keyId

This parameter has the same meaning, syntax, and processing rules as the "kid" Header Parameter defined in Section 4.1.4 of (JWS), except that the key hint references the public key to which the JWE was encrypted; this can be used to determine the private key needed to decrypt the JWE. This parameter allows originators to explicitly signal a change of key to JWE recipients.

See JwsHeader.keyId