fn vartime_precomputed_vs_nonprecomputed_multiscalar()

in src/edwards.rs [1332:1372]

• 31 lines of code
• 1 McCabe index (conditional complexity)

    fn vartime_precomputed_vs_nonprecomputed_multiscalar() {
        let mut rng = rand::thread_rng();

        let B = &::constants::ED25519_BASEPOINT_TABLE;

        let static_scalars = (0..128)
            .map(|_| Scalar::random(&mut rng))
            .collect::<Vec<_>>();

        let dynamic_scalars = (0..128)
            .map(|_| Scalar::random(&mut rng))
            .collect::<Vec<_>>();

        let check_scalar: Scalar = static_scalars
            .iter()
            .chain(dynamic_scalars.iter())
            .map(|s| s * s)
            .sum();

        let static_points = static_scalars.iter().map(|s| s * B).collect::<Vec<_>>();
        let dynamic_points = dynamic_scalars.iter().map(|s| s * B).collect::<Vec<_>>();

        let precomputation = VartimeEdwardsPrecomputation::new(static_points.iter());

        let P = precomputation.vartime_mixed_multiscalar_mul(
            &static_scalars,
            &dynamic_scalars,
            &dynamic_points,
        );

        use traits::VartimeMultiscalarMul;
        let Q = EdwardsPoint::vartime_multiscalar_mul(
            static_scalars.iter().chain(dynamic_scalars.iter()),
            static_points.iter().chain(dynamic_points.iter()),
        );

        let R = &check_scalar * B;

        assert_eq!(P.compress(), R.compress());
        assert_eq!(Q.compress(), R.compress());
    }