Nginx

You can configure nginx to use NetHSM via the OpenSSL engine which then uses NetHSM’s PKCS#11 module.

The certificate file has to be on the disk but the private key can be used from the NetHSM.

A full example is available below.

OpenSSL Configuration

Set up the OpenSSL engine by following the OpenSSL Engine setup guide.

Providers aren’t supported yet by Nginx.

Note

Using the libp11 OpenSSL engine version 0.4.12 or older and a NetHSM with a lot of key will make the initial loading of Nginx slow (more than a minute for 1 thousand keys). It is recommended to use version 0.4.13 or newer or to build the engine from source.

Nginx Configuration

ssl_engine pkcs11;

server {
    listen       443 ssl;
    server_name  localhost;

    ssl_certificate      /certs/certificate.pem;

    ssl_certificate_key "engine:pkcs11:pkcs11:object=webserver;type=private";

    ssl_session_cache    shared:SSL:1m;
    ssl_session_timeout  10s;
    ssl_session_tickets off;

    ssl_protocols TLSv1.3;
    ssl_prefer_server_ciphers  off;

    # HSTS (ngx_http_headers_module is required) (63072000 seconds)
    add_header Strict-Transport-Security "max-age=63072000" always;

    # OCSP stapling
    ssl_stapling on;
    ssl_stapling_verify on;

    location / {
        root   /usr/share/nginx/html;
        index  index.html index.htm;
    }

    error_page   500 502 503 504  /50x.html;
    location = /50x.html {
        root   /usr/share/nginx/html;
    }
}

The ssl_certificate must point to a certificate file on the disk.

The ssl_certificate_key can be an OpenSSL configuration. Here we use the OpenSSL engine with the PKCS#11 module and select the private key with the label/ID webserver and the key type private.

ssl_certificate_key "engine:pkcs11:pkcs11:object=webserver;type=private";

Note

You must generate the certificate separately and then upload it to the NetHSM. If the certificate on disk and the key in the NetHSM don’t match nginx won’t start.

libnethsm_pkcs11 Configuration

slots:
  - label: LocalHSM
    description: Local HSM (docker)
    url: "https://192.168.3.161:8443/api/v1"
    operator:
      username: "operator"
      password: "opPassphrase"

To secure the password you can provide it via an environment variable) or provide it in the nginx configuration:

ssl_certificate_key "engine:pkcs11:pkcs11:object=webserver;type=private;pin=opPassphrase";

Example

If you want to experiment with the given example use git to clone the nethsm-pkcs11 repository and run the following commands:

Warning

Running the generate script deletes the webserver key and replaces it.

  1. Configure a NetHSM, either a real one or a container. See the getting-started guide for more information. Besides an administrator, you are going to need an operator account.

  2. Download and install the latest version of the nethsm-pkcs11 driver available from here.

  3. Install the OpenSSL PKCS11 engine as described in the OpenSSL Manual. You do not need to create a configuration file.

  4. Adjust the variables HOST, ADMIN_ACCOUNT and ADMIN_ACCOUNT_PWD in container/nginx/generate.sh such that HOST contains your NetHSMs URL and port, ADMIN_ACCOUNT contains an administrator accounts username and ADMIN_ACCOUNT_PWD the corresponding password. Further configure the absolute path of the OpenSSL PKCS11 engine in OPENSSL_PKCS11_ENGINE_PATH and the absolute path of the NetHSM PKCS11 library in NETHSM_PKCS11_LIBRARY_PATH.

  5. Create a NetHSM PKCS11 configuration file in one of the known locations, e.g., /etc/nitrokey/p11nethsm.conf. It must have configured an operator account and use the same NetHSM instance specified in the generate script before.

  6. Update the PKCS11 configuration in container/nginx/p11nethsm.conf with your NetHSMs URL and valid operator credentials.

  7. Generate the certificate and key.

./container/nginx/generate.sh

  1. Build the container.

docker build -f container/nginx/Dockerfile . -t pkcs-nginx

  1. Run the container.

docker run -p 9443:443 -p 9080:80 pkcs-nginx

The NGINX test page will be available at https://localhost:9443/. Note that your browser, hopefully, will warn you that the websites certificate is self-signed.