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SpecificationsSignature-Key

Signature-Key

Status: Internet-Draft Spec: I-D.hardt-httpbis-signature-key

The foundation layer. A standalone HTTP specification (not AAuth-specific) that defines the Signature-Key header for conveying public keying material alongside HTTP Message Signatures (RFC 9421 ).

What It Does

Provides a standard way for a signer to tell a verifier which key to use. When a client signs an HTTP request, the verifier needs the public key to validate the signature. The Signature-Key header conveys that key inline with the request.

Primitives provided: key conveyance, signature verification bootstrapping

Why It Matters

Without Signature-Key, the verifier must already know the signer’s key — through pre-registration, a JWKS endpoint lookup, or some other out-of-band mechanism. Signature-Key makes HTTP Message Signatures self-contained: the signed request carries everything needed to verify it.

This is the building block that all AAuth signing depends on.

Read the Spec