Beispiel zum Erstellen eines Sitzungsschlüssels

Der Sitzungsschlüssel wird verwendet, um den Inhaltsschlüssel zu schützen. Der folgende Code veranschaulicht das Erstellen eines Sitzungsschlüssels, lässt jedoch die Details der zufälligen Schlüsselgenerierung aus.

HRESULT CreateSessionKey( WMDRM_IMPORT_SESSION_KEY **ppSessionKey, DWORD *pcbSessionKey )
{
    // TODO: Set this value to the desired number of bytes for the session key data. 
    const DWORD SESSION_KEY_DATA_SIZE = 20; 

    HRESULT hr = S_OK;
    WMDRM_IMPORT_SESSION_KEY *pSessionKey = NULL;

    if( NULL == ppSessionKey )
    {
        hr = E_POINTER;
        goto EXIT;
    }
    
    // Compute the size of the session key structure plus the session key.
    DWORD cbSessionKey = sizeof( WMDRM_IMPORT_SESSION_KEY ) + SESSION_KEY_DATA_SIZE;

    // Allocate memory for the session key.
    pSessionKey = (WMDRM_IMPORT_SESSION_KEY *)new BYTE[ cbSessionKey ];
    if( NULL == pSessionKey )
    {
        hr = E_OUTOFMEMORY;
        goto EXIT;
    }
    ZeroMemory( pSessionKey, cbSessionKey );

    // Set the key type and the key size.
    pSessionKey->dwKeyType = WMDRM_KEYTYPE_RC4;
    pSessionKey->cbKey = SESSION_KEY_DATA_SIZE;
    
    // Set the key to a random value. Note that the random number
    //  generator is not very good. It is only intended to be demonstrative
    //  and it is not recommended for use in shipping code.
    srand((unsigned int)time(NULL));
    BYTE* pKeyData = pSessionKey->rgbKey;
    for (size_t i = 0; i < SESSION_KEY_DATA_SIZE; ++i)
    {
        *pKeyData++ = (BYTE)(rand() & 0xFF); 
    }
    
    // If all has been successful set the parameters.
    *ppSessionKey = pSessionKey;
    pSessionKey = NULL;
    *pcbSessionKey = cbSessionKey;

EXIT:
    
    SAFE_ARRAY_DELETE( pSessionKey );
    return hr;
}

Zugehörige Themen

DRM-Importbeispiele