Microsoft The W3C Web Authentication (WebAuthn) specification and the FIDO Alliance Client to Authenticator Protocol (CTAP) specification use CBOR Object Signing and Encryption (COSE) algorithm identifiers. This specification registers the following algorithms in the IANA "COSE Algorithms" registry, which are used by WebAuthn and CTAP implementations: RSASSA-PKCS1-v1_5 using SHA-256, SHA-384, SHA-512, and SHA-1, and ECDSA using the secp256k1 curve and SHA-256. It registers the secp256k1 elliptic curve in the IANA "COSE Elliptic Curves" registry. Also, for use with JSON Object Signing and Encryption (JOSE), it registers the algorithm ECDSA using the secp256k1 curve and SHA-256 in the IANA "JSON Web Signature and Encryption Algorithms" registry and the secp256k1 elliptic curve in the IANA "JSON Web Key Elliptic Curve" registry.