Abstract—Ciphertext-Policy Attribute-Based Encryption (CP-ABE) is an advanced encryption method used across various fields, including cloud storage, Personal Health Records, Internet of Things, Internet of Vehicles, and blockchain. However, challenges such as insufficient security levels and performance issues in modern applications pose significant drawbacks inherent to the CP-ABE scheme. Previously, we studied Efficient Library for Pairing Systems (ELiPS)-Based CP-ABE to enhance performance and strengthen security level. This approach involved adopting ELiPS as an efficient library for pairing systems. This study increased the security level up to 128 bits and reduced the computation cost, excluding the decryption process. The decryption part primarily utilizes inversion in the Lagrange coefficient part and pairing, which includes the Miller loop and final exponentiation. Both the final exponentiation and inversion are equivalent to the number of attributes. In this paper, we further explore reducing the decryption process time by minimizing the number of final exponentiations and inversions. The effectiveness of the proposal is confirmed through security and experimental analyses where the decryption time in the proposed scheme decreased by an average of 45.45% compared to previous work.
 
Keywords—Pairing-Based Cryptography, Attribute-Based Encryption, Ciphertext-Policy Attribute-Based Encryption (CP-ABE), Efficient Library for Pairing Systems (ELiPS), ELiPS-Based CP-ABE, pairing


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