ctx2        C.GO_HMAC_CTX
	size        int
	blockSize   int
	key         []byte
	sum         []byte
	needCleanup bool
}

func (h *boringHMAC) Reset() {
	if h.needCleanup {
		C._goboringcrypto_HMAC_CTX_cleanup(&h.ctx)
	} else {
		h.needCleanup = true
		// Note: Because of the finalizer, any time h.ctx is passed to cgo,
		// that call must be followed by a call to runtime.KeepAlive(h),