Files
poulpy/rlwe/src/encryptor.rs
Jean-Philippe Bossuat 54148acf6b more refactoring
2025-04-26 13:19:22 +02:00

370 lines
11 KiB
Rust

use crate::ciphertext::Ciphertext;
use crate::elem::{Elem, ElemCommon, ElemVecZnx};
use crate::keys::SecretKey;
use crate::parameters::Parameters;
use crate::plaintext::Plaintext;
use base2k::sampling::Sampling;
use base2k::{
ZnxInfos, Module, Scalar, ScalarZnxDft, ScalarZnxDftOps, VecZnx, VecZnxBig, VecZnxBigOps, VecZnxDft, VecZnxDftOps, VecZnxOps, MatZnxDft,
MatZnxDftOps,
};
use sampling::source::{Source, new_seed};
impl Parameters {
pub fn encrypt_rlwe_sk_tmp_bytes(&self, log_q: usize) -> usize {
encrypt_rlwe_sk_tmp_bytes(self.module(), self.log_base2k(), log_q)
}
pub fn encrypt_rlwe_sk(
&self,
ct: &mut Ciphertext<VecZnx>,
pt: Option<&Plaintext>,
sk: &ScalarZnxDft,
source_xa: &mut Source,
source_xe: &mut Source,
tmp_bytes: &mut [u8],
) {
encrypt_rlwe_sk(
self.module(),
&mut ct.0,
pt.map(|pt| pt.at(0)),
sk,
source_xa,
source_xe,
self.xe(),
tmp_bytes,
)
}
}
pub struct EncryptorSk {
sk: ScalarZnxDft,
source_xa: Source,
source_xe: Source,
initialized: bool,
tmp_bytes: Vec<u8>,
}
impl EncryptorSk {
pub fn new(params: &Parameters, sk: Option<&SecretKey>) -> Self {
let mut sk_svp_ppol: ScalarZnxDft = params.module().new_svp_ppol();
let mut initialized: bool = false;
if let Some(sk) = sk {
sk.prepare(params.module(), &mut sk_svp_ppol);
initialized = true;
}
Self {
sk: sk_svp_ppol,
initialized,
source_xa: Source::new(new_seed()),
source_xe: Source::new(new_seed()),
tmp_bytes: vec![0u8; params.encrypt_rlwe_sk_tmp_bytes(params.cols_qp())],
}
}
pub fn set_sk(&mut self, module: &Module, sk: &SecretKey) {
sk.prepare(module, &mut self.sk);
self.initialized = true;
}
pub fn seed_source_xa(&mut self, seed: [u8; 32]) {
self.source_xa = Source::new(seed)
}
pub fn seed_source_xe(&mut self, seed: [u8; 32]) {
self.source_xe = Source::new(seed)
}
pub fn encrypt_rlwe_sk(&mut self, params: &Parameters, ct: &mut Ciphertext<VecZnx>, pt: Option<&Plaintext>) {
assert!(
self.initialized == true,
"invalid call to [EncryptorSk.encrypt_rlwe_sk]: [EncryptorSk] has not been initialized with a [SecretKey]"
);
params.encrypt_rlwe_sk(
ct,
pt,
&self.sk,
&mut self.source_xa,
&mut self.source_xe,
&mut self.tmp_bytes,
);
}
pub fn encrypt_rlwe_sk_core(
&self,
params: &Parameters,
ct: &mut Ciphertext<VecZnx>,
pt: Option<&Plaintext>,
source_xa: &mut Source,
source_xe: &mut Source,
tmp_bytes: &mut [u8],
) {
assert!(
self.initialized == true,
"invalid call to [EncryptorSk.encrypt_rlwe_sk]: [EncryptorSk] has not been initialized with a [SecretKey]"
);
params.encrypt_rlwe_sk(ct, pt, &self.sk, source_xa, source_xe, tmp_bytes);
}
}
pub fn encrypt_rlwe_sk_tmp_bytes(module: &Module, log_base2k: usize, log_q: usize) -> usize {
module.bytes_of_vec_znx_dft(1, (log_q + log_base2k - 1) / log_base2k) + module.vec_znx_big_normalize_tmp_bytes()
}
pub fn encrypt_rlwe_sk(
module: &Module,
ct: &mut Elem<VecZnx>,
pt: Option<&VecZnx>,
sk: &ScalarZnxDft,
source_xa: &mut Source,
source_xe: &mut Source,
sigma: f64,
tmp_bytes: &mut [u8],
) {
