IAMCertifiedOutputProtection::KeyExchange method (strmif.h)

Article
02/22/2024

[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The KeyExchange method returns the graphics driver's certificate.

Syntax

HRESULT KeyExchange(
  [out] GUID  *pRandom,
  [out] BYTE  **VarLenCertGH,
  [out] DWORD *pdwLengthCertGH
);

Parameters

[out] pRandom

Receives a 128-bit random number, generated by the graphics driver. Use this value in the IAMCertifiedOutputProtection::SessionSequenceStart method.

[out] VarLenCertGH

Receives a pointer to a buffer containing the graphics driver's certificate. The method allocates the memory for the buffer. The caller must release the memory by calling CoTaskMemFree.

[out] pdwLengthCertGH

Receives the length of the buffer returned in VarLenCertGH.

Return value

Returns an HRESULT value. Possible values include the following.

Return code	Description
S_OK	Success.
E_UNEXPECTED	Invalid state. Possibly the application passed unexpected data, or called IAMCertifiedOutputProtection methods in the wrong order. If this error occurs, the application should release the current instance of the VMR.
VFW_E_NO_COPP_HW	The display device does not support COPP; or the VMR has not connected to a display device yet.
ERROR_GRAPHICS_NO_MONITORS_CORRESPOND_TO_DISPLAY_DEVICE	No monitors correspond to the display device. This error can occur if the display mode changes; or the user turns off a monitor or removes a monitor.

Remarks

The graphics driver's certificate contains the driver's public encryption key.

If this method returns E_UNEXPECTED, the application should create a new COPP session by releasing the VMR, creating a new instance of the VMR, and calling KeyExchange again on the new instance.

Requirements

Requirement	Value
Minimum supported client	Windows XP with SP2 [desktop apps only]
Minimum supported server	Windows Server 2003 R2 [desktop apps only]
Target Platform	Windows
Header	strmif.h (include Dshow.h)
Library	Strmiids.lib