certificateUrl

The "x5u" (X.509 URL) parameter is a URI (RFC3986) that refers to a resource for an X.509 public key certificate or certificate chain (RFC5280). The identified resource MUST provide a representation of the certificate or certificate chain that conforms to RFC 5280 (RFC5280) in PEM-encoded form, with each certificate delimited as specified in Section 6.1 of RFC 4945 (RFC4945). The key in the first certificate MUST match the public key represented by other members of the JWK. The protocol used to acquire the resource MUST provide integrity protection; an HTTP GET request to retrieve the certificate MUST use TLS (RFC2818) (RFC5246); the identity of the server MUST be validated, as per Section 6 of RFC 6125 (RFC6125). Use of this member is OPTIONAL.