Table of Contents

Retrieving the Gandi Intermediate Certificate

You will want to download and install the intermediate certificate on your servers to ensure that your visitors can validate the trust chain all the way back to the root certificate. If your visitors use an older browser (pre-2010), they may not recognize the site as secure unless you have the intermediate certificate loaded.

Downloading the intermediate certificate

Intermediate certificates differ between Standard, Pro, and Business certificates.

The intermediate certificate must be installed on the server hosting the website that responds to the protected address, just like the Gandi certificate you were issued.

SHA1 Intermediate Certificates

SHA2 Intermediate Certificates

Comodo Cross-Signed Certificate

Not all web browsers have implemented the Root CA for SHA2 certificates. Consequently, it may be necessary to add the cross-signed certificate below to your server so that the client can verify the certification chain. The installation of the certificate depends on the program used. Recent versions of Chrome already support SHA2 certificates, Mozilla is in the process of adding it in the latest versions of Firefox (see the report at https://bugzilla.mozilla.org/show_bug.cgi?id=634074) as well as certain distributions. We recommend that you add the cross-signed certificate to your server in order to reduce the risk of incompatibility with your customers.

You may download the certificate in DER format at the following address: http://crt.usertrust.com/USERTrustRSAAddTrustCA.crt or recover it from the PEM format below: 

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

In order to use it, you will have to create a bundle with the Gandi SHA2 intermediate certificate.
In your bundle file :

-----BEGIN CERTIFICATE-----
XXXXXXXXX   <- intermediate certificate
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
XXXXXXXXX   <- cross-signed certificate
-----END CERTIFICATE-----

Once done, with Apache2 for instance, you will just have use the SSLCertificateChainFile directive and define localisation of your bundle file.
SSLCAcertificatefile won't be needed anymore in this case.

See Also