Microsoft Security Advisory 3045755: Update to improve PKU2U authentication

Applies to: Windows Server 2012 R2 DatacenterWindows Server 2012 R2 StandardWindows Server 2012 R2 Essentials


Microsoft is announcing the availability of a defense-in-depth update that improves the authentication that is used by the Public Key Cryptography User-to-User (PKU2U) security support provider (SSP) in Windows 8.1, Windows Server 2012 R2, and Windows RT 8.1. The improvement is part of ongoing efforts to strengthen the effectiveness of security controls in Windows.


Microsoft has released a Microsoft security advisory about this issue for IT professionals. The security advisory contains additional security-related information. To view the security advisory, visit the following Microsoft website:
The following files are available for download from the Microsoft Download Center:

For all supported x86-based versions of Windows 8.1

Download Download the package now.

For all supported x64-based versions of Windows 8.1

Download Download the package now.

For all supported x64-based versions of Windows Server 2012 R2

Download Download the package now.

Release Date: April 14, 2015

For more information about how to download Microsoft support files, click the following article number to view the article in the Microsoft Knowledge Base:
119591 How to obtain Microsoft support files from online services
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File information

The English (United States) version of this software update installs files that have the attributes that are listed in the following tables. The dates and times for these files are listed in Coordinated Universal Time (UTC). The dates and times for these files on your local computer are displayed in your local time and with your current daylight saving time (DST) bias. Additionally, the dates and times may change when you perform certain operations on the files.