fn test_vartime_pippenger()

in src/backend/vector/scalar_mul/pippenger.rs [134:163]

• 24 lines of code
• 2 McCabe index (conditional complexity)

    fn test_vartime_pippenger() {
        // Reuse points across different tests
        let mut n = 512;
        let x = Scalar::from(2128506u64).invert();
        let y = Scalar::from(4443282u64).invert();
        let points: Vec<_> = (0..n)
            .map(|i| constants::ED25519_BASEPOINT_POINT * Scalar::from(1 + i as u64))
            .collect();
        let scalars: Vec<_> = (0..n)
            .map(|i| x + (Scalar::from(i as u64) * y)) // fast way to make ~random but deterministic scalars
            .collect();

        let premultiplied: Vec<EdwardsPoint> = scalars
            .iter()
            .zip(points.iter())
            .map(|(sc, pt)| sc * pt)
            .collect();

        while n > 0 {
            let scalars = &scalars[0..n].to_vec();
            let points = &points[0..n].to_vec();
            let control: EdwardsPoint = premultiplied[0..n].iter().sum();

            let subject = Pippenger::vartime_multiscalar_mul(scalars.clone(), points.clone());

            assert_eq!(subject.compress(), control.compress());

            n = n / 2;
        }
    }