Translations:Dm-crypt full disk encryption/37/en

It is sometimes recommended to overwrite the whole disk with random numbers prior to setting up disk encryption. The rationale behind this recommendation is that reading an encrypted disk should leak as little information as possible. But if unused blocks (by the file system) are still all zero, an adversary can recover some high level information by determining which (encryption) blocks are likely used (because they contain random looking data) and which are unused (because they are, for example, all zero). The number and location of likely used encryption blocks can reveal information such as disk usage, the file system in use, or likely average file size.