encrypt_rlwe_sk_core::<0>(module, ct, pt, sk, source_xa, source_xe, sigma, tmp_bytes)
}
fn encrypt_rlwe_sk_core<const PT_POS: u8>(
module: &Module,
ct: &mut Elem<VecZnx>,
pt: Option<&VecZnx>,
sk: &ScalarZnxDft,
source_xa: &mut Source,
source_xe: &mut Source,
sigma: f64,
tmp_bytes: &mut [u8],
) {
let cols: usize = ct.cols();
let log_base2k: usize = ct.log_base2k();
let log_q: usize = ct.log_q();
assert!(
tmp_bytes.len() >= encrypt_rlwe_sk_tmp_bytes(module, log_base2k, log_q),
"invalid tmp_bytes: tmp_bytes={} < encrypt_rlwe_sk_tmp_bytes={}",
tmp_bytes.len(),
encrypt_rlwe_sk_tmp_bytes(module, log_base2k, log_q)
);
let log_q: usize = ct.log_q();
let log_base2k: usize = ct.log_base2k();
let c1: &mut VecZnx = ct.at_mut(1);
// c1 <- Z_{2^prec}[X]/(X^{N}+1)
module.fill_uniform(log_base2k, c1, cols, source_xa);
let (tmp_bytes_vec_znx_dft, tmp_bytes_normalize) = tmp_bytes.split_at_mut(module.bytes_of_vec_znx_dft(1, cols));
// Scratch space for DFT values
let mut buf_dft: VecZnxDft = VecZnxDft::from_bytes_borrow(module, 1, cols, tmp_bytes_vec_znx_dft);
// Applies buf_dft <- DFT(s) * DFT(c1)
module.svp_apply_dft(&mut buf_dft, sk, c1);
// Alias scratch space
let mut buf_big: VecZnxBig = buf_dft.as_vec_znx_big();
// buf_big = s x c1
module.vec_znx_idft_tmp_a(&mut buf_big, &mut buf_dft);
match PT_POS {
// c0 <- -s x c1 + m
0 => {
let c0: &mut VecZnx = ct.at_mut(0);
if let Some(pt) = pt {
module.vec_znx_big_sub_small_a_inplace(&mut buf_big, pt);
module.vec_znx_big_normalize(log_base2k, c0, &buf_big, tmp_bytes_normalize);
} else {
module.vec_znx_big_normalize(log_base2k, c0, &buf_big, tmp_bytes_normalize);
module.vec_znx_negate_inplace(c0);
}
}
// c1 <- c1 + m
1 => {
if let Some(pt) = pt {
module.vec_znx_add_inplace(c1, pt);
c1.normalize(log_base2k, tmp_bytes_normalize);
}
let c0: &mut VecZnx = ct.at_mut(0);
module.vec_znx_big_normalize(log_base2k, c0, &buf_big, tmp_bytes_normalize);
module.vec_znx_negate_inplace(c0);
}
_ => panic!("PT_POS must be 1 or 2"),
}
// c0 <- -s x c1 + m + e
module.add_normal(
log_base2k,
ct.at_mut(0),
log_q,
source_xe,
sigma,
(sigma * 6.0).ceil(),
);
}
impl Parameters {
pub fn encrypt_grlwe_sk_tmp_bytes(&self, rows: usize, log_q: usize) -> usize {
encrypt_grlwe_sk_tmp_bytes(self.module(), self.log_base2k(), rows, log_q)
}
}
pub fn encrypt_grlwe_sk_tmp_bytes(module: &Module, log_base2k: usize, rows: usize, log_q: usize) -> usize {
let cols = (log_q + log_base2k - 1) / log_base2k;
Elem::<VecZnx>::bytes_of(module, log_base2k, log_q, 2)
+ Plaintext::bytes_of(module, log_base2k, log_q)
+ encrypt_rlwe_sk_tmp_bytes(module, log_base2k, log_q)
+ module.vmp_prepare_tmp_bytes(rows, cols)
}
pub fn encrypt_grlwe_sk(
module: &Module,
ct: &mut Ciphertext<MatZnxDft>,
m: &Scalar,
sk: &ScalarZnxDft,
source_xa: &mut Source,
source_xe: &mut Source,
sigma: f64,
tmp_bytes: &mut [u8],
) {
let log_q: usize = ct.log_q();
let log_base2k: usize = ct.log_base2k();
let (left, right) = ct.0.value.split_at_mut(1);
encrypt_grlwe_sk_core::<0>(
module,
log_base2k,
[&mut left[0], &mut right[0]],
log_q,
m,
sk,
source_xa,
source_xe,
sigma,
