THE CHALLENGE OF 'HARVEST NOW, DECRYPT LATER' (HNDL) TO THE INTERNATIONAL LAW OF STATE RESPONSIBILITY IN THE QUANTUM ERA

Аннотация

The emergence of Cryptographically Relevant Quantum Computers (CRQCs) presents a profound challenge to the temporal and material thresholds of international law, specifically through the strategic practice known as "Harvest Now, Decrypt Later" (HNDL). This adversarial model, wherein state and non-state actors exfiltrate encrypted data with the intent of decrypting it once quantum capabilities mature, creates a legal grey zone that defies the traditional application of the International Law Commission’s Articles on Responsibility of States for Internationally Wrongful Acts (ARSIWA). This article investigates the compatibility of ARSIWA’s doctrines of attribution and breach with the delayed-impact nature of HNDL. Through a doctrinal legal analysis of recent scholarship and technical forecasts regarding Post-Quantum Cryptography (PQC), this study identifies a critical "attributional twilight" and a disconnect between the moment of data interception and the realization of injury. The results indicate that current legal frameworks treat HNDL largely as espionage—a practice often tolerated in international relations—thereby failing to account for the catastrophic, long-tail damage of retrospective decryption. The article concludes that the principle of due diligence must be radically reinterpreted to include a "crypto-agility mandate," obligating states to preemptively transition critical infrastructure to quantum-safe standards to fulfill their international responsibilities.