From: http://www.tc.umn.edu/~brams006/selfsign.html
Complete this section if you do NOT want to make a CA (Certificate Authority).
Some steps in this document require priviledged access, and you'll want to limit access to the cert files to all but the root user. So you should su to root and create a working directory that only root has read/write access to (for example: mkdir certwork, chmod 600 certwork). Go to that directory.
openssl genrsa -des3 -out server.key 4096
openssl req -new -key server.key -out server.csr
openssl x509 -req -days 365 -in server.csr -signkey server.key -out server.crt
openssl rsa -in server.key -out server.key.insecure mv server.key server.key.secure mv server.key.insecure server.key