Certificates that are used for encryption key servers

When you enable encryption with key servers, two types of certificates are required to ensure secure communication between the system and the encryption key server.

Certificates are the primary method that is used by the key servers to authenticate the system and for the system to authenticate to the key servers. The exchange of these certificates verifies that access to the encryption keys that are stored on the key servers is allowed. The authentication of the system ensures that the key servers do not give access to keys to an untrusted party. The authentication of the key servers ensures that the system does not ask for sensitive keys to be stored by an untrusted party. Security of the system relies on two factors. First, the public certificates of the key servers and the system must be exchanged securely so that each device can trust the other. Second, the key servers and the system must keep their private key, which is associated with the certificate, secure.

The key server certificates, which are used by the system to verify the key servers, must be transferred to the system and installed. When you are adding key servers to the system, either a certificate that is signed by a trusted third party, or a self-signed certificate can be used. A combination of these certificates can be used if you are adding more than one key server. If a combination of self-signed and CA-signed certificates are installed, then the self-signed key server certificates that are installed on the system take priority over any CA-signed key server certificates that are installed on the system.

Note: Thales CipherTrust Manager does not support a self-signed system certificate. Only CA-signed certificates can be used by Thales CipherTrust Manager key servers.

If all key servers are using a certificate that is signed by the same certificate authority, it is recommended that the CA certificate is installed in the key server type’s settings (for example, chkeyserverisklm -sslcert …) rather than the key server endpoints (for example, mkkeyserver -sslcert …). The CA certificate for the key server type’s settings is used only when you connect to a key server if the key server endpoint does not have a certificate that is installed. If you are using individual self-signed certificates for each key server, the certificates are installed against each key server endpoint. If you are using key server certificates that are part of a chain of trust, see Using certificate chains for key servers.

If the key servers are part of the same system and are configured to replicate their keys and certificates with each other, then the key server certificates are copied to all of the key servers. The system can connect to all key servers with the same server certificate. In addition, the system’s certificate must be installed on each of the configured key servers. The key server administrator accepts the system certificate to grant access to the key servers. To configure the system certificate for secure communications, select Settings > Security > Secure Communications.

Using certificate chains for key servers

In order for the system to authenticate by using SSL with a key server that uses signed certificate chains, the system requires multiple certificates to be installed. All certificates in the certificate chain (excluding the server certificate itself, that is, the leaf certificate) must be installed. For example, if a key server X’s certificate is signed by certificate authority Y, where certificate authority Y’s certificate is signed by Root certificate authority Z, then the system requires the certificates Y and Z to be installed on the system to successfully communicate with key server X. To install this certificate, create a single certificate file that contains the full chain of certificates, excluding the key server's certificate. The first certificate in the file is the CA certificate, which was used to sign the leaf of the certificate chain (the key server certificate). The last certificate in the file is the root CA certificate. In between the first certificate in the file and the root certificate, all of the intermediate CA certificates are specified in order. If multiple intermediate certificates exist, include these certificates in order from leaf to root.

The resulting certificates file must contain the first intermediate certificate at the top of the file, followed by subsequent intermediate CA certificates in order, one-by-one. Finally, the root CA certificate is last at the bottom of the file. The resulting file contains only the PEM data for each certificate with anything else, such as comments, removed from the file. Each certificate in the file is separated by a new line and each certificate begins with the header “-----BEGIN CERTIFICATE-----” and end with “-----END CERTIFICATE-----”.

An example certificate file, for a certificate chain of depth 3, might look like the following example. The example includes two certificates. The included certificates are the intermediate CA certificate Y first, followed by the root CA certificate Z. The key server certificate X is not included. If a bigger certificate chain is used, then more intermediate CA certificates would be included in the certificate file.