I tried to install cocoapods (http://cocoapods.org/) on my OSX Mountain Lion.
moshe-mbp:~ moshem$ gem install cocoapods
ERROR: Could not find a valid gem
This is what solved it for me: Install this certificate: https://raw.githubusercontent.com/rubygems/rubygems/master/lib/rubygems/ssl_certs/AddTrustExternalCARoot-2048.pem
In this folder: {rubyfolder}\lib\ruby\2.1.0\rubygems\ssl_certs
This way you don't have to add insecure sources.
More info here: https://gist.github.com/luislavena/f064211759ee0f806c88