2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/216717A conjugate code pair is defined as a pair of linear codes such that one contains the dual of the other. The conjugate code pair represents the essential structure of the corresponding Calderbank-Shor-Steane (CSS) quantum code. It is argued that conjugate code pairs are applicable to quantum cryptography in order to motivate studies on conjugate code pairs.7 pages, no fugure. To appear in Tamagawa University Research ReviewQuantum Physicstext