Function ntt_shuffled 

pub fn ntt_shuffled(
    f: &mut [i16; 256],
    rng: &mut impl CryptoRng,
) -> Result<(), MlKemError>

Forward NTT with randomized butterfly ordering (SPA countermeasure).

Functionally equivalent to super::ntt::ntt but randomizes the execution order of butterfly operations at each NTT level. Both the group order (which butterfly group runs first) and the intra-group order (which pair within a group runs first) are independently shuffled using fresh generate_permutation calls.

A new random permutation is generated for every level and every group, so successive invocations produce different power traces even for identical inputs.

Arguments

• f - A mutable reference to a 256-coefficient polynomial. Modified in place.
• rng - A cryptographic RNG for generating shuffle permutations.

Errors

Returns MlKemError::RngFailure if the RNG fails during permutation generation.