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File Encryption Utility

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4.70 (21 votes)
22 Sep 2002GPL3
File Encryption Utility based on Blowfish Encryption Algorithm.

Sample Image - FileEncryption.jpg

Introduction<o:p>

After a long search for a simple and secure file encryption utility, that is simple and intuitive to use I've decided to write something of my own.<o:p>

File Encryption utility is a simple tool for encrypting both text and binary files using the blowfish encryption algorithm.<o:p>

The utility can create a self extracting encrypted file. For a deep view of how to create a self extracted executable check my other article: Creating Self-Extracted Executable .<o:p>

Features<o:p>

File Encryption Utility Has the following features:<o:p>

  • Fast & Quick File Encryption/Decryption.<o:p>
  • Internal File Wiping Utility.<o:p>
  • Creating Self-Extracting Encrypted File.<o:p>
  • Explorer Integration (through Configuration Dialog).<o:p>
  • Command Line Parameters.<o:p>

Language<o:p>

The File Encryption utility is writen in native C++ using ATL only for windowing classing.<o:p>

The usage of ATL is minimal so anyone who is not familiar with the library should be able to understand the code as well.<o:p>

Overview<o:p>

File Encryption Utility is divided to few small projects:<o:p>

  • FileEnc – The UI of the file encryption utility, also containing the Processing class which is also used by SelfExtract and it is responsible for reading/writing files.<o:p>
  • Enc_Blowfish – Blowfish encryption implementation (based upon Bruce Schneier and Jim Conger implementation).<o:p>
  • SelfExtract – Self Extracting executable "header".<o:p>
  • GenLib – Small Library holding all commonly used items in other project parts.<o:p>
  • Builder – Small Console utility for creating the final File Encryption Executable.<o:p>

GenLib – The General Library<o:p>

In order to save time and to have a central point for all general purpose classes I'm working with a static library called GenLib.<o:p>

A stripped version of the GenLib is available with the File Encryption Utility. In this version you can see the following general purpose classes:<o:p>

  • GenFiles – Openning OpenFile/SaveFile and OpenDirectory Dialog Boxes.<o:p>
  • SelfExtract – Creating Self-Extracting Executable.<o:p>
  • Thread – Implementation of a parent class for classes who want to execute code in separate thread (more information can be seen in the header – thread.h).<o:p>
  • FileWipe – Wiping a File from Hard Drive.<o:p>

All those classes are under the GenLib namespace.<o:p>

Additional Encryptions<o:p>

Inside the FileEnc project there's an interface called EncryptionInterface – implementing this interface can allow you to easily change the encryption the utility uses.<o:p>

Implementing this interface requires only stream cipher implementation and saves all the overhead of working with files.<o:p>

Blowfish implementation is statically linked to the utility in order to avoid hacking by changing the dll. With a few minutes of work the utility can support a number of encryption dlls that can be loaded at runtime based on the users decision.<o:p>

Security<o:p>

In order to make the utility the most secure I can I've tried wiping information from memory when the application closes.<o:p>

When looking at the source, you can see that I've used ZeroMemory API and few others APIs to delete information from memory (like the password used).<o:p>

When encrypting a file you can mark the 'Wipe Source After Process' checkbox and by that insure that the file you're encrypting is not accessible.<o:p>

Remarks<o:p>

Decryption does NOT verify password correctness (information is being encrypted without adding any information about the file). As a result when decrypting with the wrong password you will receive a file with junk inside - this is not a bug.<o:p>

The file encryption is based upon the password length - larger passwords equal better security.<o:p>

Although I believe that the file wiping method is very secure, to be 100% sure you should use a product dedicated to that purpose.<o:p>

Reference<o:p>

Blowfish encryption algorithm - http://www.schneier.com/paper-blowfish-fse.html

Revision History

23 Sep 2002 - Initial Revision

License

This article, along with any associated source code and files, is licensed under The GNU General Public License (GPLv3)

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About the Author

Nir Dremer
Product Manager
Israel Israel
Nir is a Product Manager from Israel with past Software Engineering Experience.

You're welcome to visit his photography site:
http://www.dremer.net/

Comments and Discussions

 
QuestionIs EFS not good enough? Pin
Andreas Saurwein Franci Gonçalves24-Sep-02 23:31
memberAndreas Saurwein Franci Gonçalves24-Sep-02 23:31 
AnswerRe: Is EFS not good enough? Pin
Nir Dremer25-Sep-02 0:08
memberNir Dremer25-Sep-02 0:08 
GeneralRe: Is EFS not good enough? Pin
Andreas Saurwein Franci Gonçalves11-Dec-02 6:10
memberAndreas Saurwein Franci Gonçalves11-Dec-02 6:10 
GeneralRe: Is EFS not good enough? Pin
Nir Dremer13-Dec-02 0:15
memberNir Dremer13-Dec-02 0:15 
GeneralRe: Is EFS not good enough? Pin
Andreas Saurwein Franci Gonçalves13-Dec-02 4:11
memberAndreas Saurwein Franci Gonçalves13-Dec-02 4:11 
GeneralRe: Is EFS not good enough? Pin
supersuper26-Apr-04 10:27
membersupersuper26-Apr-04 10:27 
GeneralRe: Is EFS not good enough? Pin
Andreas Saurwein Franci Gonçalves26-Apr-04 11:49
memberAndreas Saurwein Franci Gonçalves26-Apr-04 11:49 
GeneralRe: Is EFS not good enough? Pin
supersuper2-May-04 7:08
membersupersuper2-May-04 7:08 
Maybe you can clarify this for me, but it seems that EFS and the file encryption utility are meant for different applications. Where efs is aimed mainly at protecting your own files on your own pc or on your network shares, it is not designed for sharing encrypted data with people outside of you windows network. ie. the windows user on company B's network won't have the keys to decrypt the file since their identity couldn't have been added to the key list, so you can't send them an encrypted file.

However this utility was designed to be able to share encrypted data with other contacts outside of your network. All you need is a password. Obviously you'll need to ensure the password is sent safely, not open text in an email, but EFS has exactly the same problem. But now you're not limited to access lists, and you can have separate passwords for every file. My understanding of EFS is once you gain access to someones PC with their login you now have full access to all of their encrypted data.

Maybe you like EFS, that's fine. I don't see a lot of merit in it, but then i have nothing to hide within the company that i work for.

My need was to send an encrypted file via email, efs couldn't do it (i tried, the user didn't exist on the access list, couldn't add him), this app could.

On the side, i'll take your word about the addition of CSP's, but doesn't that then reduce the usefullness since everyone you share with has to have that CSP now? Although i suppose since you're all on the same network it would be easy to transfer. Still that's another of the nice features of this utility, it can make a self extracting file. That's pretty slick, all you need is the right password, and the password isn't stored in the file so it's a strong as the encryption technology.

i'm not trying to bash you, i apologize if i came off that way.

nic
AnswerRe: Is EFS not good enough? Pin
Anonymous1-Mar-04 0:33
memberAnonymous1-Mar-04 0:33 
GeneralRe: Is EFS not good enough? Pin
Andreas Saurwein Franci Gonçalves1-Mar-04 4:21
memberAndreas Saurwein Franci Gonçalves1-Mar-04 4:21 
GeneralBlowfish vs Twofish Pin
Anonymous23-Sep-02 12:06
memberAnonymous23-Sep-02 12:06 
GeneralRe: Blowfish vs Twofish Pin
Nir Dremer23-Sep-02 22:15
memberNir Dremer23-Sep-02 22:15 

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Posted 19 Sep 2002

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