# Tag Info

The only way I'd change it is to make it explicit that $k$ is sampled from that set rather than is equal to it and to note that the key is used cyclically: \begin{eqnarray*} \mathrm{Gen}:&&k\leftarrow \{0,\ldots,25\}^t\\ \mathrm{Enc}:&&c_i=p_i+k_{i\pmod t}\pmod{26}\\ \mathrm{Dec}:&&p_i=c_i-k_{i\pmod t}\pmod{26} \end{eqnarray*}