A study published in 2008 found data remanence in dynamic random-access memory (DRAM), with data retention of seconds to minutes at room temperature and much longer times when memory chips were cooled to low temperature. Another issue is storage of keys in the macOS "safe sleep" mode. Legacy FileVault used the CBC mode of operation (see disk encryption theory) FileVault 2 uses stronger XTS-AESW mode. Its security can be broken by cracking either 1024-bit RSA or 3DES-EDE. Several shortcomings were identified in legacy FileVault. Using Mac OS X Server as a Time Machine destination, backups of FileVault home directories occur while users are logged in.īecause FileVault restricts the ways in which other users' processes can access the user's content, some third party backup solutions can back up the contents of a user's FileVault home directory only if other parts of the computer (including other users' home directories) are excluded. In such cases, Time Machine is limited to backing up the home directory in its entirety. Without Mac OS X Server, Time Machine will back up a FileVault home directory only while the user is logged out. These limitations apply to versions of Mac OS X prior to v10.7 only. This can be mitigated to a certain extent by making symbolic links for these specific files. This encrypted image behaves similar to a FileVault encrypted home directory, but is under the user's maintenance.Įncrypting only a part of a user's home directory might be problematic when applications need access to the encrypted files, which will not be available until the user mounts the encrypted image. Instead of using FileVault to encrypt a user's home directory, using Disk Utility a user can create an encrypted disk image themselves and store any subset of their home directory in there (for example, ~/Documents/private). If transferring FileVault data from a previous Mac that uses 10.4 using the built-in utility to move data to a new machine, the data continues to be stored in the old sparse image format, and the user must turn FileVault off and then on again to re-encrypt in the new sparse bundle format. before migration, FileVault must be disabled at the source.If Migration Assistant has already been used or if there are user accounts on the target: the target must have no existing user accounts.there must be no prior migration to the target computer.Migration of FileVault home directories is subject to two limitations: If a user password is forgotten, the master password or recovery key may be used to decrypt the files instead. When FileVault is enabled the system invites the user to create a master password for the computer. The original version of FileVault was added in Mac OS X Panther to encrypt a user's home directory. For this approach to disk encryption, authorised users' information is loaded from a separate non-encrypted boot volume (partition/slice type Apple_Boot). This encrypts the entire OS X startup volume and typically includes the home directory, abandoning the disk image approach. Mac OS X Lion (10.7) and newer offer FileVault 2, which is a significant redesign. Apple refers to this original iteration of FileVault as legacy FileVault. Mac OS X Leopard and Mac OS X Snow Leopard use more modern sparse bundle disk images which spread the data over 8 MB files (called bands) within a bundle. The operating system uses an encrypted sparse disk image (a large single file) to present a volume for the home directory. 4 Starting the OS with FileVault 2 without a user accountįileVault was introduced with Mac OS X Panther (10.3), and could only be applied to a user's home directory, not the startup volume.
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