Building OQS provider

All you have to do is clone the repository, build and install it.

For example:

git clone https://github.com/open-quantum-safe/oqs-provider
          cd oqs-provider
          mkdir build && cd build
          cmake -S ..
          cmake --build .
          sudo cmake --install .

Enabling OQS provider

Open your OpenSSL configuration (on Ubuntu it's located at /etc/ssl/openssl.cnf).

Just enable the provider by-default, this avoids the need to force software to specifically enable the OQS provider.

# List of providers to load
          [provider_sect]
          default = default_sect
          oqsprovider = oqsprovider_sect
          ...

          [default_sect]
          activate = 1

          [oqsprovider_sect]
          activate = 1

You can check the results using openssl list -kem-algorithms, it should list at least x25519_kyber768 @ oqsprovider.

Allowing Kyber hybrid KEMs

Next step is to enable the KEM in nginx's TLS configuration. No other changes need to be made if your distribution and nginx uses OpenSSL 3.

Locate the line that says ssl_ecdh_curve auto; and replace it with:

ssl_ecdh_curve x25519_kyber768:p384_kyber768:x25519:secp384r1:x448:secp256r1:secp521r1;

The first preference now being X25519Kyber768, then P384Kyber768 for Edge, X25519 for regular clients and the usual for compatibility after that.

After this change, just restart nginx (sudo systemctl restart nginx).

Checking if your browser has PQ KEM support

X25519Kyber768 has been available in Chrome since Chrome 115 (dev trial) and behind a flag after 118 (chrome://flags#enable-tls13-kyber). It's also behind a flag in Edge (edge://flags#edge-post-quantum-kyber). Chrome has also started a gradual rollout and they're at 10% (as of 30.11.2023).

You can test if your browser has Kyber enabled by visiting CloudFlare's test page. You should see kex=X25519Kyber768Draft00.

Besides this site I'm not aware of any that would allow one to test both QUIC and PQ KEMs simultaneously.

Firefox does not yet support X25519Kyber768Draft00, there has been some effort.

Result

If you visit your website with an enabled browser you should be seeing Kyber786 being used.

Edge will display something like this:

CloudFlare PQ origin pulls

If you use CloudFlare as a reverse proxy, then you can also enable X25519Kyber768 on the first attempt (to save a round trip) using their API:

curl --request PUT \
          --url https://api.cloudflare.com/client/v4/zones/[ ZONE_ID ]/id/cache/origin_post_quantum_encryption \
          --header 'Content-Type: application/json' \
          --header 'Authorization: Bearer [ API_TOKEN ]' \
          --data '{"value": "preferred"}'

External references

• https://pq-crystals.org/kyber/index.shtml
• https://www.ietf.org/archive/id/draft-tls-westerbaan-xyber768d00-02.html
• https://blog.cloudflare.com/post-quantum-to-origins/
• https://blog.chromium.org/2023/08/protecting-chrome-traffic-with-hybrid.html
• https://chromestatus.com/feature/5257822742249472
• https://crypto.cloudflare.com/cdn-cgi/trace
• https://github.com/open-quantum-safe/oqs-provider

Enabling TLS-only SMTP on port 465 with Postfix

Implicit TLS is generally considered a better approach to transport encryption than the usual explicit (STARTTLS) TLS everyone is used to, this is why I wanted to enable it in my Postfix.

In the end it's very easy to enable implicit TLS SMTP with Postfix, just add (or uncomment)

-o smtpd_tls_wrappermode=yes

In /etc/postfix/master.cf under smtps inet .... This will run the Postfix SMTP server in the "non-standard" "wrapper" mode, requiring establishing a TLS connection instantly instead of requiring use of the STARTTLS command and being potentially vulnerable to MITM.

It is however recommended to keep using port 25 as well and allow STARTTLS there, this use of port 465 (smtps) seems to actually be standardized in a way, but can confuse older machines, I had some ancient online test break.

NB! This feature is available in Postfix 2.2 and later, if you have an older Postfix version you should really update.

External references

• Git credential helper causes repository not found error - https://stackoverflow.com/questions/39239417/git-credential-helper-causes-repository-not-found-error
• Skip password when using https:// on GitHub https://stackoverflow.com/questions/5343068/is-there-a-way-to-skip-password-typing-when-using-https-on-github

External references

• http://www.geoffstratton.com/recompile-nginx-19-installed-apt-ubuntu-1604
• https://ops.tips/blog/nginx-http2-server-push/#installing-nginx-from-source
• https://www.slideshare.net/Nginx/modsecurity-30-and-nginx-getting-started
• https://github.com/SpiderLabs/ModSecurity-nginx
• https://serverfault.com/questions/777978/install-mod-security-for-nginx-without-need-to-recompile

Instructions

I started with downloading nginx's sources and extracting them: .. code-block:: bash

wget https://nginx.org/download/nginx-1.13.12.tar.gz tar -xf nginx-1.13.12.tar.gz

Then I took the compilation flags of my current nginx build with nginx -V, modified to include modsecurity and to excude useless modules (you can always find the sources of the modules online and pray they work with newer nginx, remove --add-module=./modules/ngx_brotli if you want nginx without brotli):

./configure --with-cc-opt='-g -O2 -fPIE -fstack-protector-strong -Wformat -Werror=format-security -Wdate-time -D_FORTIFY_SOURCE=2' --with-ld-opt='-Wl,-Bsymbolic-functions -fPIE -pie -Wl,-z,relro -Wl,-z,now' --sbin-path=/usr/sbin/nginx --prefix=/usr/share/nginx --conf-path=/etc/nginx/nginx.conf --http-log-path=/var/log/nginx/access.log --error-log-path=/var/log/nginx/error.log --lock-path=/var/lock/nginx.lock --pid-path=/run/nginx.pid --http-client-body-temp-path=/var/lib/nginx/body --http-fastcgi-temp-path=/var/lib/nginx/fastcgi --http-proxy-temp-path=/var/lib/nginx/proxy --http-scgi-temp-path=/var/lib/nginx/scgi --http-uwsgi-temp-path=/var/lib/nginx/uwsgi --with-debug --with-pcre-jit --with-http_ssl_module --with-http_stub_status_module --with-http_realip_module --with-http_auth_request_module --with-http_addition_module --with-http_dav_module --with-http_flv_module --with-http_geoip_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_image_filter_module --with-http_mp4_module --with-http_perl_module --with-http_random_index_module --with-http_secure_link_module --with-http_v2_module --with-http_sub_module --with-http_xslt_module --with-mail --with-mail_ssl_module --with-stream --with-stream_ssl_module --with-threads --add-module=./modules/headers-more-nginx-module --add-module=./modules/ModSecurity-nginx --add-module=./modules/ngx_brotli --with-compat

Building it is easy after that: .. code-block:: bash

make -j3 make install

Then I only had to restart nginx: .. code-block:: bash

sudo systemctl restart nginx

Configuration is left as an excercise for the reader :)

Usability

I tested it out for a while, it has a few bugs and the documentation is really lacking in terms of how to write brand-new rules for it. It's also super annoying to detect false-positives and I found the rule syntax vomit-worthy. I decided to drop using modsecurity, it just wasn't worth it, especially not just for fun™.

This also seems to hold true in 2023 as it did back in 2018.