COSE Key Inspector
COSE_Key (RFC 8152) is the format WebAuthn uses for credentialPublicKey. Paste a CBOR map and this tool surfaces kty / alg / crv / x / y (or n / e for RSA) with field-by-field meaning.
Input
Decoded
Paste a COSE_Key.
All decoding runs locally.
About COSE_Key
COSE_Key is a CBOR map keyed by small integers: 1=kty, 2=kid, 3=alg. Per-key-type parameters use negative integer keys (e.g. -1=crv, -2=x, -3=y for EC2). The format is compact, self-describing, and crypto-suite agnostic — exactly what WebAuthn needs to ship a public key inside the attestation envelope.
Spec
RFC 8152 §7 (COSE Key Objects).
IANA registry
COSE algorithm and curve identifiers are tracked in the IANA COSE Algorithms registry.
Use
WebAuthn credentialPublicKey · CTAP2 messages · CWT (CBOR Web Tokens).