Protecting Sequence Files From Modifications

[OmarGator]

I sure others have had to do this in the past.

What is the best way to protect the sequence file from being modified in the field?

Even I, with my limited TestStand skills, have gone in with a text editor and changed things in a sequence file.

We would like to encrypt the sequence file and then have code to convert it back as it is loaded.

Or is there a better way.

We are also encrypting the report files on the back end so those can't be altered easily.

Thanks

[GuenterMueller]

Encryption is an excellent way.
Another option would be to download your SeqFile from a database just before starting up the tester. If you already have a database, this is quickly done.
Regards, Guenter.

[OmarGator]

We have used a database and also a protected directory on a network server to protect the sequence files. But I had control over both the data base and the network server.

This is going to a third party contract manufacture oversea and we do not have access or control over a data base or network directory.

We need to prevent the contract manufacture from "tweaking" limits or tests without our knowledge. We could hard code the limits in our LV code, but that defeats the need for TestStand.

So we feel that encryption is our only way, just not sure where to insert the code to un-encrypt the sequence file to hand off to TestStand.

Thanks

[GuenterMueller]

Hi Omar,
how to load a Client Sequence File dynamically is discussed here.
Your process model could call an executable that executes the decryption in advance. This is not very graceful. But as long as you have the decryption password in the executable your Client Sequence Files are quite safe.
Maybe you refine this idea?
Regards, Guenter

[Dennis_Knutson]

What version of TestStand are you using? According to this version 3.5 has some built-in security features.

If you don't want to or can't upgrade, there are a few other things I can think of. Are you getting copies of the test results from the CM. At each of the CMs I deal with, we insist on an Internet connection so that the test results are transfered to our local database. If I wanted, I could look at the limits and number of test in the results and compare to a master. I also install VNC on each of the deployed testers. This not only helps to debug when a problem arises, but I can do a simple check sum on the sequence file and compare it to my local copy.

[Patrick_P.]

Hi Omar,

As Dennis mentioned in his previous post, with TestStand 3.5 there is an option to lock sequence files.  When you lock the sequence file, it encrypts the sequencefile in a binary format to prevent editing.  You can't edit it from the sequence editor unless you have the password to unlock the file.  This doesn't completely protect the file because someone could open the file and still modify the binary, but if they modify it, TestStand should say the file can't be opened.  Hope this helps!