SSLEngine on SSLCertificateFile /etc/httpd/conf/login.domain.com.crt SSLCertificateKeyFile /etc/httpd/conf/login.domain.com.key SSLCipherSuite ALL:-ADH:+HIGH:+MEDIUM:-LOW:-SSLv2:-EXP
crt and key files represent both parts of a certificate, key being the private key to the certificate and crt being the signed certificate.
It's only one of the ways to generate certs, another way would be having both inside a pem file or another in a p12 container.
You have several ways to generate those files, if you want to self-sign the certificate you can just issue this commands
With a self-signed certificate however your browsers will warn you that the certificate is not "trusted" because it haven't been signed by a certification authority that is in the trust list of your browser, although it's a good way to get started.
From there onwards you can either generate your own chain of trust by making your CA or buy a certificate from a company like Verisign or Thawte.
These are the public (.crt) and private (.key) parts of an SSL certificate. See this question for a plethora of relevant information, e.g. if you want to generate a cert yourself, or buy one.