tmp_bytes,
)
}
impl Parameters {
pub fn encrypt_rgsw_sk_tmp_bytes(&self, rows: usize, log_q: usize) -> usize {
encrypt_rgsw_sk_tmp_bytes(self.module(), self.log_base2k(), rows, log_q)
}
}
pub fn encrypt_rgsw_sk_tmp_bytes(module: &Module, log_base2k: usize, rows: usize, log_q: usize) -> usize {
let cols = (log_q + log_base2k - 1) / log_base2k;
Elem::<VecZnx>::bytes_of(module, log_base2k, log_q, 2)
+ Plaintext::bytes_of(module, log_base2k, log_q)
+ encrypt_rlwe_sk_tmp_bytes(module, log_base2k, log_q)
+ module.vmp_prepare_tmp_bytes(rows, cols)
}
pub fn encrypt_rgsw_sk(
module: &Module,
ct: &mut Ciphertext<MatZnxDft>,
m: &Scalar,
sk: &ScalarZnxDft,
source_xa: &mut Source,
source_xe: &mut Source,
sigma: f64,
tmp_bytes: &mut [u8],
) {
let log_q: usize = ct.log_q();
let log_base2k: usize = ct.log_base2k();
let (left, right) = ct.0.value.split_at_mut(2);
let (ll, lr) = left.split_at_mut(1);
let (rl, rr) = right.split_at_mut(1);
encrypt_grlwe_sk_core::<0>(
module,
log_base2k,
[&mut ll[0], &mut lr[0]],
log_q,
m,
sk,
source_xa,
source_xe,
sigma,
tmp_bytes,
);
encrypt_grlwe_sk_core::<1>(
module,
log_base2k,
[&mut rl[0], &mut rr[0]],
log_q,
m,
sk,
source_xa,
source_xe,
sigma,
tmp_bytes,
);
}
fn encrypt_grlwe_sk_core<const PT_POS: u8>(
module: &Module,
log_base2k: usize,
mut ct: [&mut MatZnxDft; 2],
log_q: usize,
m: &Scalar,
sk: &ScalarZnxDft,
source_xa: &mut Source,
source_xe: &mut Source,
sigma: f64,
tmp_bytes: &mut [u8],
) {
let rows: usize = ct[0].rows();
let min_tmp_bytes_len = encrypt_grlwe_sk_tmp_bytes(module, log_base2k, rows, log_q);
assert!(
tmp_bytes.len() >= min_tmp_bytes_len,
"invalid tmp_bytes: tmp_bytes.len()={} < encrypt_grlwe_sk_tmp_bytes={}",
tmp_bytes.len(),
min_tmp_bytes_len
);
let bytes_of_elem: usize = Elem::<VecZnx>::bytes_of(module, log_base2k, log_q, 2);
let bytes_of_pt: usize = Plaintext::bytes_of(module, log_base2k, log_q);
let bytes_of_enc_sk: usize = encrypt_rlwe_sk_tmp_bytes(module, log_base2k, log_q);
let (tmp_bytes_pt, tmp_bytes) = tmp_bytes.split_at_mut(bytes_of_pt);
let (tmp_bytes_enc_sk, tmp_bytes) = tmp_bytes.split_at_mut(bytes_of_enc_sk);
let (tmp_bytes_elem, tmp_bytes_vmp_prepare_row) = tmp_bytes.split_at_mut(bytes_of_elem);
let mut tmp_elem: Elem<VecZnx> = Elem::<VecZnx>::from_bytes_borrow(module, log_base2k, log_q, 2, tmp_bytes_elem);
let mut tmp_pt: Plaintext = Plaintext::from_bytes_borrow(module, log_base2k, log_q, tmp_bytes_pt);
(0..rows).for_each(|row_i| {
// Sets the i-th row of the RLWE sample to m (i.e. m * 2^{-log_base2k*i})
tmp_pt.at_mut(0).at_mut(row_i).copy_from_slice(&m.raw());
// Encrypts RLWE(m * 2^{-log_base2k*i})
encrypt_rlwe_sk_core::<PT_POS>(
module,
&mut tmp_elem,
Some(tmp_pt.at(0)),
sk,
source_xa,
source_xe,
sigma,
tmp_bytes_enc_sk,
);
// Zeroes the ith-row of tmp_pt
tmp_pt.at_mut(0).at_mut(row_i).fill(0);
// GRLWE[row_i][0||1] = [-as + m * 2^{-i*log_base2k} + e*2^{-log_q} || a]
module.vmp_prepare_row(
ct[0],
tmp_elem.at(0).raw(),
row_i,
tmp_bytes_vmp_prepare_row,
);
module.vmp_prepare_row(
&mut ct[1],
tmp_elem.at(1).raw(),
row_i,
tmp_bytes_vmp_prepare_row,
);
});
}