Steganography conceals secret information within innocuous carriers while preserving visual fidelity and enabling reliable recovery. Recent unified networks operate normally under untriggered conditions but switch to hidden steganographic tasks when triggered. PUSNet follows this paradigm by performing image purification during normal operation and steganographic embedding when activated. However, it supports only a single user with one key pair, limiting its applicability in multi-user settings. We propose PUSNet-MK, a multi-key extension that enforces strict key isolation via a mismatched-key isolation loss, effectively preventing cross-key decoding when a wrong key is applied. This design preserves the intended steganographic behavior while addressing a critical security limitation of PUSNet. Extensive experiments demonstrate that PUSNet-MK produces high-quality stego images and accurate secret recovery, while preventing unintended information leakage.

翻译：隐写术将秘密信息隐藏在无害载体中，同时保持视觉保真度并实现可靠恢复。现有统一网络在无触发条件下正常运行，但在触发时切换至隐藏隐写任务。PUSNet遵循该范式，在常规操作时执行图像净化，激活后实施隐写嵌入。然而，该网络仅支持单用户单密钥对，限制了其在多用户场景中的适用性。我们提出PUSNet-MK——一种多密钥扩展方案，通过不匹配密钥隔离损失实现严格的密钥隔离，有效防止错误密钥应用时的跨密钥解码。该设计在保持预期隐写行为的同时，解决了PUSNet的关键安全限制。大量实验表明，PUSNet-MK可生成高质量隐写图像并实现准确的秘密恢复，同时防止意外信息泄露。