Digital Signature

I purchased a Code Signing Certificate from Certificate Authority (CA) company Sectigo and used it to digitally sign (and timestamp) program executable files and install programs. This attaches a cryptographic signature to the file that can only be created by my registered certificate, in combination with both the Microsoft certificate and the Sectigo certificate.

When the program is run, Windows checks the attached encrypted signature that indicates the code has not been altered. Code Signing proves that the program actually came from me and has not been modified by a hacker since it was signed. If even a single byte is changed, either in the file or in the signature, the signature will show as invalid in the file properties.

The signature says it was signed by MICHAEL ROBINSON and has a date and time stamp certified by the Sectigo time stamp server.

To check the signature, run Windows File Explorer (explorer.exe) right click on the file and select Properties:

Then click on the tab Digital Signatures, and click the Details button:

Then click the View Certificate button to see my certificate:

Invalid Signature Samples

Do not run the program is you see one of these in File Properties. It means the program has been modified or corrupted.

I changed one byte near the start of the program and got this:

I changed one byte near the end of the program and got this:

I changed one byte at the very end of the program and got this:

There must be similar messages for other defects.