Signing quantum messages has been shown to be impossible even under computational assumptions. We show that this result can be circumvented by relying on verification keys that change with time or that are large quantum states. Correspondingly, we give two new approaches to sign quantum information. The first approach assumes quantum-secure one-way functions (QOWF) to obtain a time-dependent signature scheme where the algorithms take into account time. The keys are classical but the verification key needs to be continually updated. The second construction uses fixed quantum verification keys and achieves information-theoretic secure signatures against adversaries with bounded quantum memory i.e. in the bounded quantum storage model. Furthermore, we apply our time-dependent signatures to authenticate keys in quantum public key encryption schemes and achieve indistinguishability under chosen quantum key and ciphertext attack (qCKCA).

翻译：签署量子消息已被证明即使在计算假设下也是不可能的。我们表明，通过依赖于随时间变化的验证密钥或作为大规模量子态的验证密钥，可以规避这一结果。相应地，我们提出了两种签署量子信息的新方法。第一种方法假设量子安全单向函数（QOWF），从而获得一个时间相关的签名方案，其中算法将时间因素纳入考虑。密钥是经典的，但验证密钥需要持续更新。第二种构造使用固定的量子验证密钥，并在对抗具有有界量子存储的敌手时（即有界量子存储模型）实现信息论安全的签名。此外，我们将时间相关签名应用于量子公钥加密方案中的密钥认证，实现了在选择的量子密钥和密文攻击（qCKCA）下的不可区分性。