1 pasada, escritura de ceros
This option overwrites with binary zeros (0x00).
1 pasada, datos aleatorios
This option overwrites with a single pass of random data.
3 pasadas, sobrescribir 3 veces antes de borrar
This option overwrites regular files before deleting them. Files are overwritten three times, first with the byte pattern 0xff, then 0x00, and then 0xff again, before they are deleted.
7 pasadas, estándar del departamento de defensa de U.S.
This option meets the U.S. Department of Defense DoD 5220.22-M (ECE) standard for securely erasing magnetic media. It erases the information used to access your files and writes over the data seven times (0xF6, 0x00, 0xFF, random data, 0x00, 0xFF, and random data).
35 pasadas, algoritmo Peter Gutmann
ADVERTENCIA:
You should not perform these operations on a solid-state drive or a Fusion Drive because the operations can reduce the lifespan of those drives.
Moreover, because the internal controller can make data reallocations to manage the wear of the blocks, it is difficult to know if previous copies of data do not exist.