Opaque, Interoperable Passkey Records (and a Go API)

Opaque, Interoperable Passkey Records (and a Go API)(words.filippo.io)

39 points by gnabgib 10 hours ago | 8 comments

From the linked spec,

> The authenticator data is a CBOR structure defined in the WebAuthn Level 3 specification, is returned by the getAuthenticatorData() method of the AuthenticatorAttestationResponse

From TFA,

> The payload is the authenticator data, a CTAP2 CBOR encoding of most of the credential record fields that is already specified by WebAuthn

Both link to the same section of the WebAuthn spec, §6.1 Authenticator Data[1]. Unless I'm missing something, that section is describing a custom binary format, not a CBOR encoding of data. (Though n.b. that one of the items contained by the outer custom binary format is CBOR, but the 37(ish) byte array itself is not CBOR.)

(…and it's stuff like that that just makes all of WebAuthn so impenetrable.)

[1]: https://www.w3.org/TR/webauthn-3/#sctn-authenticator-data

masklinn 3 hours ago | |

The article does not say it’s storing the authenticator data (in the format the webauthn spec specifies), it says it’s storing (most of) the fields in cbor. So it’s using the webauthn reference for logical purposes (the names and types of fields) not physical (the encoding).

cadamsdotcom 7 hours ago |

Ok so we are achieving interoperability by turning passkeys into strings.

You know what it's called when you store a secret string in your password manager?

A password.

gnabgib 7 hours ago | |

> You know what it's called when you store a secret string in your password manager?

You keep changing your comment, but on the off chance you're still throwing shade.. Filippo probably wrote your password manager (or the code it runs, or the code your docker/kube system runs), and the decoder on the other end.

miloignis 7 hours ago | |

That's his point - he's demonstrating a proposed standard that would make storing passkeys server-side almost as easy as passwords.

fastest963 6 hours ago | |

The user still needs to provide proof that they own the passkey in order to login. It's not like someone could hack the website, steal the "string" and use it to login.