Parameter and Command Reference > Secure Socket Layer Parameters > SSLCheckCertificate 

Specifies whether a certificate signed by a trusted authority is requested from peers.
Setting SSLCACertificate implicitly sets SSLCheckCertificate to true. If SSLCACertificate is set to false, communications are encrypted, but certificates are not requested from peers.
True if SSLCACertificate is set.
False if SSLCACertificate is not set.