Efficient Conditional Proxy Re-Encryption with Chosen-Ciphertext Security

• Main Authors: WENG, Jian, YANG, Yanjiang, TANG, Qiang, DENG, Robert H.
• Format: text
• Language: English
• Published: Institutional Knowledge at Singapore Management University 2009
• Subjects: Conditional proxy re-encryption; chosen-ciphertext security; random oracle; Information Security
• Online Access: https://ink.library.smu.edu.sg/sis_research/476; https://ink.library.smu.edu.sg/context/sis_research/article/1475/viewcontent/11472003.pdf
• Institution: Singapore Management University

Recently, a variant of proxy re-encryption, named conditional proxy re-encryption (C-PRE), has been introduced. Compared with traditional proxy re-encryption, C-PRE enables the delegator to implement fine-grained delegation of decryption rights, and thus is more useful in many applications. In this paper, based on a careful observation on the existing definitions and security notions for C-PRE, we re-formalize more rigorous definition and security notions for C-PRE. We further propose a more efficient C-PRE scheme, and prove its chosen-ciphertext security under the decisional bilinear Diffie-Hellman (DBDH) assumption in the random oracle model. In addition, we point out that a recent C-PRE scheme fails to achieve the chosen-ciphertext security.