近年來雲端運算的快速發展，使得將資料上傳至雲端伺服器已成為現代資訊系統的常見模式。然而，在確保資料機密性的同時仍允許伺服器對加密資料進行搜尋，成為一項挑戰。可搜尋加密（Searchable Encryption）技術允許使用者在不解密資料的情況下執行查詢，但多數既有機制並未考慮使用者在脅迫情境下可能被迫揭露搜尋憑證或查詢內容的問題。
為了解決此問題，本研究提出一個通用的「可否認可搜尋加密（Deniable Searchable Encryption, DSE）」框架。我們將「公開金鑰可搜尋加密（Public Key Encryption with Keyword Search, PEKS）」抽象為一個滿足「選擇關鍵字攻擊安全性（Indistinguishability against Chosen Keyword Attack, IND-CKA）」的搜尋元件，並利用「身份基加密（Identity-Based Encryption, IBE）」作為否認性機制，設計一個模組化的轉換方法。透過此方法，可在不犧牲效率的情況下，將任一具 IND-CKA 安全性的具表達性 PEKS 機制轉換為具備抵抗脅迫能力的搜尋加密系統。
我們並證明，若底層 PEKS 滿足 IND-CKA 安全性且 IBE 滿足匿名選擇明文攻擊安全性（Anonymous Indistinguishability under Chosen Plaintext Attack, ANON-CPA），則所提出的 DSE 建構可同時達成關鍵字隱私與抵抗脅迫之否認性。

Recent rapid advances in cloud computing have made uploading data to cloud servers a common practice in modern information systems. However, allowing servers to perform searches over encrypted data while ensuring data confidentiality remains a challenge. Searchable Encryption (SE) enables users to perform queries without decrypting the data, but most existing schemes do not consider scenarios in which users may be forced to reveal search credentials or query contents under coercion.
To address this issue, this study proposes a generic framework for Deniable Searchable Encryption (DSE). We abstract Public Key Encryption with Keyword Search (PEKS) as a search component that satisfies Indistinguishability against Chosen Keyword Attack (IND-CKA) security, and use Identity-Based Encryption (IBE) as the deniability mechanism to design a modular transformation method. Through this method, any expressive PEKS scheme that satisfies IND-CKA security can be transformed into a searchable encryption system with coercion resistance without sacrificing efficiency.
We further prove that if the underlying PEKS satisfies IND-CKA security and the IBE satisfies Anonymous Indistinguishability under Chosen Plaintext Attack (ANON-CPA) security, then the proposed DSE construction simultaneously achieves keyword privacy and coercion-resistant deniability.

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