--- title: Opaque, Interoperable Passkey Records (and a Go API) description: Filippo Valsorda proposes an interoperable passkey record format (c2sp.org/passkey-record) that encodes WebAuthn credential data as opaque strings similar to... canonical: https://daily.dev/posts/opaque-interoperable-passkey-records-and-a-go-api--rq5b1tii7 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Opaque, Interoperable Passkey Records (and a Go API) | daily.dev og:description: Filippo Valsorda proposes an interoperable passkey record format (c2sp.org/passkey-record) that encodes WebAuthn credential data as opaque strings similar to... og:url: https://daily.dev/posts/opaque-interoperable-passkey-records-and-a-go-api--rq5b1tii7 og:image: https://api.daily.dev/og/posts/RQ5B1TII7.png og:image:alt: Opaque, Interoperable Passkey Records (and a Go API) og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Opaque, Interoperable Passkey Records (and a Go API) **[Filippo Valsorda](https://daily.dev/sources/filippo)** · 7 min read · 4 upvotes · 1 comments ## Summary Filippo Valsorda proposes an interoperable passkey record format (c2sp.org/passkey-record) that encodes WebAuthn credential data as opaque strings similar to password hash strings. The format uses PHC string syntax with base64-encoded authenticator data as the payload and transports as parameters. This abstraction lets applications treat passkeys like password hashes — storing opaque strings without needing to understand the internal structure — while remaining library- and backend-agnostic. A draft Go API (crypto/passkey) is also proposed, covering registration and login flows with a stateless design. The post also argues that the common recommendation to enforce unique Credential IDs across accounts is unnecessary when lookups are keyed by user ID rather than credential ID. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Community discussion Top comments from developers on daily.dev. **@trevorsuna** · 0 upvotes > Treating a passkey record like an opaque password hash is a neat boundary. It keeps apps out of WebAuthn internals and should make switching libraries or backends far less painful. ## Similar posts on daily.dev - [Using Passkeys to Sign In to Websites and Apps](https://daily.dev/posts/using-passkeys-to-sign-in-to-websites-and-apps-cbz70me3e) · Security Boulevard · 0 upvotes · 0 comments - [Modernize authentication with passkeys, digital credentials, and more](https://daily.dev/posts/modernize-authentication-with-passkeys-digital-credentials-and-more-nzvsxhett) · Chrome Developers · 1 upvotes · 0 comments --- Tags: [#security](https://daily.dev/tags/security), [#golang](https://daily.dev/tags/golang), [#authentication](https://daily.dev/tags/authentication), [#passkeys](https://daily.dev/tags/passkeys) [View this post on daily.dev](https://daily.dev/posts/opaque-interoperable-passkey-records-and-a-go-api--rq5b1tii7) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Opaque, Interoperable Passkey Records (and a Go API)","url":"https://daily.dev/posts/opaque-interoperable-passkey-records-and-a-go-api--rq5b1tii7","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/opaque-interoperable-passkey-records-and-a-go-api--rq5b1tii7"},"datePublished":"2026-07-21T00:01:37.226Z","dateModified":"2026-07-21T02:42:55.137Z","description":"Filippo Valsorda proposes an interoperable passkey record format (c2sp.org/passkey-record) that encodes WebAuthn credential data as opaque strings similar to...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/f29b0f6a39c7ddb7c075e54edd860268?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/f29b0f6a39c7ddb7c075e54edd860268?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Filippo Valsorda","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Filippo Valsorda","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/3ade50bc05994d7ea5ad5ab5ab8e60aa","url":"https://daily.dev/sources/filippo"},"commentCount":1,"discussionUrl":"https://daily.dev/posts/opaque-interoperable-passkey-records-and-a-go-api--rq5b1tii7","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":4},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":1}],"keywords":"security,golang,authentication,passkeys","timeRequired":"PT7M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Filippo Valsorda","item":"https://daily.dev/sources/filippo"},{"@type":"ListItem","position":3,"name":"Opaque, Interoperable Passkey Records (and a Go API)"}]} {"@context":"https://schema.org","@type":"WebPage","@id":"https://daily.dev/posts/opaque-interoperable-passkey-records-and-a-go-api--rq5b1tii7","comment":[{"@type":"Comment","text":"Treating a passkey record like an opaque password hash is a neat boundary. 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