fn rfc7748_ladder

fn rfc7748_ladder_test2()

in src/x25519.rs [346:405]
42 lines of code
2 McCabe index (conditional complexity)

    fn rfc7748_ladder_test2() {
        use curve25519_dalek_fiat::constants::X25519_BASEPOINT;

        let mut k: [u8; 32] = X25519_BASEPOINT.0;
        let mut u: [u8; 32] = X25519_BASEPOINT.0;
        let mut result: [u8; 32];

        macro_rules! do_iterations {
            ($n:expr) => {
                for _ in 0..$n {
                    result = x25519(k, u);
                    // OBVIOUS THING THAT I'M GOING TO NOTE ANYWAY BECAUSE I'VE
                    // SEEN PEOPLE DO THIS WITH GOLANG'S STDLIB AND YOU SURE AS
                    // HELL SHOULDN'T DO HORRIBLY STUPID THINGS LIKE THIS WITH
                    // MY LIBRARY:
                    //
                    // NEVER EVER TREAT SCALARS AS POINTS AND/OR VICE VERSA.
                    //
                    //                ↓↓ DON'T DO THIS ↓↓
                    u = k.clone();
                    k = result;
                }
            };
        }

        // After one iteration:
        //     422c8e7a6227d7bca1350b3e2bb7279f7897b87bb6854b783c60e80311ae3079
        // After 1,000 iterations:
        //     684cf59ba83309552800ef566f2f4d3c1c3887c49360e3875f2eb94d99532c51
        // After 1,000,000 iterations:
        //     7c3911e0ab2586fd864497297e575e6f3bc601c0883c30df5f4dd2d24f665424

        do_iterations!(1);
        assert_eq!(
            k,
            [
                0x42, 0x2c, 0x8e, 0x7a, 0x62, 0x27, 0xd7, 0xbc, 0xa1, 0x35, 0x0b, 0x3e, 0x2b, 0xb7,
                0x27, 0x9f, 0x78, 0x97, 0xb8, 0x7b, 0xb6, 0x85, 0x4b, 0x78, 0x3c, 0x60, 0xe8, 0x03,
                0x11, 0xae, 0x30, 0x79,
            ]
        );
        do_iterations!(999);
        assert_eq!(
            k,
            [
                0x68, 0x4c, 0xf5, 0x9b, 0xa8, 0x33, 0x09, 0x55, 0x28, 0x00, 0xef, 0x56, 0x6f, 0x2f,
                0x4d, 0x3c, 0x1c, 0x38, 0x87, 0xc4, 0x93, 0x60, 0xe3, 0x87, 0x5f, 0x2e, 0xb9, 0x4d,
                0x99, 0x53, 0x2c, 0x51,
            ]
        );
        do_iterations!(999_000);
        assert_eq!(
            k,
            [
                0x7c, 0x39, 0x11, 0xe0, 0xab, 0x25, 0x86, 0xfd, 0x86, 0x44, 0x97, 0x29, 0x7e, 0x57,
                0x5e, 0x6f, 0x3b, 0xc6, 0x01, 0xc0, 0x88, 0x3c, 0x30, 0xdf, 0x5f, 0x4d, 0xd2, 0xd2,
                0x4f, 0x66, 0x54, 0x24,
            ]
        );
    }