Antipiracy Measure Blocks OEM COAs

Activating other copies of Windows by using Certificates of Authenticity (COAs) from major OEMs will no longer be possible over the Internet. The measure is designed to prevent traffic in OEM COAs, which affix unique numbers to new computers to confirm that they have a legal copy of Windows installed. The measure, which went into effect Feb. 28, 2005, will affect COAs from the 20 largest OEMs, and in rare cases may have a minor impact on their customers.

An Antipiracy Move

The measure is designed to stop the theft or counterfeiting of COAs from OEM PCs.

Every COA contains a unique product key, and the product key is normally entered on a Windows XP installation screen during installation. A hashed value derived from the product key and from certain characteristics of the computer’s hardware is sent to Microsoft during activation of Windows XP. Since the introduction of Windows XP SP1, the product key itself is also sent during the activation process. (Because the hashed value sent during activation cannot be factored to reveal either the product key or any information about the user’s system, the product key must be sent as well to ensure that it is not used repeatedly.)