December 2021 - Uwe Gradenegger

Requesting certificates with elliptic curve based keys fails when using Microsoft Platform Crypto Provider

Assume the following scenario:

A certificate template is configured to elliptic curves based keys to be used.
In addition, the certificate template is configured to use the Microsoft Platform Crypto Provider to use the private key with the Trusted Platform Module (TPM) of the device.
The certificate request fails with the following error message:

Error: The requested operation is not supported. 0x80090029 (-2146893783 NTE_NOT_SUPPORTED)

On Windows Server 2016, the error message "No provider was specified for the store or object. 0x80092006 (-2146885626 CRYPT_E_NO_PROVIDER)" is issued with otherwise identical behavior.

Basics: Elliptic curves with regard to their use in the public key infrastructure

With Windows Vista and Windows Server 2008, the Cryptography API: Next Generation (CNG) was introduced into the Windows systems.

This term refers to a collection of modern cryptographic functions. Among other things, the CNG enables the use of certificates that use keys based on elliptic curves (also called Elliptic Curve Cryptography, ECC) with the Microsoft Certification Authority and the Windows operating system.

Microsoft Outlook: Signed e-mail messages are rejected by the receiving mail server with error message "Invalid S/MIME encrypted message."

Assume the following scenario:

A user sends an e-mail message signed with Secure/Multipurpose Internet Mail Extensions (S/MIME).
The sender uses Microsoft Outlook for Macintosh.
The receiving mail server rejects the message and sends back a Non-Delivery Report (NDR):

550 5.6.0 M2MCVT.StorageError.Exception: ConversionFailedException - , Content conversion: Invalid S/MIME encrypted message.; storage error in content conversion.