This paper describes the first security evaluation of FileVault 2, a volume encryption mechanism that was introduced in Mac OS X 10.7 (Lion). The evaluation results include the identification of the algorithms and data structures needed to successfully read an encrypted volume. Based on the analysis, an open-source tool named libfvde was developed to decrypt and mount volumes encrypted with FileVault 2. The tool can be used to perform forensic investigations on FileVault 2 encrypted volumes. Additionally, the evaluation discovered that part of the user data was left unencrypted; this was subsequently fixed in the CVE-2011-3212 operating system update.