program cloning

[opethon]

i have a custom made program that is being used to create layouts for harnesses assembly
the program is too old obsolete if i may say and the company refuses to renew or replace with auto cad anyway
the problem is files created by such program cannot be opened in auto cad or by any other similar program i even opened the output by notepad but seems like it has been encoded or encrypted in a way or so.
so is there any method to pinpoint where exactly this encryption happens in the assembly code of the program so that i can reverse it and understand the file content for further development ?
i just need to understand the data structure of the files created by such program to create a tool that can share the same output of the original file.

[Salem]

To check whether it is encrypted or not, a simple test is to see if you can compress the file. If you can, then it is almost certainly not encrypted (not by anything good at any rate)

Second, some tools
http://clusty.com/search?query=hex+editor&sourceid=Mozilla-search
http://clusty.com/search?query=binary+diff&sourceid=Mozilla-search
Notepad is useless for looking at binary files.

Third, the process.
Start small, with really simple files.
- Save the same file twice, separated by say 1 minute. If the resulting files are different, then the difference is probably encoding date/time information.
- then it's an incremental approach to modifying and comparing (you said CAD, so try adding a single line).

Once you know a few things, you can start guessing at what other things are for. Use the hex editor to make those changes and re-load the file into the application. Does it understand the change or just crash?

[opethon]

To check whether it is encrypted or not, a simple test is to see if you can compress the file. If you can, then it is almost certainly not encrypted (not by anything good at any rate)

Second, some tools
http://clusty.com/search?query=hex+editor&sourceid=Mozilla-search
http://clusty.com/search?query=binary+diff&sourceid=Mozilla-search
Notepad is useless for looking at binary files.

Third, the process.
Start small, with really simple files.
- Save the same file twice, separated by say 1 minute. If the resulting files are different, then the difference is probably encoding date/time information.
- then it's an incremental approach to modifying and comparing (you said CAD, so try adding a single line).

Once you know a few things, you can start guessing at what other things are for. Use the hex editor to make those changes and re-load the file into the application. Does it understand the change or just crash?

Salem i just want to thank u for the quick reply and i really appreciate ur help .
about the 1st part yes it has been confirmed according to the given test that the file isnt encrypted
the 2nd part i downloaded the hex workshop tool and successfully opened the file , vast difference between this hex tool and the notepad i agree but still the characters are a bit gloomy to understand i'll try it on a much simpler file and give u a feed back asap.