Using Security Features in Outlook

Encryption Strengths for Secure E-mail Messaging

There are two classes of encryption key strengths available from Microsoft: 128-bit Domestic Only and 40-bit International.

The following table summarizes the capabilities of Domestic Only encryption.

The following table summarizes the capabilities of International encryption.

Note   For signing, the Digital Signature Key lengths for Domestic and International encryption are RSA 1024-bit and RSA 512-bit, respectively.

Microsoft Office 2000 includes a technology that determines whether the user’s installation is capable of 128-bit Domestic encryption operations. Microsoft provides 128-bit encryption capabilities in Microsoft Internet Explorer 3.02, Internet Explorer 4.x, Internet Explorer Service Packs, Windows NT 4.0, and Windows NT 4.0 Service Packs. These are the programs that the Windows® installer tests for certified 128-bit encryption capabilities during Office 2000 Setup.

If your system already has 128-bit encryption capabilities, Office 2000 installs new 128-bit encryption components during Setup. Systems that do not already have 128-bit encryption capabilities receive 40-bit encryption components.

If 128-bit encryption capabilities are required, and if installation is allowed by US government restrictions, then the Outlook 2000 Domestic Security Pack installs 128-bit encryption components for Internet Explorer 4.x or later and Outlook 2000. The Domestic Security Pack is installed after the Office 2000 installation is completed.

Note   When users exchange e-mail messages internationally, Outlook uses the minimum encryption strength that is supported by the e-mail client application of both the sender and the recipient of the message.

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See also

You can upgrade to 128-bit encryption for Outlook 2000 by downloading the Outlook 2000 Domestic Security Patch. For more information, see the Outlook 2000 high encryption page on the Office Update Web site at http://officeupdate.microsoft.com/info/outlook2000highencrypt.htm.