I need to implement cryptographic operations starting with the curve NISTP256. I have been told to implement it using Montgomery method. I read a pfd from http://saluc.engr.uconn.edu/refs/sidechannel/okeya00elliptic.pdf. It states that the order of the curve must be divisible by 4. But the curve's order is not a multiple of 4.
So does that mean the curve cannot be implemented using Montgomery method or is there any other ways to implement it?