The CMSG_CTRL_DEL_SIGNER_UNAUTH_ATTR_PARA structure is used when deleting an unauthenticated attribute from a signer of a signed message. This structure is passed to CryptMsgControl for a value of CMSG_CTRL_DEL_SIGNER_UNAUTH_ATTR in dwCtrlType.
typedef struct _CMSG_CTRL_DEL_SIGNER_UNAUTH_ATTR_PARA {
DWORD cbSize;
DWORD dwSignerIndex;
DWORD dwUnauthAttrIndex;
} CMSG_CTRL_DEL_SIGNER_UNAUTH_ATTR_PARA, *PCMSG_CTRL_DEL_SIGNER_UNAUTH_ATTR_PARA;