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 ...

Google "bignum C++".

could you please elaborate on ""bignum c++ "" ... can it handle REALLY large numbers ???

Yes, it can handle numbers as large as you like, but you need a library to help you.

Here's a "bignum" library.
http://gmplib.org/

thanks a lot salem ... i think that should solve my problems for now ....