Securely Deleting Encrypted Data on Linux

Confirm the size and permissions of the file:

[cloud_user@$host]$ sudo ls -l /mnt/patient.1

Show the contents of the file:

[cloud_user@$host]$ sudo cat /mnt/patient.1

Be sure to double check the path, as this command does no error checking and will overwrite data:

[cloud_user@$host]$ sudo dd if=/dev/urandom of=/mnt/junk status=progress; sync

The shred command is the simplest method. Specifying -x ensures that the filesize remains unchanged:

[cloud_user@$host]$ sudo shred -x /mnt/patient.1

If the shred command is not available, we can use the following dd command:

[cloud_user@$host]$ sudo dd if=/dev/urandom of=/mnt/patient.1 bs=45 count=1 iflag=fullblock status=progress

Show file contents:

[cloud_user@$host]$ sudo cat /mnt/patient.1

Remove file:

[cloud_user@$host]$ sudo rm /mnt/patient.1

Remove junk file:

[cloud_user@$host]$ sudo rm /mnt/junk