chanisms only support the following operation:</p>

<dl>

<dt id="DHKEM-OSSL_KEM_PARAM_OPERATION_DHKEM">&quot;DHKEM&quot; (<b>OSSL_KEM_PARAM_OPERATION_DHKEM</b>)</dt>
<dd>

<p>The encapsulate function generates an ephemeral keypair. It produces keymaterial by doing an X25519 or X448 key exchange using the ephemeral private key and a supplied recipient public key. A HKDF operation using the keymaterial and a kem context then produces a shared secret. The shared secret and the ephemeral public key are returne