Generate new TLS/SSL certificates and keys and add them to your list of 'trusted certificates' in OS X Keychain

httpd-vhost.conf

<VirtualHost *:443>
    UseCanonicalName Off
    DocumentRoot "/Users/fleming/Sites/example"
    ServerName example.fleming
    SSLEngine on
    SSLCertificateFile "/Users/fleming/Sites/example/ssl.crt"
    SSLCertificateKeyFile "/Users/fleming/Sites/example/ssl.key"
</VirtualHost>

ssl.sh

#!/bin/bash -e

# https://gist.github.com/jed/6147872
# https://gist.github.com/jonathantneal/774e4b0b3d4d739cbc53

echo "Creating OpenSSL configuration."

cat > openssl.cnf <<-EOF
  [req]
  distinguished_name = req_distinguished_name
  x509_extensions = v3_req
  prompt = no
  [req_distinguished_name]
  CN = *.${PWD##*/}.$(whoami)
  [v3_req]
  keyUsage = keyEncipherment, dataEncipherment
  extendedKeyUsage = serverAuth
  subjectAltName = @alt_names
  [alt_names]
  DNS.1 = *.${PWD##*/}.$(whoami)
  DNS.2 = ${PWD##*/}.$(whoami)
EOF

echo "Generating new certificate."

openssl req \
  -new \
  -newkey rsa:2048 \
  -sha1 \
  -days 3650 \
  -nodes \
  -x509 \
  -keyout ssl.key \
  -out ssl.crt \
  -config openssl.cnf

echo "Cleaning up configuration file."
rm openssl.cnf

echo "Trusting new certificate."
sudo security add-trusted-cert -d -r trustRoot -k /Library/Keychains/System.keychain $(pwd)/ssl.crt

echo "Success."