Effective key generation for Naccache-Stern

[serengil]

Currently, we set the key length of Naccace-Stern to 37 bits here and here

This is working fine but if we increase the key length, then it cannot find any keys for a long time. TBH, I never see a key is found.

We need to find a way to generate larger keys. This is answered in a stackoverflow post but when I do it, still it is not working.