typedef struct _CM_KEY_SECURITY
{
     WORD Signature;
     WORD Reserved;
     ULONG Flink;
     ULONG Blink;
     ULONG ReferenceCount;
     ULONG DescriptorLength;
     SECURITY_DESCRIPTOR_RELATIVE Descriptor;
} CM_KEY_SECURITY, *PCM_KEY_SECURITY;

Windows Vista Kernel Structures