Mozilla's Firefox and Thunderbird recently removed 1024-bit certificate authority (CA) certificates from their trusted store. This change was announced to the various certificate authorities in May of this year and shipped with Firefox 32 on September 2nd. This change was a long time coming, as the National Institute of Standards and Technology (NIST) recommended that 1024-bit RSA keys be deprecated in 2010 and disallowed after 2013.
more here..........https://community.rapid7.com/community/infosec/sonar/blog/2014/09/04/107000-web-sites-no-longer-trusted-by-mozilla
more here..........https://community.rapid7.com/community/infosec/sonar/blog/2014/09/04/107000-web-sites-no-longer-trusted-by-mozilla