certificateChain

The "x5c" (X.509 certificate chain) parameter contains a chain of one or more PKIX certificates (RFC5280). The certificate chain is represented as a JSON array of certificate value strings. Each string in the array is a base64-encoded (Section 4 of (RFC4648) -- not base64url-encoded) DER (ITU.X690.1994) PKIX certificate value. The PKIX certificate containing the key value MUST be the first certificate. This MAY be followed by additional certificates, with each subsequent certificate being the one used to certify the previous one. The key in the first certificate MUST match the public key represented by other members of the JWK. Use of this member is OPTIONAL.