5.5. Using HSMs protecting private keys in Nginx

The Nginx HTTP server can work with private keys stored on hardware security modules (HSMs), which helps to prevent the keys' disclosure and man-in-the-middle attacks. Note that this usually requires high-performance HSMs for busy servers.

Because Nginx also uses the OpenSSL for cryptographic operations, support for PKCS #11 must go through the openssl-pkcs11 engine. Nginx currently supports only loading private keys from an HSM, and a certificate must be provided separately as a regular file. Modify the ssl_certificate and ssl_certificate_key options in the server section of the /etc/nginx/nginx.conf configuration file:

ssl_certificate     /path/to/cert.pem
ssl_certificate_key "engine:pkcs11:pkcs11:token=softhsm;id=%01;type=private?pin-value=111111";

Note that the engine:pkcs11: prefix is needed for the PKCS #11 URI in the Nginx configuration file. This is because the other pkcs11 prefix refers to the engine name.