This paper describes the Flush+Reload attack and its use for extracting the RSA private key from GnuPG. The attack is able to recover over 98% of the bits of the private key, virtually breaking the key, by capturing a single decryption or signing round. The attack requires the spy program and the victim to share pages, and can work over the isolation layer of virtualised systems.
Download the paper from here – http://eprint.iacr.org/2013/448.pdf