OptionalalgOptionalkey_OptionalkidThe kid (key ID) parameter is used to match a specific key.
Recommended that kid is set to the fingerprint of the public key.
OptionaluseThe parameter "x" MUST be present and contain the public key encoded using the base64url [RFC4648] encoding.
The parameter "y" MUST be present and contain the public key encoded using the base64url [RFC4648] encoding.
See
https://www.rfc-editor.org/rfc/rfc7518#section-6.2