How to pass 128 bit Long value to cdll function expecting const unsigned char*

[Sana007]

from ctypes import*

cdll = "Windll"
var = 0x1fffffffffffffffffffffff # I want to send this long variable to character pointer which is in cdll


cdll.createBuff (var)

cdll function
int createBuff (const unsigned char*){
   print charBuff
   return 0;
}

Facing a issue in passing 128 bit Long value to cdll function expecting const unsigned char*.how could i achieve this, I researched on this topic, i found ctypes in python. I didnt get any clue to solve using in ctypes. Please help me sorting out this issue.