Microsoft KB Archive/249780

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Article ID: 249780

Article Last Modified on 4/17/2006


  • Microsoft Outlook 2000 Standard Edition
  • Microsoft Exchange Server 5.5 Standard Edition

This article was previously published under Q249780


Microsoft Outlook 2000 Service Release 1 (SR-1) contains key advances in messaging security via support for Secure/Multipurpose Internet Mail Extensions version 3 (S/MIME v3).
S/MIME v3 is an Internet Engineering Task Force (IETF) Internet standard which extends the capabilities of S/MIME v2, most of which was implemented in Microsoft Outlook Express and Outlook 98.

The new Cryptographic Message Syntax standard, S/MIME v3 and S/MIME v3 Extended Security Services (ESS), taken together, allow S/MIME to provide greatly enhanced capabilities.


Some of the key features of Outlook 2000 SR-1 for advanced security are:

  • Support for the Diffie-Hellman Key Agreement for encryption
  • DSS for Digital Signature - an SHA hashing algorithm that generates a 160-bit hash value.
  • Signed (Secure) receipts
  • Security labels
  • A new Certificate User Interface
  • The ability to publish your S/MIME certificates to the Global Address List
  • Multiple layers of encryption and signatures
  • Multiple digital signatures per layer

Several new Outlook 2000 features are implemented, as well. These features are:

  • LDAP support in-the-box for accessing certificates
  • Cryptographic auto configuration to assist in setting up a security profile
  • Contact security properties to control encryption to external addresses
  • Ability to share contact entries which contain certificates
  • Addition of "Signed By" to Read Note form

NOTE: The enhanced encryption and security features of this release require Microsoft Windows 2000.

IMPORTANT: Outlook continues to work with Internet Explorer 4.x and Internet Explorer 5 without these new encryption and security features. There is no need to upgrade to a new operating system or a new version of Exchange Server unless you need these new features. (Note that the new security and encryption features are disabled but visible if Outlook 2000 SR-1 is installed without upgrading the operating system to Windows 2000.)

The advanced security features of Outlook 2000 SR-1 are enabled by the addition of a registry key. To enable these new features:

  1. WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

  2. Start Registry Editor (Regedt32.exe).
  3. Locate the following subkey in the registry:


  4. On the Edit menu, click New, and then click Key.
  5. Type Security to name the new subkey, and then select this new subkey.
  6. On the Edit menu, click Add Value, and then add the following registry value:

    Value Name: EnableSRFeatures Data Type: REG_DWORD Value: 1

  7. Quit Registry Editor.

If the EnableSRFeatures value is set to 0, the new security features are not enabled or visible to users.

Additional information about enhanced security features in Outlook 2000 SR-1 can be found in the New Encryption and Security Features in Microsoft Outlook 2000 SR-1 white paper. This white paper also documents additional registry settings that allow you to customize security. You can download the white paper from the following location:

For additional information about how to obtain SR-1, click the article number below to view the article in the Microsoft Knowledge Base:

245025 OFF2000:How to Obtain and Install Microsoft Office 2000 Service Release 1 (SR-1)


The Internet Engineering Task Force

RFC 2312: S/MIME Version 2 Certificate Handling

RFC 2311: S/MIME Version 2 Message Specification

RFC2632: S/MIME Version 3 Certificate Handling

RFC2633: S/MIME Version 3 Message Specification

RFC2634: Enhanced Security Services for S/MIME

RSA Labs


White Paper

The white paper entitled "Microsoft Outlook 2000 Service Release 1," contains all of the Outlook 2000 SR-1 security registry settings. It is available on the following Web site:

Additional query words: OL2K

Keywords: kbbug KB249780