基於屬性的加密能夠對加密資料進行細粒度的存取控制。然而，基於屬性的加密需要由一個單一的可信機構來頒發解密用的金鑰，這會導致它存在著密鑰托管問題。如果有攻擊者攻破了系統，則該攻擊者可以解密所有通過該系統來進行加解密的密文。

在本論文中，我們將基於註冊的加密的概念擴展到密鑰策略屬性加密中。通過引入基於註冊的加密，讓用戶可以自行生成自己的公私鑰對，從而有效地解決密鑰策略屬性加密的密鑰托管問題。

Attributed-based encryption (ABE) enables fine-grained access control over encrypted data. However, ABE requires a single trusted authority to issue decryption keys, which makes ABE have a key-escrow problem. If an adversary breaks through the system, then the adversary can decrypt all ciphertext encrypted through the system.

In this work, we generalize the notion of registration-based encryption (RBE) to key-policy attributed-based encryption (KP-ABE). Through the introduction of RBE, users can autonomously generate their own keys, thereby effectively resolving the key-escrow problem of KP-ABE.

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