Visual FOXPRO Load/Use .FLL Files

Question

My company have an old application (from around 2005/2006) using Visual FoxPro 7 which sadly they don't have the source code (.PJX , .PJT) files. I have to change the connection string because we have to move the database to new server. The problem is the connection string in (connection.dbf file) is encrypted.

I've opened the .exe file with a text editor and found the following code

SET LIBRARY TO libs\Cipher50.fll ADDITIVE

Cipher50.fll exists in the root application folder.

My Question

I want to make an application that can load the "Cipher50.fll" file (maybe like .NET Reflection) and use the correct function so I can update my connection.dbf file.

How can I achieve this?

PS: I know nothing in Visual FoxPro.

I just want to point out that the PJX/PJT is really just a catalog of the project. The source is in PRG, SCX/SCT, VCX/VCT, MNX/MNT, FRX/FRT, etc. files. — Tamar E. Granor

Alan B Alan B · Accepted Answer · 2015-09-08T07:11:12

An FLL is basically a Windows DLL that contains calls to the Visual FoxPro API. They tend to be written in C or C++, so .NET is not a factor.

CIPHER50 in particular was developed by Tom Rettig and the C source is here. A Visual FoxPro implementation is here. You would basically have to figure out what encryption the above use, and if it can be reverse engineered.

Visual FOXPRO Load/Use .FLL Files

1 Answers