ers may fail in this case, resulting for instance in HTTP error code 500 (Internal error).</p>

</li>
<li><p>OSSL_CRMF_POPO_RAVERIFIED - RFC 4211, section 4, explicit indication that the RA has already verified the POP.</p>

</li>
<li><p>OSSL_CRMF_POPO_SIGNATURE - RFC 4211, section 4.1, only case 3 supported so far.</p>

</li>
<li><p>OSSL_CRMF_POPO_KEYENC - RFC 4211, section 4.2, only indirect method (subsequentMessage/enccert) supported, challenge-response exchange (challengeResp) not yet supported.</p>

<