arently issued using (CA) certificate <i>issuer</i>. This function takes into account not only matching of the issuer field of <i>subject</i> with the subject field of <i>issuer</i>, but also compares all sub-fields of the <b>authorityKeyIdentifier</b> extension of <i>subject</i>, as far as present, with the respective <b>subjectKeyIdentifier</b>, serial number, and issuer fields of <i>issuer</i>, as far as present. It also checks if the <b>keyUsage</b> field (if present) of <i>issuer</i> allows certificate