i need to use large integers of the size 1024 to 2048 in a cryptography project using C... are there any header files available which will make my work easier if not ... how do i hanlde these integers using structures ???

By handling i mean multiplication , exponentation , applying modulus function etc ...

most of the time i'll be using (x^y)(mod p) where the numbers are of the size 1024 to 2048 bits ...