Function discrete_log_index_calculus 

pub fn discrete_log_index_calculus(
    n: &Integer,
    a: &Integer,
    b: &Integer,
    order: Option<&Integer>,
) -> Result<Integer, Error>

Index Calculus algorithm for computing the discrete logarithm of a in base b modulo n.

The group order must be given and prime. It is not suitable for small orders and the algorithm might fail to find a solution in such situations.

This algorithm is particularly efficient for large prime orders when exp(2*sqrt(log(n)*log(log(n)))) < sqrt(order).

Examples

use discrete_logarithm::discrete_log_index_calculus;
use rug::Integer;

let n = Integer::from(24570203447_u64);
let a = Integer::from(23859756228_u64);
let b = Integer::from(2);
let order = Integer::from(12285101723_u64);

let x = discrete_log_index_calculus(&n, &a, &b, Some(&order)).unwrap();
assert_eq!(x, Integer::from(4519867240_u64));

If the order of the group is known, it must be passed as order.