How to handle big integers in C

Question

I want to implement cryptography algorithms. So I need a suitable data type to handle integers with a lot of digits.

Many recent languages, such as Java, Python and

Answer 1

I would first off highly suggest using an already existing library.

However, I have done this before in the past as an experiment. I choose option 2. Representing a value like "10000000002000000000" as

int array[2] = { 1000000000, 2000000000 } 

and performing operations and carry values one int at a time. Not very efficient, but functionally sound.