Anything · Lazarus or Delphi

Shredder-Files-Folders

An example of the irrevocable deletion of files and entire folders.

Active · last change 7-19-2026
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README

:computer: Shredder-Files-Folders:

Compiler 10 Seattle 10 1 Berlin 10 2 Tokyo 10 3 Rio 10 4 Sydney 11 Alexandria 12 Athens
Components None

A file shredder is a software tool that securely deletes files and folders by overwriting their data multiple times, making them unrecoverable by standard file recovery tools. This process protects sensitive information, such as financial or personal documents, by ensuring that deleted content is permanently erased from the hard drive rather than just removed from the file table. Many file shredders allow users to select specific files, folders, or even entire hard drives for deletion, often with features like drag-and-drop functionality and the ability to schedule shredding tasks.

:wrench: Features:

Shredder File
Shredder entire Folder, with all subfolders
Batch Shredder
Manipulate Attributes
Overwrite Directory Seperators
Overwrite Block Mode
Overwrite Bit Mode
Overwrite Bit random Mode

:wrench: Shredder Modes

Block Overwriting

When deleting a file, the pointer is removed without any changes to the blocks. But the list of blocks are marked free to be used whenever data is written. Considering no overwritten data. In this case, the block sectors are simply overwritten with a zero. Consider a fragmented filesystem like ext4 on a 512 Byte physical sector sized disk. File Recovery is pretty much useless when a deleted file's list of blocks cannot be known. If such thing is possible maybe it gives the disk little more life.

In this case, the optimal buffer size is 4096 kb.

Bits Overwriting

This function identifies all the bits of a file and replaces each one with binary data. This is significantly more thorough than a simple process, but consequently takes more time for the hard drive.

Random Overwriting

This function uses random number generators (often cryptographic random numbers) to fill the exact block on the hard drive with an insignificant sequence of zeros and ones. This takes place block by block; the program collects the blocks individually and overwrites them. The buffer size for this operation can be set separately.

⚙️: Functions

Overwriting:

Unlike simple deletion, which only removes file references, a file shredder replaces the file's data with random bits of information.

Multiple Passes:

Advanced file shredders use government-approved algorithms, such as the US Dod 5220.22-M method, to overwrite the data multiple times, further increasing security.

Data Recovery Prevention:

By thoroughly overwriting the data, file shredders prevent professional data recovery software from restoring the original content.

Secure Deletion:

The primary function is to permanently delete files, ensuring sensitive data cannot be recovered.

Batch Processing:

Many tools allow users to shred multiple files or folders at once.

Scheduling:

Some file shredders enable users to schedule tasks to automatically delete files at specific times or intervals.

Free Disk Space Cleaning:

Some programs offer features to securely clean free disk space, which may contain remnants of previously deleted but un-shredded files.

Support for Various Devices:

File shredders can often delete data from hard drives, SSDs, USB drives, and other storage media.

Restoring deleted data is usually possible, since deleting a file simply records in the file system that the corresponding data area is now free. However, the data itself remains physically on the hard drive until the area is overwritten with new data.

Once deleted, files can, under certain circumstances, be recovered using special programs. In addition, specialized data recovery and IT forensics companies offer their services to recover supposedly lost files.

So-called erasers are designed to "securely delete" files, preventing deleted data from being recovered through specialized interventions. Preventing such recovery requires overwriting the area on the data storage device freed up by the previous deletion. How often and in what form the relevant areas must be overwritten is highly controversial.

Original File:

After Shredder:

Directory Seperator:

In computing, a directory structure is the way an operating system arranges files that are accessible to the user. Files are typically displayed in a hierarchical tree structure.

A filename is a string used to uniquely identify a file stored on this structure. Before the advent of 32-bit operating systems, file names were typically limited to short names (6 to 14 characters in size). Modern operating systems now typically allow much longer filenames (more than 250 characters per pathname element).

File Attributes:

File attributes are a type of metadata that describe and may modify how files and/or directories in a filesystem behave. Typical file attributes may, for example, indicate or specify whether a file is visible, modifiable, compressed, or encrypted. The availability of most file attributes depends on support by the underlying filesystem (such as FAT, NTFS, ext4) where attribute data must be stored along with other control structures. Each attribute can have one of two states: set and cleared. Attributes are considered distinct from other metadata, such as dates and times, filename extensions or file system permissions. In addition to files, folders, volumes and other file system objects may have attributes.

Common File Attributes and Their Functions:

Attribute	Description
Read-only (R):	Prevents a file from being modified or deleted.
Hidden (H):	Hides the file from standard views in File Explorer, making it invisible during normal searches.
System (S):	Marks the file as a crucial operating system file, often hidden by default to prevent accidental changes.
Archive (A):	A flag used by backup systems to indicate that the file has been created or modified and may need to be backed up.
Normal (N):	Indicates the file has no special attributes.
Compressed (C):	Saves disk space by compressing the file.
Encrypted (E):	Secures the file's contents to prevent unauthorized access.
Directory (D):	A flag specific to folders.

The attrib command allows you to view and change attributes. For example,

attrib +h <filename>

hides a file, and

attrib -h <filename>

unhides it.

Folder Access Rights

Request folder permissions if they are not already present. Files with specific attributes in folders that require permissions may be rejected for deletion. To prevent this, specific rights can be granted to the folder beforehand to allow shredding.

To grant these rights, the string "Jeder" in the next code section must be renamed to the respective system language, e.g., the term "Anyone" for English.

pascal

if CheckBox3.Checked = true then
  begin
    AddAccessRights(PWideChar(Dir), 'Jeder', $FFFFFFFF);
  end;