PublicKeyCredentialJSON is an invalid WebIDL construct

[petervanderbeken]

typedef (RegistrationResponseJSON or AuthenticationResponseJSON) PublicKeyCredentialJSON;

is invalid WebIDL. RegistrationResponseJSON and AuthenticationResponseJSON are both dictionaries and thus not distinguishable, and WebIDL unions require each pair of flattened members in a union to be distinguishable.

Replacing PublicKeyCredentialJSON with object would work (with prose describing it's either RegistrationResponseJSON and AuthenticationResponseJSON), or there might be a solution with merging RegistrationResponseJSON and AuthenticationResponseJSON into one dictionary type somehow (would probably require some creativity with required/optional members in various dictionaries).

[MasterKale]

Thanks for pointing this out. WebIDL is so tricky to get right 😅

Replacing PublicKeyCredentialJSON with object would work (with prose describing it's either RegistrationResponseJSON and AuthenticationResponseJSON)

I can submit a PR that aims to take things this direction. I'd hate to have to mash up everything into a single dictionary as I think it'd be quite messy for RP's to work with.

[arianvp]

I actually found the union awkward when translating this to go. These are the types my RP uses in Go. Perhaps we can use it as inspiration for the IDL

type PublicKeyCredential struct {
	ID                      Base64URLString                       `json:"id"`
	AuthenticatorAttachment string                                `json:"authenticatorAttachment"`
	ClientExtensionResults  AuthenticationExtensionsClientOutputs `json:"clientExtensionResults"`
	Type                    string                                `json:"type"`
	Response                Response                              `json:"response"`
}

type Response struct {
	AuthenticatorAttestationResponse
	AuthenticatorAssertionResponse

	ClientData        Base64URLString `json:"clientDataJSON"`
	AuthenticatorData Base64URLString `json:"authenticatorData"`
}

type AuthenticatorAttestationResponse struct {
	AttestationObject  Base64URLString `json:"attestationObject"`
	Transports         []string        `json:"transports"`
	PublicKey          Base64URLString `json:"publicKey"`
	PublicKeyAlgorithm string          `json:"publicKeyAlgorithm"`
}

type AuthenticatorAssertionResponse struct {
	Signature  Base64URLString  `json:"signature"`
	UserHandle *Base64URLString `json:"userHandle"`
}

[MasterKale]

I'm going to work on getting something ready for review by the next WG meeting.