As specified in Section 4.4 of the JWK specification, -the `alg` property identifies the algorithm intended for use with the public key, -and is included to prevent security issues that can arise when using the same +the OPTIONAL `alg` property identifies the algorithm intended for use with the public key, +and SHOULD be included to prevent security issues that can arise when using the same key with multiple algorithms. As specified in Section 6.2.1.1 of the JWA specification, describing a key using an elliptic curve, -the `crv` property is used to identify the particular curve type of the public key. +the REQUIRED `crv` property is used to identify the particular curve type of the public key. As specified in Section 4.1.4 of the JWS specification, -the `kid` property is a hint used to help discover the key; if present, the `kid` value SHOULD +the OPTIONAL `kid` property is a hint used to help discover the key; if present, the `kid` value SHOULD match, or be included in, the `id` property of the encapsulating `JsonWebKey` object, as part of the path, query, or fragment of the URL.