2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/91167We study the potential of general quantum operations, Trace-Preserving Completely-Positive Maps (TPCPs), as encoding and decoding mechanisms in quantum authentication protocols. The study shows that these general operations do not offer significant advantage over unitary encodings. We also propose a practical authentication protocol based on the use of two successive unitary encodings.LaTeX, 11 pagesQuantum Physicstext