Dummy File Creator

Dummy File Creator, A simple program which generates files of any size with ease. Very useful for disk speed test, CD burning test, network speed test, or simply create files to fool your friends. This program also has a built-in random function, so users can choose to create either compressible or non-compressible files.

Download (w installer): dummy12_setup.msi (391KB)
Download (w/o installer): (23KB)
Version: 1.2
Last Update: 2008/05/17
File Size (w/ installer): 391KB
File Size (w/o installer): 23KB
License: Freeware*
Developer: Nikko Cheng
Minimum Req: Windows(All)**
* For educational and non-commerical personal use only.
** Dummy File Creator requires Microsoft .NET Framework 2.0 Redistributable Package.
Introduction - Why Dummy File Creator?

The idea was simple: a dummy file. Usually, a warez FTP site would include a dummy file of exactly 1 MB for people to test the speed of the FTP server. Dummy File Creator fits right in the spot; it can easily create a file of any size for testing network speed, or data transfer rate of a disk drive. Also, Devices like hard drives have different data transfer rates at different physical location on the disk. For example, You will get different data transfer rates from the same 100GB hard drive when it's empty and when it's 80% full (defragged). With Dummy File Creator, you can easily fill your hard drive with 80GB of data and do the speed measurement again to compare.

However, Dummy File Creator is not only useful for speed testing; it is also useful to make fake files. Why would you need such fake files?
  • Prevent easy spread of illegal copies of your software - Imagine you just publish a new software with a size of 56MB onto a CD. You can fill the the remaining 644MB free CD space with fake files. If you cannot stop the crackers, you can still slow them down. People who try to transfer your software over the internet will have to spend longer time, while the authentic users who purchased your CD will not be affected.

  • Fool people on peer-to-peer file sharing networks - Although most peer to peer network programs have built-in CRC/Hashing check to prevent malicious fake files, a person can still share fake files with the same file name or catching program/media title to confuse P-to-P users.

  • Enhance protection of exsiting encryption - put a few fake files with randomly generated content along with your encrypted files. Investigators will have tough time finding/decrpyting your files, since they won't even know which one to start with!

  • Test drive fitness - simply fill up the drive with a large dummy file. Any bad sector will result an write error.

  • Wipe data to prevent file recovery - Have important data that you want to make sure it's deleted beyond recovery? Simply fill the drive after deletion/formation with a large dummy file. Normal file deletion or disk formation procedures only modify the file allocation table (FAT) to make the space available for writing without actually removing the data, so it makes data recovery possible by scanning through the entire disk to look for remaining data traces. By filling up those available spaces with dummy file contact, it overwrites all the those data traces with dummy file content.
What's new in version 1.2

  • A complete rewrite using Microsoft Visual Studio .NET 2005.
  • Improved random content generation, so it as fast as uncompressible content.
  • File generation is now using thread, so cancel the process anytime you want.
  • Added writing speed display for easy-monitoring the current writing speed.
  • Now supports batch file generation, you can now use a batch list to create dummy files.
  • Dummy File Creator Commandline Edition is also included in the package (DummyCMD.exe) for those command prompt lovers.
Manual - How to use?
It's easy! Simply:
  1. Execute Dummy File Creator
  2. Input desired file size (integer) and unit
  3. Click on "Browser" (ALT+B) to choose desired file name and location
  4. Click on the check box(ALT+R) if you want a file with randomly generated content
  5. Click on create (ALT+C) and the program will start generating a file
  6. The program will stop when the progress bar reaches 100%
  7. Click on "Exit" (ALT+X) to quit this program
Commandline Edition (DummyCMD.exe) Usage Example

Dummy File Creator 1.2 Commandline Edition
Copyright c 2008 Nikko Cheng
Generates a dummy file

C:\>DummyCMD test.txt 102400000 1
Dummy File Creator 1.2 Commandline Edition
Copyright c 2008 Nikko Cheng
Generating file: 100%
Total Data Written: 102,400,000 byte(s)
Time used: 2.34375 second(s)
Average Write Speed: 42,666 KB/sec


Batch File Format

Batch file list is a pure text file contain lines of following format:


So a typical batch list would contain lines similar like the following:
C:\Temp\Directory 1\1.txt	1024	0
C:\Temp\1.txt	0	0
C:\Temp\2.txt	1024	0
C:\Temp\3.txt	2048	1
C:\Temp\4.txt	1048576	1
Please note that RANDOM_SWITCH can only be a value of 0 or 1. Files will automatically be overwritten if exists.

Technical Facts

  • File Stream -
    Unlike previous version, Dummy File Creator 1.2 generates files in 4MB increment in order to increase performance of large file generation. To generate a 50MB file, Dummy File Creator will write 4MB data chunk 12 times and a 2MB chunk once to complete the task. In most cases, this behavior is unnoticeable. However, for people who would like to fill a disk drive with a larger-than-capacity dummy file. Dummy File Creator will try to fill the drive with closest size in 4MB increment. For example, if you are trying to fill a 50MB SD Card with a 1GB dummy file, Dummy File Creator will report an error and abort the operation after the size of generated file reaches 48MB, not 50MB as the software was unable to complete the writing task of the last 4MB data chunk. For data wiping purpose, this is already sufficient as all the of the available space was filled before the disk full error occurs; it is just that the last write operation attempt failed and resulted a size gap. Please keep this in mind if you are performing similar tasks.
  • Random Content -
    Dummy File Creator 1.2 writes random bytes ranging from 0 to 255. However, unlike previous version which generates true random file content, Dummy File Creator 1.2 uses a different approach in random content generation in order to increase the performance of random content generation. Dummy File Creator now will generate 4MB of random data and reuse the same data by altering only some bytes at random locations for each subsequent write. While the result still defeats all of the compression software we tested (i.e. a larger compressed file than the original size), but it is still possible to compress this pseudo-random content if a specifically designed compression algorithm targeted at Dummy File Creator (very unlikely) is used. To design such algorithm, it must use dictionary words with length ranging from 1 to 4,194,303 bytes. Most people will not notice this change, but for people who are developing compressing algorithms, it is recommended to use the previous version which generates true random contents (but much slower) for testing.
  • Compressible Content -
    Dummy File Creator 1.2 still writes ' ' (space character, Decial: 34, HEX: 20) as repeated content.
Previous verions

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