Shredding everything: files/folders and corresponding filenames

filesSecurity

Using find, it is easy to shred a directory's contents recursively (as discussed in this question). However, sometimes the filenames on their own carry sensitive information already. Is there a way to shred everything associated with some file/directory, i.e. it overwrites both file contents and file/directory names in each cycle?

Best Answer

shred is mostly useless. In order to remove the content of a deleted file from the disk image, it isn't enough to overwrite the places where the file was: you need to remove all copies of the file. It's not just a matter of the file having been overwritten in place. With many types of files, there can have been multiple files with mostly the same content, because the file was edited and there are deleted backup copies left around.

Additionally, if the disk becomes damaged, it may be impossible to read the data by software means, but still possible to recover it by hardware means, or by letting the disk cool down (putting a hard disk in a freezer makes it less error-prone for a little while, until it finally gives up the ghost).

The safe way to shred a file is to store it from the start inside an encrypted container protected by a strong password (generate a long enough, random password, and write it down; when you're finished with the file, burn the piece of paper). Scrub your filesystem completely (back up the data, then overwrite it with zeroes), then create an ecryptfs container and restore your files. Don't forget to scrub the backup once you're sure the restoration was successful, or stow the backup in a secure place.

Related Solutions

Files – Replace Duplicate Files with Hardlinks

There is a perl script at http://cpansearch.perl.org/src/ANDK/Perl-Repository-APC-2.002/eg/trimtrees.pl which does exactly what you want:

Traverse all directories named on the command line, compute MD5 checksums and find files with identical MD5. IF they are equal, do a real comparison if they are really equal, replace the second of two files with a hard link to the first one.

Find the files between two folder dates in linux

Try this:

touch -d"April 13 3 AM" file1
touch -d"April 13 9 AM" file2
find . -newer file1 ! -newer file2 -exec grep -l "pcV6URY" {} +
rm file1 file2

How it works

find can work directly with times but touch handles human-style dates better:

touch -d"April 13 3 AM" file1; touch -d"April 13 9 AM" file2

This creates two files to mark the beginning and end of the time range.
find . -newer file1 ! -newer file2 -exec grep -l "pcV6URY" {} +

This finds files newer than file1 but not newer than file2. For all such files, it runs grep on them to see if they contain your string.

Best Answer

Related Solutions

Files – Replace Duplicate Files with Hardlinks

Find the files between two folder dates in linux

How it works

Related Question