...
- (2018.02 build 87948 and later) a FEWS standalone (so not at an OC) - F12 - convert → convert → convert certificate file to truststore file.
- (older builds) the keytool.exe located in the jre/bin dir. Use a cmd prompt with something like: <location of fews bin>\jre\bin\keytool.exe -import -v -alias root -file <certificate file> -keystore <name>.truststore -storepass <pass>
...