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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

 
GeneralRe: Hello... A request... Pin
Nir Dremer13-Dec-02 0:02
memberNir Dremer13-Dec-02 0:02 
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 
While it is already pretty pointless (did you read the other posts in this thread?), let me answer some of your points:

nicthiessen wrote:
So basically you're saying run NT or forget having secure communications and files? So now you've limited yourself to share encrypted data with someone one NT or above AND they have to be in your active directory. What about the other 5billion people in the world?

As I mentioned already in another thread, we are talking here about Windows (remember, codeproject is a Windows site?). Now, how many of your "5billion" are using Windows? Fine. These few people still have to
a) use this utility (or a ported version to another OS)
b) transmit the password for the encryption to the recipient
While (a) might be possible, (b) causes a major headache for 99.9% of these 5 billions because they would just send the file together with the password in a mail. Bingo.

nicthiessen wrote:
Acutally, the EFS is using the DESX algorithm plus RSA public/private keys. So you've selected an encrytption system that is just as vulnerable to linear and differentials attacks as standard DES with slightly higher brute force key attack strength. Not even close to BlowFish, not even as good as DES3.

Simply wrong. EFS can use any of the installed CSP's. DESX, 3DES, AES, whatever you like as long as you have got a CSP for it.

nicthiessen wrote:
You need do some research into encryption first dude. Security through obscurity never works.

Been there, done that. None of the security features of Windows (NT/2k/XP/2003) is a secret (almost). The CSP's are publicly available information. Many 3rd party CSP's exist long time (wrote one myself), although some of questionable quality. The only obscurity here are developers without a clue, trying to "use" encryption without even knowing what it is supposed to do.

nicthiessen wrote:
Hmm, well from what i've read on Sysinternals (you should check it out) this "failsafe" recovery mechanisms can be used to fairly easily defeat the system.

So far there havent been any concerns on the key recovery as far as I know. Although I didnt find any information which points towards a flaw in this mechanism, you still have the option of NOT enabling the key recovery.
Then even you are on the safe side.


Leon[^] - Enterprise Anti-Spam Server
GeneralRe: Is EFS not good enough? Pin
supersuper2-May-04 7:08
membersupersuper2-May-04 7:08 
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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