Therefore, do not fill space with zeros, simple patterns (like badblocks) or other non-random data before setting up block device encryption if you are serious about it. Warning: If block device encryption is mapped on a partition that contains non-random or unencrypted data, the encryption is weakened and becomes comparable to filesystem-level encryption: disclosure of usage patterns on the encrypted drive becomes possible. See also Wikipedia:Random number generation. To prepare a drive for block device encryption inside the wiped area afterwards, it is recommended to use #Random data generated by a cryptographically strong random number generator (referred to as RNG in this article from now on). Most notably, all Flash memory based devices and older magnetic storage (old HDDs, floppy disks, tape). There are different wiping issues with different physical storage technologies.

In case of a HDD, data recreation will not be possible without at least undocumented drive commands or tinkering with the device's controller or firmware to make them read out for example reallocated sectors (bad blocks that S.M.A.R.T. Any file recovery software mentioned above then would need to be specialized on proprietary storage-hardware features. If you want to quickly wipe everything from the disk, /dev/zero or simple patterns allow maximum performance while adequate randomness can be advantageous in some cases that should be covered up in #Data remanence.Įvery overwritten bit means to provide a level of data erasure not allowing recovery with normal system functions (like standard ATA/SCSI commands) and hardware interfaces. There may be (unencrypted) data left on the device and you want to protect against simple forensic investigation that is mere child's play with for example File recovery software. The most common usecase for completely and irrevocably wiping a device is when the device is going to be given away or sold. Common use cases Wipe all data left on the device Tip: References to 'disks' in this article also apply to loopback devices.

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