For details see http://docs.reductivelabs.com/guides/installation.html#verifying_installation

on the puppetmaster:

# list certificate requestes:
puppetca --list
 
# sign a request
puppetca --sign host.example.com
 
# revoke a certificate:
puppetca --revoke host.example.com
 
# clean a certificate:
puppetca --clean host.example.com

check certificate content:

openssl x509 -text -in /var/lib/puppet/ssl/certs/puppet.pem