arnaucube/poulpy
1
0
Fork 0
mirror of https://github.com/arnaucube/poulpy.git synced 2026-02-10 13:16:44 +01:00
Code Issues Packages Projects Releases Wiki Activity

Fixed gadget product & added noise estimations

Browse Source
This commit is contained in:
Jean-Philippe Bossuat
2025-02-24 08:31:02 +01:00
parent 014bf0c2d1
commit 26c2bcbc05
24 changed files with 762 additions and 473 deletions
Download Patch File Download Diff File Expand all files Collapse all files

371
rlwe/src/gadget_product.rs Normal file
View File

@@ -0,0 +1,371 @@
use crate::{
ciphertext::Ciphertext,
elem::{Elem, ElemCommon, ElemVecZnx, VecZnxCommon},
parameters::Parameters,
};
use base2k::{Module, VecZnxDft, VecZnxDftOps, VmpPMat, VmpPMatOps};
use std::cmp::min;
pub fn gadget_product_tmp_bytes(
module: &Module,
log_base2k: usize,
res_log_q: usize,
in_log_q: usize,
gct_rows: usize,
gct_log_q: usize,
) -> usize {
let gct_cols: usize = (gct_log_q + log_base2k - 1) / log_base2k;
let in_cols: usize = (in_log_q + log_base2k - 1) / log_base2k;
let out_cols: usize = (res_log_q + log_base2k - 1) / log_base2k;
module.vmp_apply_dft_to_dft_tmp_bytes(out_cols, in_cols, gct_rows, gct_cols)
}
impl Parameters {
pub fn gadget_product_tmp_bytes(
&self,
res_log_q: usize,
in_log_q: usize,
gct_rows: usize,
gct_log_q: usize,
) -> usize {
gadget_product_tmp_bytes(
self.module(),
self.log_base2k(),
res_log_q,
in_log_q,
gct_rows,
gct_log_q,
)
}
}
/// Evaluates the gadget product res <- a x b.
///
/// # Arguments
///
/// * `module`: backend support for operations mod (X^N + 1).
/// * `res`: an [Elem] to store (-cs + m * a + e, c) with res_ncols cols.
/// * `a`: a [VecZnx] of a_ncols cols.
/// * `b`: a [Ciphertext<VmpPMat>] as a vector of (-Bs + m * 2^{-k} + E, B)
/// containing b_nrows [VecZnx], each of b_ncols cols.
///
/// # Computation
///
/// res = sum[min(a_ncols, b_nrows)] decomp(a, i) * (-B[i]s + m * 2^{-k*i} + E[i], B[i])
/// = (cs + m * a + e, c) with min(res_cols, b_cols) cols.
pub fn gadget_product_core<const OVERWRITE: bool, T>(
module: &Module,
res_dft_0: &mut VecZnxDft,
res_dft_1: &mut VecZnxDft,
a: &T,
a_cols: usize,
b: &Ciphertext<VmpPMat>,
b_cols: usize,
tmp_bytes: &mut [u8],
) where
T: VecZnxCommon<Owned = T>,
Elem<T>: ElemVecZnx<T>,
{
assert!(b_cols <= b.cols());
module.vec_znx_dft(res_dft_1, a, a_cols);
module.vmp_apply_dft_to_dft(res_dft_0, res_dft_1, b.at(0), tmp_bytes);
module.vmp_apply_dft_to_dft_inplace(res_dft_1, b.at(1), tmp_bytes);
}
/*
// res_big[a * (G0|G1)] <- IDFT(res_dft[a * (G0|G1)])
module.vec_znx_idft_tmp_a(&mut res_big_0, &mut res_dft_0, b_cols);
module.vec_znx_idft_tmp_a(&mut res_big_1, &mut res_dft_1, b_cols);
// res_big <- res[0] + res_big[a*G0]
module.vec_znx_big_add_small_inplace(&mut res_big_0, res.at(0));
module.vec_znx_big_normalize(log_base2k, res.at_mut(0), &res_big_0, tmp_bytes_carry);
if OVERWRITE {
// res[1] = normalize(res_big[a*G1])
module.vec_znx_big_normalize(log_base2k, res.at_mut(1), &res_big_1, tmp_bytes_carry);
} else {
// res[1] = normalize(res_big[a*G1] + res[1])
module.vec_znx_big_add_small_inplace(&mut res_big_1, res.at(1));
module.vec_znx_big_normalize(log_base2k, res.at_mut(1), &res_big_1, tmp_bytes_carry);
}
*/
#[cfg(test)]
mod test {
use crate::{
ciphertext::{Ciphertext, new_gadget_ciphertext},
decryptor::decrypt_rlwe,
elem::{Elem, ElemCommon, ElemVecZnx},
encryptor::encrypt_grlwe_sk,
gadget_product::gadget_product_core,
