Function generate_key 

pub(crate) fn generate_key<D: Equivalence>(
    cx: &mut JSContext,
    global: &D::GlobalScope,
    normalized_algorithm: &KmacKeyGenParams,
    extractable: bool,
    usages: Vec<KeyUsage>,
) -> Result<DomRoot<CryptoKey<D>>, Error>

https://wicg.github.io/webcrypto-modern-algos/#kmac-operations-generate-key