Network Security Hacks

Distribute Your CA to Clients

Be sure all of your clients trust your new Certificate Authority.

Once you have created a Certificate Authority (CA) [Hack #45] , any certificates that are signed by your CA will be trusted by any program that trusts your CA. To establish this trust, you need to distribute your CA’s certificate to each program that needs to trust it. This could include email programs, IPSec installations, or web browsers.

Since SSL uses public key cryptography, there is no need to keep the certificate a secret. You can simply install it on a web server and download it to your clients over plain old HTTP. While the instructions for installing a CA cert are different for every program, this hack will show you a quick and easy way to install your CA on web browsers.

There are two possible formats that browsers will accept for new CA certs: pem and der. You can generate a der from your existing pem with a single openssl command:

$ openssl x509 -in demoCA/cacert.pem -outform DER -out cacert.der

Also, add the following line to the conf/mime.types file in your Apache installation:

application/x-x509-ca-cert      der pem crt

Now restart Apache for the change to take effect. You should now be able to place both the cacert.der and demoCA/cacert.pem files anywhere on your web server and have clients install the new cert by simply clicking on either link.

Early versions of Netscape expected pem format, but recent versions will accept either. Internet Explorer is just the opposite (early ...