Windows now enforces the use of the Cryptography Next Generation (CNG) Key Storage Provider (KSP) by default for RSA operations.

Cryptographic Service Provider (CSP) for RSA-based smart card operations. While this improves security, it caused many legacy 32-bit applications and smart card drivers to fail. Temporary Workaround If your applications can no longer access smart card private keys (often resulting in "Invalid provider type specified" errors), you can manually set a registry override to re-enable legacy CAPI/CSP behavior: Registry Path: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Cryptography\Calais Value Name: DisableCapiOverrideForRSA Type: REG_DWORD Value Data: 0 (This disables the "override" and reverts to legacy behavior) 11 sites DisableCapiOverrideForRSA registry removal impact on ... Mar 26, 2026 —

In October 2025, Microsoft released security updates (such as and KB5066782 ) aimed at addressing vulnerabilities like CVE-2024-30098 . These updates changed how Windows handles RSA-based smart card certificates.

— Some VPN, disk encryption, or DRM software may have an undocumented debug flag controlling whether to override default RSA handling in their cryptographic service provider.

Disabling the override is generally discouraged unless strictly necessary. By forcing the system back to legacy CAPI, you opt out of the performance improvements and side-channel attack protections built into the CNG architecture. It is a classic trade-off: