2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/118454A conjugate code pair is defined as a pair of linear codes either of which contains the dual of the other. A conjugate code pair represents the essential structure of the corresponding Calderbank-Shor-Steane (CSS) quantum code. It is known that conjugate code pairs are applicable to (quantum) cryptography. We give a construction method for efficiently decodable conjugate code pairs.Submitted to IEEE Trans. Information Theory (Aug. 2006). Ver.2: an obvious tiny error corrected (rate is k/n, not k)Quantum Physicstext