Compact Attribute-Based Encryption and Signcryption for General Circuits from Multilinear Maps

In this paper, we start by presenting a key-policy attribute-based encryption ABE supporting general polynomial-size circuit realizable decryption policies and featuring compactness in the sense that our ABE construction exhibits short ciphertexts and shorter decryption keys compared to existing similar works. We then design a key-policy attribute-based signcryption ABSC scheme which enjoys several interesting properties that were never achievable before. It supports signing and decryption policies representable as arbitrary polynomial-size circuits. Besides, it generates short ciphertext. Our constructions employ multilinear map and achieve selective security in the standard model under standard complexity assumptions. More interestingly, our key-policy constructions can be converted to the corresponding ciphertext-policy variants achieving short ciphertext by utilizing the technique of universal circuits.