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IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:
256986 Description of the Microsoft Windows Registry
When you attempt to import a digital certificate into Internet Explorer from another browser, you may receive the following error message:
Internet Explorer was unable to import this certificate.
This error message can occur if you are attempting to import a 1024-bit key (high grade) or greater digital certificate, and you are not running the 128-bit version of Internet Explorer.
To resolve this behavior, upgrade to the 128-bit version of Internet Explorer. To obtain the 128-bit Internet Explorer Upgrade, please visit the following Microsoft Web site:
The 128-bit Internet Explorer Upgrade installs the Rivest-Shamir-Adleman (RSA) certificate provider. With the RSA certificate provider, you can import high grade digital certificates into Internet Explorer in PFX format.
You can import only 512-bit key (low grade) digital certificates into Internet Explorer.
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.
Note that this behavior can also occur if a previously exported 1024-bit key (high-grade) is improperly imported into a different system.
When this occurs, the 128-bit Cryptographic Service Provider (CSP) is not registered as the default provider. When you try to import the 1024-bit certificate onto a 1024-bit system, it does not work because it is trying to make a call to the default 512-bit base (exportable) provider, which does not accept strong cryptographic key sizes (>512 bit).
To correct this problem, change the following registry key: