Digital Signatures

Since May 2006, all King Stairs Software products (applications and installers) are digitally signed.

What is a Digital Signature?

Briefly, a digital signature is a block of information added to a file which identifies who signed that file, when it was signed, and also includes data to verify that the file has not been modified in any way since it was signed.

What are the Benefits of a Digital Signature?

The top benefits of digitally signed files:

1. Authenticity: The digital signature identifies the file’s origin, even if it has been renamed. This is valuable when you are downloading an application from a website and you’re not 100% sure of the file’s provenance.
2. Integrity: After a file is signed, if it is modified in any way the signature will no longer be valid. An invalid signature may indicate that the file was not downloaded correctly, or the file may be compromised by a virus or other malware. A digital signature provides another layer of protection.
3. Permission: In some environments, especially corporate, you may not be allowed to download or install unsigned applications. Furthermore, future versions of Windows are likely to require that applications be signed.

Identifying Digitally Signed Files

Current versions of Windows (Since XP) by default will check applications for digital signatures. The following two screenshots show the different dialogs that can be displayed when launching an unsigned application and a signed application:

With the signed application, the dialog confirms that it was signed by King Stairs Software. Clicking on the Publisher link brings up another dialog with more detais about the digital signature:

Finally, you can check any file for a digital signature by looking at its properties in Windows Explorer: A signed file displays an additional “Digital Signatures” tab in the Properties dialog:

(FYI These screenshots were taken on Windows XP, but the dialogs are almost identical on Vista and Windows 7).