keys::SecretKey,
parameters::{Parameters, ParametersLiteral},
plaintext::Plaintext,
};
use base2k::{
FFT64, Infos, Sampling, SvpPPolOps, VecZnx, VecZnxApi, VecZnxBig, VecZnxBigOps, VecZnxDft,
VecZnxDftOps, VecZnxOps, VmpPMat,
};
use sampling::source::{Source, new_seed};
#[test]
fn test_gadget_product_core() {
let log_base2k: usize = 10;
let q_cols: usize = 7;
let p_cols: usize = 1;
// Basic parameters with enough limbs to test edge cases
let params_lit: ParametersLiteral = ParametersLiteral {
log_n: 12,
log_q: q_cols * log_base2k,
log_p: p_cols * log_base2k,
log_base2k: log_base2k,
log_scale: 20,
xe: 3.2,
xs: 1 << 11,
};
let params: Parameters = Parameters::new::<FFT64>(&params_lit);
// scratch space
let mut tmp_bytes: Vec<u8> =
vec![
0u8;
params.decrypt_rlwe_tmp_byte(params.log_qp())
| params.encrypt_rlwe_sk_tmp_bytes(params.log_qp())
| params.gadget_product_tmp_bytes(
params.log_qp(),
params.log_qp(),
params.cols_qp(),
params.log_qp()
)
| params.encrypt_grlwe_sk_tmp_bytes(params.cols_qp(), params.log_qp())
];
// Samplers for public and private randomness
let mut source_xe: Source = Source::new(new_seed());
let mut source_xa: Source = Source::new(new_seed());
let mut source_xs: Source = Source::new(new_seed());
// Two secret keys
let mut sk0: SecretKey = SecretKey::new(params.module());
sk0.fill_ternary_hw(params.xs(), &mut source_xs);
let mut sk0_svp_ppol: base2k::SvpPPol = params.module().new_svp_ppol();
params.module().svp_prepare(&mut sk0_svp_ppol, &sk0.0);
let mut sk1: SecretKey = SecretKey::new(params.module());
sk1.fill_ternary_hw(params.xs(), &mut source_xs);
let mut sk1_svp_ppol: base2k::SvpPPol = params.module().new_svp_ppol();
params.module().svp_prepare(&mut sk1_svp_ppol, &sk1.0);
// The gadget ciphertext
let mut gadget_ct: Ciphertext<VmpPMat> = new_gadget_ciphertext(
params.module(),
log_base2k,
params.cols_qp(),
params.log_qp(),
);
// gct = [-b*sk1 + g(sk0) + e, b]
encrypt_grlwe_sk(
params.module(),
&mut gadget_ct,
&sk0.0,
&sk1_svp_ppol,
&mut source_xa,
&mut source_xe,
params.xe(),
&mut tmp_bytes,
);
// Intermediate buffers
let mut res_dft_0: VecZnxDft = params.module().new_vec_znx_dft(gadget_ct.cols());
let mut res_dft_1: VecZnxDft = params.module().new_vec_znx_dft(gadget_ct.cols());
let mut res_big_0: VecZnxBig = res_dft_0.as_vec_znx_big();
let mut res_big_1: VecZnxBig = res_dft_1.as_vec_znx_big();
// Input polynopmial, uniformly distributed
let mut a: VecZnx = params.module().new_vec_znx(params.cols_q());
params
.module()
.fill_uniform(log_base2k, &mut a, params.cols_q(), &mut source_xa);
// res = g^-1(a) * gct
let mut elem_res: Elem<VecZnx> =
Elem::<VecZnx>::new(params.module(), log_base2k, params.log_qp(), 2);
// Ideal output = a * s
let mut a_dft: VecZnxDft = params.module().new_vec_znx_dft(a.cols());
let mut a_big: VecZnxBig = a_dft.as_vec_znx_big();
let mut a_times_s: VecZnx = params.module().new_vec_znx(a.cols());
// a * sk0
params
.module()
.svp_apply_dft(&mut a_dft, &sk0_svp_ppol, &a, a.cols());
params
.module()
.vec_znx_idft_tmp_a(&mut a_big, &mut a_dft, a.cols());
params.module().vec_znx_big_normalize(
params.log_base2k(),
&mut a_times_s,
&a_big,
&mut tmp_bytes,
);
// Plaintext for decrypted output of gadget product
let mut pt: Plaintext<VecZnx> =
Plaintext::<VecZnx>::new(params.module(), params.log_base2k(), params.log_qp());
// Iterates over all possible cols values for input/output polynomials and gadget ciphertext.
