I have got a mail from one of our students, that she can not log in using SSO from Moodle. The Apache log said:
[Thu Oct 10 10:46:38 2013] [warn] [client 192.168.1.2] mod_fcgid: stderr: [WAR] fe (api/xmlrpc/client.php:173) Unknown error occurred: 710: Az al\xc3\xa1\xc3\xadr\xc3\xa1s-ellen\xc5\x91rz\xc3\xa9s sikertelen; az azonos\xc3\xadt\xc3\xa1st feltehet\xc5\x91leg nem \xc3\x96n \xc3\xadrta al\xc3\xa1., referer: http://moodle.appi.bme.hu/
[Thu Oct 10 10:46:38 2013] [warn] [client 192.168.1.2] mod_fcgid: stderr: Call stack (most recent first):, referer: http://moodle.example.org/
[Thu Oct 10 10:46:38 2013] [warn] [client 192.168.1.2] mod_fcgid: stderr: * Client->send("http://moodle.example.org") at /var/www/e-portfolio.appi.bme.hu/docs/auth/xmlrpc/lib.php:119, referer: http://moodle.example.org/
[Thu Oct 10 10:46:38 2013] [warn] [client 192.168.1.2] mod_fcgid: stderr: * AuthXmlrpc->request_user_authorise("f5d3148ab41b07113f47f79458596a5425b73895", "http://moodle.appi.bme.hu") at /var/www/e-portfolio.example.org/docs/auth/xmlrpc/land.php:94, referer: http://moodle.example.org/
The solution was to change the public keys on both Moodle and Mahara. After it the SSO worked again.