Abstract

In Internet of Things (IoT), encryption is a technique in which plaintext is converted to ciphertext to make it non-recovered by the attacker without secret key. Ciphertext policy attribute based encryption (CP-ABE) is an encryption technique aimed at multicasting feature i.e. user can only decrypt the message if policy of attributes mentioned in ciphertext is satisfied by the user’s secret key attributes. In literature, the authors have improvised the existing technique to enhance the naïve CP-ABE scheme. Recently, in 2021, Wang et al. have proposed the CP-ABE scheme with proxy re-encryption and claimed it to be efficient as to its predecessors. However, it follows the variable length ciphertext in which size of ciphertext is increased with the number of attributes. Also, it leads to computation overhead on the receiver during decryption which will be performed by the IoT devices. Thus, in this paper we have proposed the improved scheme to provide the constant length ciphertext with proxy re-encryption to reduce the computation and communication time. The proposed scheme is secured under Decisional Bilinear Diffie-Hellman (DBDH) problem.

Key words: Attribute, multi-authority, proxy re-encryption, constant length