This object represents a secret key (symmetric key) or secret data in a secure element that is encrypted for the recipient of the manifest.
It is a JSON Web Encryption (JWE) object, as defined by RFC 7516. The JWE payload will be the JSON serialization (not compact
serialization) of a JWK object, as defined by RFC 7517, with a key type of octet ("kty":"oct"). See RFC 7518 section 6.4 for details on the symmetric key JWK.
This technique is described in RFC 7517 section 7.