To add authentication features to CP-ABE [cpABE][1] cpABE, I have tried to combine it with the ABS scheme proposed by Maji et. al [maji][2] maji. I want to use the sign() and verify() algorithms of ABS scheme. But the problem is that the two scheme support different access policy structures; CP-ABE uses access trees to define access policy whereas the ABS uses monotone span program (MSP). I want to know what changes I need to make to work them together? Like how can I change the access policy defined in MSP to access trees? I really appreciate the help.