If the remote resource that your Artifactory remote repository is proxying (e.g. Red Hat Network's server) uses an untrusted server certificate (i.e. it is self-signed and not signed by any known Certificate Authority), you need to import the server's certificate into Artifactory's JVM truststore. To learn more about configuring a Self-Signed Certificate in Artifactory, see Trust a Signed Certificate or a New CA.
You cannot configure a self-signed certificate in Artifactory SaaS
If you are using Artifactory SaaS (as opposed to an self-hosted installation), you will not be able to proxy resources that use untrusted (i.e. ,self-signed) certificates since you do not have access to the Artifactory SaaS JVM truststore.