Windows Code Signing Evolution

Windows Code Signing Evolution

Code signing on Windows has undergone significant changes over the years. In the early days, you could sign your applications with any certificate from a trusted certificate authority, and Windows would trust it. The process was relatively simple, but it had security limitations. Anyone with a valid certificate could sign code, and there was little verification of the developer's identity.

Microsoft introduced more rigorous requirements over time. The first major change was the requirement for code signing certificates to use hardware tokens, like USB dongles or smart cards, instead of storing the private key in a file. This made it much harder for attackers to steal signing keys. The next change was the introduction of extended validation (EV) code signing certificates, which required a more thorough verification of the developer's identity.

The most significant change came with SmartScreen and the reputation-based system. Even with a valid signature, if your application was new and had no reputation, Windows SmartScreen would show a warning to users. This made it harder for new developers to distribute their applications. The system was designed to protect users from unknown software, but it also created friction for legitimate developers just starting out.

Microsoft has continued to evolve the signing process. The latest changes include support for timestamping, which ensures that signatures remain valid even after the certificate expires. The introduction of the Windows Hardware Developer Center and the Partner Center streamlined the process of getting certificates. And most recently, Microsoft introduced Azure Trusted Signing, which eliminates the need for hardware tokens entirely by using cloud-based signing.