The draft APIs will be available to security vendors for testing and comment through the end of January. A final version of the APIs will then become available when Microsoft releases Service Pack 1 for Vista sometime in mid-2007, according to Ben Fathi, vice president of development for the Windows Core Operating System.

Microsoft Tuesday also released a separate Criteria Evaluation document that details the processes Microsoft used in evaluating vendor requests for APIs to the Vista kernel. As with the draft APIs, Microsoft is seeking third-party security vendor feedback on its criteria evaluation processes.

"We are publishing this to be very clear and above board on what our processes are for establishing the new APIs that we are going to add to the kernel," Fathi said. "We want to hear feedback from partners and the rest of the industry on whether this is a good set of criteria or not."

The APIs and the criteria evaluation document are part of Microsoft's response to widespread concerns within the security industry and the European Union (EU) over PatchGuard, Fathi said.

Microsoft itself has said the kernel patch protection technology is vital to ensuring the security and stability of the 64-bit Vista operating system because it prevents unauthorized modifications to the kernel -- both by security vendors and malicious attackers. The technology is especially key in protecting against problems such as rootkits, the company has said.