GnuTLSEnable on

# based on <https://blog.joelj.org/ecdsa-certificates-with-apache-2-4-lets-encrypt/>
#  * only strong EC crypto suites supporting Perfect Forward Secrecy
#  * supported by all SNI-capable browsers
# Options:
#  * drop %SAFE_RENEGOTIATION for Safari 5.1.9 / OS X 10.6.8 support
#  * add 3DES-CBS after AES-128-CBC for Android 2.3.7 support on non-SNI hosts
#  * add CHACHA20-POLY1305 after ECDHE-ECDSA with libgnutls >= 3.4.0
GnuTLSPriorities NONE:+ECDHE-ECDSA:+AES-256-GCM:+AES-128-GCM:+AES-256-CBC:+AES-128-CBC:+AEAD:+SHA384:+SHA256:+SHA1:+CTYPE-X509:+VERS-TLS-ALL:-VERS-SSL3.0:+COMP-NULL:+CURVE-SECP384R1:+SIGN-ECDSA-SHA512:+SIGN-ECDSA-SHA384:+SIGN-ECDSA-SHA256:+SIGN-ECDSA-SHA224:%SERVER_PRECEDENCE:%SAFE_RENEGOTIATION

GnuTLSCertificateFile /etc/ssl/certs/apache2+cacert.org.pem
GnuTLSKeyFile /etc/ssl/private/apache2.pem

# HSTS: http://www.debian-administration.org/articles/662
Header add Strict-Transport-Security: "max-age=15768000;includeSubdomains"