# Where are labels of a Labeled data used in homomorphic message authenticator stored?

In a fully homomorphic message authenticator, Alice can authenticate some large data $$D$$ using her secret key $$s$$k. She chooses a label $$\tau$$ for it, and the authentication algorithm authenticates the data $$D$$ with respect to the label $$\tau$$.

But, how and where are these labels stored?

• See the Syntax part of the article. You send $\sigma$ as the authenticator of the bit and after eval, Verify uses the bit $e$, program $P$ and the tag of the evaluation $\psi$ – kelalaka Nov 19 '19 at 12:06
• @kelalaka They generate $\nu = f_{k}(\tau )$ . Then, output $\sigma= (c_1, . . . , c_n , \nu )$. How is $\nu$ stored ? – safyg Nov 19 '19 at 17:41