Function fast_correlation_attack 

pub fn fast_correlation_attack(
    keystream: &[bool],
    taps: &[bool],
    max_iters: usize,
) -> Option<Vec<bool>>

Fast correlation attack (Meier–Staffelbach): recover a leaking LFSR’s initial state from a noisy keystream by DECODING the register-as-linear-code, in time polynomial in L — where the exhaustive correlation attack (scan_for_combiner_leaks, Rung E) needs O(2^L). This is what scales the correlation break to the register lengths real ciphers use. See [describe::fast_correlation_attack].