Modulus masking does not work.

I could not get modulus masking working; it keeps generated graphs that fail the verification step due to two keys colliding (i.e. resolving to the same index).  Surprisingly, I ran into the exact same bug when verifying the cmph project (https://github.com/tpn/cmph-2.0), so, I'm not convinced the algorithm has ever worked with modulus masking.