VLX file security

[mmawad]

Hello every one,

I'am not trying to hack a compiled routine, but should I trust the compiled vlx file "by vlide new application wizard" as I want to distribute some lisp routine that will contain some confidential information "mostly logic operations" and I'm sure that some with programming background will be eager find it out.

So I've done my research and found a tool to convert vlx back to fas, then another tool to decrypt that fas file, and a tool to disassemble the fas file.

I'm attaching a simple lisp routine, its compiled vlx, the decrypted fas file, and the disassembly text file. As I does not understand what had happened.

PLEASE NOTE that the decryption process for the fas file took almost a day

[cadffm]

Is it just an information or do you have a question?

[mmawad]

i'm asking if the fas file security have been compromised ?

[doaiena]

This isn't anything new. The level of secutity has remained the same for more than 15 years. If someone has the skill to completely reverse engineer your super secret algorithm from a vlx, they could write it on their own from scratch.

[hak_vz · Accepted solution]

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@mmawad wrote:

Hello every one,
PLEASE NOTE that the decryption process for the fas file took almost a day

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Almost every encrypted file can be decrypted.

If you think that your data and your project will intrigue someone to break the code then don't do it at all or find the way to make it hardly readable even when decrypted.

In professionally  written applications that I had a chance to work with,  code is divided in many small files that are all encrypted and distributors don't bother if someone will try to break it.

[cadffm]

"i'm asking if the fas file security have been compromised"

Not more or less then all the time.

The answer to this question you have to answer yourself.

Look at the result and then decide if it is acceptable to you or not. But in all respects, mathematical functions? Respect if you have to protect them because they are unknown to the rest of the world.

Try that: Take some few bucks and go to an onlone freelancer portal gor programmers.

Result should be a well working program (instead of decrypted fragments).

[john.uhden · Accepted solution]

This has been discussed before.  I don't think there is any way to decompile or reverse engineer a .VLX or .FAS file.  The only things that can be exposed (extracted) are embedded textual files including DCL.

[john.uhden · Accepted solution]

As a follow-up, while the code is not decryptable, your functions will be exposed after running if you don't localize them.

For example:

(defun c:Gizmo ( / *error* this that etc)

  (defun *error* ...)

  (defun this (input / output) ...)

  (defun that (input / output) ...)

  (defun other (input) ...)

  (princ)

)

See that the functions this and that are local, but other will remain after Gizmo is run and its name will show up in (atoms-family).  So you could, without localizing, allow your functions to be used by others.  But even then, don't overtrepidate unless you have used defun-q.