Digital Certificate Security

I digitally sign every executable with my certificate

I sign every program installation package available for download on this site with my personal digital certificate. The same is true for every executable file inside of the package. What does this mean, and more specially, what does it mean for you?

To start with, the first thing you see on Windows when running a executable that is not digitally signed is a yellow dialog with a warning. It tells you that the origin of the file is unknown. Thus, it can potentially be dangerous for your computer to run this file.

When you run a digitally signed executable file, the first thing you will see is a blue dialog window. It gives you information about who published the file and asks if you trust the publisher? But that is really just surface stuff and candy for the Graphical User Interface experience.

What a digital certificate really does

The certificates makes a statement that the file hasn’t changed since it was signed. Because, if the file were changed, e.g. by a virus, this would break the file’s encrypted signature. As a consequence, the file would not execute and run properly. As a result, the certificate would not be intact to display or even be available when you open the Properties dialog of the file. Even if the file somehow was enabled to run, you would know its been tampered with as Windows would give you the yellow dialog with a warning.

In practice it means that nobody can download any Astrocalc Software, change or repack it and then offer it with a claim it’s genuine software from Astrocalc or from me. So when you run my software and get the blue dialog you will know that the file is OK. Thus, it doesn’t impose any threat to your computer. You can also right click the file and open the properties dialog where you can display the certificate.

What does the certificate expire mean?

Also important to know; while a certificate has an expiry date that doesn’t mean the signed file turns bad/unprotected after this date. The expiration date merely means that’s the last date it’s valid to sign a file with. The signed file as such has no expiration.

And lastly…