad iPhone exists and is privacy centric, fairly robust and secure and with something like GA I feel quite safe logging into most sites that kind of way. Guess I am spoilt that an iPhone isn’t financially a stretch, i hope key chain type devices can be sold for $1 and stuck on your keyring with 12 words in a safe place for those who cant afford this luxury. I have’t looked into it.
I could then share authentication for certain things like say amazon prime with trusted people. There is this middle ground between individual and corporate (families/startups/friendship groups) that would be catered for here.
Tldr; passwords suck!
In many regards, this scheme is no better than a strong password in terms of guarantees provided. In terms of UX, it's strictly worse than a password (and those are already pretty bad!) It's not a second factor at all, and thus isn't really an "alternative" to WebAuthn.
However, if you do this, you rapidly start to discover some of the reasons behind WebAuthn's design choices. For example, to prevent phishing/replay/linkage, the "authenticator" (the thing managing the keys) has to know the origin/RP. And to allow hardware and software authenticators, you need some protocol like CTAP to abstract that out. And because some RPs want to require hardware-backed or biometric authenticators, you need an authenticator type. Etc, etc, etc.
If WebAuthn is hard to use, it's because we haven't build the right libraries and abstractions yet, and that indeed sucks. (Though I think we mostly have, and it's not that hard to use.)
But the criticism here of complexity--contrasted with the simplicity of a trivially broken, horribly unusable "proof of concept"--is a bit like someone who says "I can make a working demo of a car without power steering, antilock breaks, an entertainment unit, an ECU, a catalytic converter, or headlights--just four wheels and a two-stroke engine! Clearly all that complexity isn't needed!"
Having recently had to upgrade from u2f to webauthn, the complexity involved in getting webauthn right cannot be understated, especially when comparing it to something like OTP.
This flow seems simpler but more annoying for the end-user, right? They would have to generate the signed message themselves and then paste it into the browser. Whereas with webauthn you just touch your security key.
Ideally, we make WebAuthn easier to use (via libraries, identity providers, etc), rather than, you know, replacing it with something less secure than passwords.
Just sayin’. ;)
As good as WebAuthn is, research around PAKEs is currently the most exciting to me: https://blog.cloudflare.com/research-directions-in-password-...
I just wish browsers natively supported that authentication scheme to further defend against phishing and other attacks where the javascript implementation can be replaced.
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.
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.
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.
Think of it this way, users would be better off with ssh style login instead of passwords but the “industry” seems to have skipped that step for consumers and gone straight to hardware keys.
authviassh://authviassh@auth.server/origin.domain/nonce
authviassh:\/\/authviassh@(${domain_regex})/(${domain_regex})/([0-9a-zA-Z]+)
"Would you like to log into origin.domain (via auth.server) using ~/.ssh/your_key?"
ssh "authviassh@auth.server" -- authviassh "origin.domain" "nonce"
Only problem is, only 1 language has decent bindings for ssh interactives server-side, so one is somewhat forced to learn Go to implement this easily
- sign a challenge instead of a timestamp
- Make it effortless by using the FileSystem api to permanently point to a specific file on the device (until they move it)
- Use webcrypto to do the signing in-browser
- You can store a master private key that certifies new devices and can revoke old keys on the user's behalf or have them agree to generate one and store it off like (usb,etc... pw encrypted)
- what makes this better than using mutual TLS auth?
I know i posted late, hope you see this OP.
Author's solution adds some auth re-play protection, compared to what I use. But that's very little additional protection against threats that would be hardly a problem in practice for me. I just use TLS to protect the auth interaction (so who's going to capture the credentials?).
Most importantly, passwords actually work almost everywhere.