pt.elem_mut().zero();
elem_res.zero();
let a_cols: usize = a.cols() - 1;
let b_cols: usize = gadget_ct.cols();
println!("a_cols: {} b_cols: {}", a_cols, b_cols);
// res_dft_0 = DFT(gct_[0] * ct[1] = a * (-bs' + s + e) = -cs' + as + e')
// res_dft_1 = DFT(gct_[1] * ct[1] = a * b = c)
gadget_product_core::<true, _>(
params.module(),
&mut res_dft_0,
&mut res_dft_1,
&a,
a_cols,
&gadget_ct,
b_cols,
&mut tmp_bytes,
);
// res_big_0 = IDFT(res_dft_0)
params
.module()
.vec_znx_idft_tmp_a(&mut res_big_0, &mut res_dft_0, b_cols);
// res_big_1 = IDFT(res_dft_1);
params
.module()
.vec_znx_idft_tmp_a(&mut res_big_1, &mut res_dft_1, b_cols);
// res_big_0 = normalize(res_big_0)
params.module().vec_znx_big_normalize(
log_base2k,
elem_res.at_mut(0),
&res_big_0,
&mut tmp_bytes,
);
// res_big_1 = normalize(res_big_1)
params.module().vec_znx_big_normalize(
log_base2k,
elem_res.at_mut(1),
&res_big_1,
&mut tmp_bytes,
);
// <(-c*sk1 + a*sk0 + e, a), (1, sk1)> = a*sk0 + e
decrypt_rlwe(
params.module(),
pt.elem_mut(),
&elem_res,
&sk1_svp_ppol,
&mut tmp_bytes,
);
// a * sk0 + e - a*sk0 = e
params
.module()
.vec_znx_sub_inplace(pt.at_mut(0), &mut a_times_s);
pt.at_mut(0).normalize(log_base2k, &mut tmp_bytes);
pt.at(0).print(pt.elem().cols(), 16);
println!("noise_have: {}", pt.at(0).std(log_base2k).log2());
let var_a_err: f64;
if a_cols < a.cols() {
var_a_err = 1f64 / 12f64;
} else {
var_a_err = 0f64;
}
let a_logq: usize = a_cols * log_base2k;
let b_logq: usize = b_cols * log_base2k;
let var_msg: f64 = params.xs() as f64;
println!(
"noise_pred: {}",
params.noise_grlwe_product(var_msg, var_a_err, a_logq, b_logq)
);
}
}
impl Parameters {
pub fn noise_grlwe_product(
&self,
var_msg: f64,
var_a_err: f64,
a_logq: usize,
b_logq: usize,
) -> f64 {
let n: f64 = self.n() as f64;
let var_xs: f64 = self.xs() as f64;
let var_gct_err_lhs: f64;
let var_gct_err_rhs: f64;
if b_logq < self.log_qp() {
let var_round: f64 = 1f64 / 12f64;
var_gct_err_lhs = var_round;
var_gct_err_rhs = var_round;
} else {
var_gct_err_lhs = self.xe() * self.xe();
var_gct_err_rhs = 0f64;
}
noise_grlwe_product(
n,
self.log_base2k(),
var_xs,
var_msg,
var_a_err,
var_gct_err_lhs,
var_gct_err_rhs,
a_logq,
b_logq,
)
}
}
pub fn noise_grlwe_product(
n: f64,
log_base2k: usize,
var_xs: f64,
var_msg: f64,
var_a_err: f64,
var_gct_err_lhs: f64,
var_gct_err_rhs: f64,
a_logq: usize,
b_logq: usize,
) -> f64 {
let a_cols: usize = (a_logq + log_base2k - 1) / log_base2k;
let b_cols: usize = (b_logq + log_base2k - 1) / log_base2k;
let b_scale = 2.0f64.powi(b_logq as i32);
let a_scale: f64 = 2.0f64.powi((b_logq - a_logq) as i32);
let base: f64 = (1 << (log_base2k)) as f64;
let var_base: f64 = base * base / 12f64;
let var_round: f64 = 1f64 / 12f64;
// lhs = a_cols * n * (var_base * var_gct_err_lhs + var_e_a * var_msg * p^2)
// rhs = a_cols * n * var_base * var_gct_err_rhs * var_xs
let mut noise: f64 =
(a_cols as f64) * n * var_base * (var_gct_err_lhs + var_xs * var_gct_err_rhs);
noise += var_msg * var_a_err * a_scale * a_scale;
noise = noise.sqrt();
noise /= b_scale;
noise.log2()
}