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use std::sync::{Arc, Mutex};
use crate::{
oracle::{LpnOracle, Sample},
random::lpn_thread_rng,
};
use indicatif::ProgressBar;
use m4ri_rust::friendly::BinMatrix;
use m4ri_rust::friendly::BinVector;
use rayon::prelude::*;
use crate::codes::BinaryCode;
use rand::prelude::*;
pub fn sparse_secret_reduce(oracle: &mut LpnOracle) {
let k = oracle.get_k();
let mut rng = lpn_thread_rng();
let searchspace = std::cmp::min(oracle.samples.len(), 1_000_000);
let (m, c_prime, samples) = loop {
let (a, b, samples) = {
let samples: Vec<_> = oracle.samples[..searchspace]
.choose_multiple(&mut rng, k)
.cloned()
.collect();
let mut b = BinVector::with_capacity(k);
(
BinMatrix::new(
samples
.iter()
.map(|q| {
b.push(q.get_product());
q.as_binvector(k)
})
.collect(),
),
b,
samples,
)
};
if a.clone().echelonize() == k {
break (a, b, samples);
}
};
let original_secret = oracle.secret.as_binvector(k);
log::debug!(
"the secret prior to reduction to a sparse secret was: {:?}",
original_secret
);
if oracle.delta == 1.0 {
debug_assert_eq!(
(&original_secret * &m.transposed()),
c_prime,
"this one fails if tau > 0"
);
}
let new_secret = &(&m * &original_secret) + &c_prime;
oracle.secret = Sample::from_binvector(&new_secret, false);
debug_assert_eq!(
(&new_secret + &c_prime) * m.transposed().inverted(),
original_secret
);
let m_t_inv = m.inverted();
log::trace!("removing the samples we took for the transformation matrix");
let mut poses = samples
.into_par_iter()
.map(|sample| {
oracle.samples[..searchspace]
.iter()
.position(|item| item == &sample)
.unwrap()
})
.collect::<Vec<_>>();
poses.sort_unstable();
poses.into_iter().rev().for_each(|pos| {
oracle.samples.swap_remove(pos);
});
let m_t_inv_t = &m_t_inv.transposed();
let progress = ProgressBar::new(oracle.samples.len() as u64);
log::info!("Sparse-secretifying samples");
progress.set_draw_delta(oracle.samples.len() as u64 / 100);
progress.reset();
let progress = Arc::new(Mutex::new(progress));
oracle.samples.par_chunks_mut(10000).for_each(|queries| {
let len_chunk = queries.len();
for query in queries {
let new_v = m_t_inv_t.mul_slice(query.get_sample()).as_vector();
let new_product = query.get_product() ^ &new_v * &c_prime;
*query = Sample::from_binvector(&new_v, new_product);
}
progress.lock().unwrap().inc(len_chunk as u64);
});
progress.lock().unwrap().finish_and_clear();
oracle.sparse_transform_matrix = Some(m);
oracle.sparse_transform_vector = Some(c_prime);
oracle.delta_s = oracle.delta;
}
pub fn unsparse_secret(oracle: &LpnOracle, secret: &BinVector) -> BinVector {
let m = &oracle
.sparse_transform_matrix
.clone()
.expect("Not a sparse oracle");
let c_prime = &oracle.sparse_transform_vector.clone().unwrap();
(secret + c_prime) * m.transposed().inverted()
}
pub fn code_reduce<T: BinaryCode + Sync>(oracle: &mut LpnOracle, code: &T) {
assert!(
oracle.delta_s > 0.0,
"This reduction only works for sparse secrets!"
);
assert_eq!(
oracle.get_k() as usize,
code.length(),
"The length of the code does not match the problem size!"
);
log::info!("Decoding samples");
let progress = ProgressBar::new(oracle.samples.len() as u64);
progress.set_draw_delta(oracle.samples.len() as u64 / 100);
progress.reset();
let progress = Arc::new(Mutex::new(progress));
oracle.samples.par_chunks_mut(10000).for_each(|queries| {
let chunk_len = queries.len();
for query in queries {
code.decode_sample(query)
}
progress.lock().unwrap().inc(chunk_len as u64);
});
progress.lock().unwrap().finish_and_clear();
log::warn!(
"Note that we transformed the secret $s$ into $s'=s*G^T$ with k' = {}!",
oracle.get_k()
);
let k = oracle.get_k();
let gen_t = code.generator_matrix().transposed();
oracle.secret = Sample::from_binvector(&(&oracle.secret.as_binvector(k) * &gen_t), false);
unsafe { oracle.set_k(code.dimension()) };
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_unsparse() {
let mut oracle: LpnOracle = LpnOracle::new(15, 1.0 / 4.0);
oracle.secret =
Sample::from_binvector(&BinVector::from_function(15, |x| x % 2 == 0), false);
let secret = oracle.secret.as_binvector(oracle.get_k());
oracle.get_samples(1000);
sparse_secret_reduce(&mut oracle);
let unsps = unsparse_secret(&oracle, &oracle.secret.as_binvector(oracle.get_k()));
assert_eq!(secret, unsps, "sparse/unsparse unequal");
}
#[cfg(feature = "hamming")]
#[test]
fn test_reduction() {
use crate::codes::HammingCode15_11;
use crate::lf1::fwht_solve;
let mut oracle: LpnOracle = LpnOracle::new(15, 0.0 / 8.0);
oracle.secret =
Sample::from_binvector(&BinVector::from_function(15, |x| x % 2 == 0), false);
oracle.get_samples(1_000_000);
sparse_secret_reduce(&mut oracle);
let code = HammingCode15_11;
code_reduce(&mut oracle, &code);
let secret = oracle.secret.as_binvector(oracle.get_k());
let fwht_solution = fwht_solve(oracle.clone());
assert_eq!(secret, fwht_solution, "Found wrong solution");
}
}