2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/92729The model of the quantum protocols sealing a classical bit is studied. It is shown that there exist upper bounds on its security. For any protocol where the bit can be read correctly with the probability $α$, and reading the bit can be detected with the probability $β$, the upper bounds are $% β\leqslant 1/2$ and $α+β\leqslant 9/8$.5 pages, 1 figure. Add an example on how to break the majority voting schemeQuantum Physicstext