Teamwork Server recognizes certificates stored in Java KeyStore (JKS) format. If certificates are in PEM format, they must be converted to JKS format. You can use OpenSSL (http://www.openssl.org/) and Sun Java KeyTool (included with every Java distribution) for this purpose. For example, if we have a certificate in a file called cert.pem, then the following commands will covert it to JKS format:
openssl x509 -in cert.pem -out cert.der -outform der
keytool -importcert -alias mycert -file cert.der -keystore truststore.jks