Original text:
<del> HTTP Unprompted Authentication </del>  draft-ietf-httpbis-unprompted-auth-latest Abstract <del> Existing HTTP authentication mechanisms are probeable in the sense that it is possible for an unauthenticated client to probe whether an </del>  origin serves resources that require authentication.  It is possible for an origin to hide the fact that it requires authentication by not generating Unauthorized status codes, however that only works with <del> non-cryptographic authentication schemes: cryptographic schemes (such as signatures or message authentication codes) require a fresh nonce to be signed, and there is no existing way for the origin to share such a nonce without exposing the fact that it serves resources that require authentication.  This document proposes a new non-probeable cryptographic authentication scheme. </del>  1. <del> Existing HTTP authentication mechanisms (see HTTP) are probeable in the sense that it is possible for an unauthenticated client to probe </del>  whether an origin serves resources that require authentication.  It is possible for an origin to hide the fact that it requires authentication by not generating Unauthorized status codes, however that only works with non-cryptographic authentication schemes: <del> cryptographic schemes (such as signatures or message authentication codes) require a fresh nonce to be signed, and there is no existing way for the origin to share such a nonce without exposing the fact that it serves resources that require authentication.  This document proposes a new non-probeable cryptographic authentication scheme. Unprompted Authentication serves use cases in which a site wants to offer a service or capability only to "those who know" while all others are given no indication the service or capability exists.  The conceptual model is that of a "speakeasy".  "Knowing" is via an externally-defined mechanism by which keys are distributed.  For example, a company might offer remote employee access to company </del>  services directly via its website using their employee credentials, or offer access to limited special capabilities for specific employees, while making discovering (probing for) such capabilities

Reviewer comments:
From Ilari Liusvaara on the : From NAME on the :
Maybe also consider for identification. That's not perfect, because of the "none" thing, but it might be a better fit. The TLS schemes are generally OK provided that you only use the recommended ones (of which there aren't many).
I don't love JWA since , but using TLS SignatureScheme with a requirement to only use the recommended ones sounds good to me.
NAME Doesn't it define the algorithm and then define the subkey types and in ?
NAME that could be made to work though it's quite clunky since it requires a separate string parameter for "alg". Overall I think the is a much better fit for signatures here. We already tightly integrate with TLS but not JWA. All that said, the closest option for hashes is the and that's been orphaned by RFC 8447. At this point I guess we should bite the bullet and define a new registry. Perhaps we include as current values: hmac-sha256 hmac-sha384 hmac-sha512 signature-rsapkcs1sha256 signature-rsapkcs1sha384 signature-rsapkcs1sha512 signature-ecdsasecp256r1sha256 signature-ecdsasecp384r1sha384 signature-ecdsasecp521r1sha512 signature-rsapssrsaesha256 signature-rsapssrsaesha384 signature-rsapssrsaesha512 signature-rsapsspsssha256 signature-rsapsspsssha384 signature-rsapsspsssha512 signature-ed25519 signature-ed448 Of course this requires to paint the bikeshed one of two colors: HMAC and Signatures in the same registry, using a single new auth scheme Separate registries, using separate auth schemes Thoughts? At this point I suspect this issue will need WG discussion at IETF 116.
I had to implement rsapsspss_shaX algorithms to produce test vectors for DCs, and unless there's a really compelling reason to include them, I'd really rather not. They're just such a pain to use, and the support for them is very poor (thus me needing to implement them).
FWIW, adding an entry in the registry doesn't mean it'll be mandatory to implement so there's not much of a cost. But I don't feel strongly about this one so I'm happy to not include it if it's the WG's preference.
Just saying here's a registry that you might could co-opt: URL Defined by URL
This is an existing registry of hash algorithms with string identifiers: URL Defined by URL
Discussed at IETF 116, sense of the room appeared to be that removing the HMAC feature entirely and switching to the TLS SignatureScheme registry for signatures was the simplest solution here.
OK wrote up to address this
Is there a technical reason why the header was not chosen for this draft? That can be sent without a corresponding challenge (in an unprompted way), as we note in the . It seems like that would work in this context, too.
Is this rather about using the Authorization header?
Yep!
NAME can you elaborate on "as we note in the "? I skimmed through that draft and it seems to clearly require a TokenChallenge before sending a Token.
I thought we had text that described it, but I can't find it. In any case, I think one can send the Authorization header unsolicited, so I think this draft ought to do that instead of rolling a new auth header.
Fair enough, let's discuss this at 116.
FWIW, I agree that unprompted "Authorization" is permissible in this context, but I think "Unprompted-Authorization" could be useful for clarity when reading logs, etc.
Discussed at IETF 116, sense of the room appeared to be that switching to Authorization made sense.
OK wrote up to address this

Revised text:
 <ins> The Signature HTTP Authentication Scheme </ins> draft-ietf-httpbis-unprompted-auth-latest Abstract  <ins> Existing HTTP authentication schemes are probeable in the sense that it is possible for an unauthenticated client to probe whether an </ins> origin serves resources that require authentication.  It is possible for an origin to hide the fact that it requires authentication by not generating Unauthorized status codes, however that only works with  <ins> non-cryptographic authentication schemes: cryptographic signatures require a fresh nonce to be signed, and there is no existing way for the origin to share such a nonce without exposing the fact that it serves resources that require authentication.  This document proposes a new non-probeable cryptographic authentication scheme. </ins> 1.  <ins> Existing HTTP authentication schemes (see HTTP) are probeable in the sense that it is possible for an unauthenticated client to probe </ins> whether an origin serves resources that require authentication.  It is possible for an origin to hide the fact that it requires authentication by not generating Unauthorized status codes, however that only works with non-cryptographic authentication schemes:  <ins> cryptographic signatures require a fresh nonce to be signed, and there is no existing way for the origin to share such a nonce without exposing the fact that it serves resources that require authentication.  This document proposes a new non-probeable cryptographic authentication scheme. The Signature HTTP authentication scheme serves use cases in which a site wants to offer a service or capability only to "those who know" while all others are given no indication the service or capability exists.  The conceptual model is that of a "speakeasy".  "Knowing" is via an externally-defined mechanism by which keys are distributed. For example, a company might offer remote employee access to company </ins> services directly via its website using their employee credentials, or offer access to limited special capabilities for specific employees, while making discovering (probing for) such capabilities