_ESS_check_signing_certs() checks if the validation chain <i>chain</i> contains the certificates required by the identifiers given in <i>ss</i> and/or <i>ssv2</i>. If <i>require_signing_cert</i> is nonzero, <i>ss</i> or <i>ssv2</i> must not be NULL. If both <i>ss</i> and <i>ssv2</i> are not NULL, they are evaluated independently. The list of certificate identifiers in <i>ss</i> is of type <b>ESS_CERT_ID</b>, while the list contained in <i>ssv2</i> is of type <b>ESS_CERT_ID_V2</b>. As far as these lists are 