Private CA and self-signed certs that work with Chrome

This method is for testing and development only. The vast majority of users should not use this method, as it requires loading a cert on each of your devices, which is both error-prone and requires future maintenance. Instead, focus your energy on obtaining real certs via Let's Encrypt. This can even work if your vaultwarden instance is not on the public Internet (Example | Running-a-private-vaultwarden-instance-with-Let's-Encrypt-certs).

This method is not supported. Please do not open GitHub issues or post on the discussion forums asking about how to get this to work.

To get docker-based websites working properly with self-signed certificates, Chrome needs the certificate to include the domain name in the alternative name field of the certificate.

• Create a CA key (your own little on-premise Certificate Authority):

openssl genpkey -algorithm RSA -aes128 -out private-ca.key -outform PEM -pkeyopt rsa_keygen_bits:2048

Note: instead of -aes128 you could also use the older -des3.

• Create a CA certificate:

openssl req -x509 -new -nodes -sha256 -days 3650 -key private-ca.key -out self-signed-ca-cert.crt

Note: the -nodes argument prevents setting a pass-phrase for the private key (key pair) in a test/safe environment, otherwise, you'll have to input the pass-phrase every time you start/restart the server.

• Create a website key:

openssl genpkey -algorithm RSA -out website.key -outform PEM -pkeyopt rsa_keygen_bits:2048

• Create the website certificate request file:

openssl req -new -key website.key -out website.csr

• Create a text file website.ext with the following content, and change the domain names to your setup.

authorityKeyIdentifier=keyid,issuer
basicConstraints=CA:FALSE
keyUsage = digitalSignature, nonRepudiation, keyEncipherment, dataEncipherment
extendedKeyUsage = serverAuth
subjectAltName = @alt_names

[alt_names]
DNS.1 = website.local
DNS.2 = www.website.local

• Create the website certificate, signed from the root CA:

openssl x509 -req -in website.csr -CA self-signed-ca-cert.crt -CAkey private-ca.key -CAcreateserial -out website.crt -days 365 -sha256 -extfile website.ext

Note: As of April 2019 iOS 13+ and macOS 15+, the server certificate can not have an expiry > 825 and must include the ExtendedKeyUsage extension (refer).

Add the root certificate and the website certificate to client computers.

Add the self-signed-ca-cert.crt generated to client web browsers.

Add website.crt, website.key to the corresponding website or proxy manager.

Reference

For reference, see here