If you use curl on a PPC you may have issues with it not recognizing valid SSL certificates. In that case it might be time to update the CA file. You can easily do this from the command line by renaming the original (just in case) and then downloading a current version from the internet using these two commands:
sudo mv /usr/share/curl/curl-ca-bundle.crt /usr/share/curl/curl-ca-bundle.crt-old
sudo curl https://curl.haxx.se/ca/cacert.pem -o /usr/share/curl/curl-ca-bundle.crt --insecure
sudo mv /usr/share/curl/curl-ca-bundle.crt /usr/share/curl/curl-ca-bundle.crt-old
sudo curl https://curl.haxx.se/ca/cacert.pem -o /usr/share/curl/curl-ca-bundle.crt --insecure
