This Encryption Software for Windows is Freeware. 
It runs at least on Win 95/98/NT/2000/XP/2003 Server.
The Sourcecode is available.
But: How secure is Open Source Software (OSS)?
 

What does this program do? Read the PDF-File. (German, older version)

© 2001 Lasse Kolb

Download PDF-File
 

© 1996–2005 Markus Hahn

Want to know more about Cryptography and Computer Security?
If so, have a look at Counterpane (the origin of Blowfish).

One powerful file encryption and security tool for the Windows platform.
As the successor of highly successful BFA97, Blowfish Advanced CS offers a bunch
of new and improved features which are:

* Algorithms: Blowfish, Twofish, AES, RC4, Triple-DES, Serpent, CAST
* Strong key support, handling and cryptographic implementations
* Fast: encrypts megabytes of file data per second on modern machines
* Data compression using LZSS, ZIP's deflate and BZIP2
* Secure wiping of files and clearing of empty disk space
* Comfortable and efficient user interface with built-in file browser
* Easy working with encrypted files
* Complete integration into Windows Explorer via shell extension
* Automation of daily routines by using job files
* Dozens of options to finetune the application for different purposes
* Small: fits on half of the space of a floppy disk!
* Trustworthy: the complete source code is available for review
* Quick language switch, German and English are supported
* Runs on all Win32 versions, from Windows 95 to Windows Server 2003
* Personal Edition without any restrictions!

Die Benutzeroberfläche:
Verschlüsseln, Entschlüsseln, Wipen. (v.l.n.r.) übersichtlich nebeneinander.

Dateien verschlüsseln:
Auf Wunsch werden die Passwort-Hashwerte gesichert,
ebenso kann eine Keydisk verwendet werden oder der Schlüssel
wird in mehrere Teile zerlegt. Zusätzlich können Dateien
komprimiert und Dateinamen verschleiert werden.

Optionen:
Es stehen 8 Algorithmen und 3 Kompressions-Methoden zur Wahl,
ebenso 3 Wipe-Methoden. Das Programm kann umfangreich
konfiguriert werden.

Explorer-Extension:
Das Programm fügt sich nahtlos in den Windows-Explorer ein.

In diesem Beispiel: Version: 2.55

Blowfish Advanced CS 2.57 without Installer – Open Source

Download Blowfish Advanced CS Binaries (614 kB)
MD5: 65 ed 16 da b0 96 4f 9b d8 6b 62 bd 5a 00 ab d9

Blowfish Advanced CS 2.57 with Installer – Open Source

Download Blowfish Advanced CS Binaries (908 kB)
MD5: e1 40 82 3e ec 62 34 0f 1b 5f 3c b4 0e 63 ca 1f

Blowfish Advanced CS 2.57 Sourcecode – Open Source

Download Blowfish Advanced CS Sourcecode (1013 kB)
MD5: fb fb 6f 7e 5f 33 c8 60 42 e8 57 4f f3 72 22 99

MD5 Checksum 1.04 – Freeware

Download MD5 Checksum (46 kB)
MD5: 2b 63 92 0c bb d2 85 26 02 f0 90 5d 0e 2c 72 e7

Password Finder 1.0d – Freeware (old version)

Download Password Finder (102 kB)
MD5: cb 68 ae 08 d7 30 a4 88 1d f1 8c fb 70 18 af 18

Password Finder 2.01 – Freeware (new version)

Download Password Finder (49 kB)
MD5: ad 67 78 12 87 7b 51 76 a5 39 23 1c ed b4 a6 7c

Dummy Cryptfile Generator 1.2b – Freeware

Download Dummy Cryptfile Generator (227 kB)
MD5: 4e c1 84 dc a8 8a e7 c3 39 2f 7d 11 51 59 34 c8

BlowfishJ 2.15 – Open Source

Download BlowfishJ (46 kb)
MD5: 3f 57 62 48 34 dd c7 d1 63 e2 8f b5 0b 04 b8 39