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export blind rotation
This commit is contained in:
Jean-Philippe Bossuat
463
core/src/blind_rotation/cggi.rs
Normal file
463
core/src/blind_rotation/cggi.rs
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@@ -0,0 +1,463 @@
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use backend::{
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FFT64, MatZnxDftOps, MatZnxDftScratch, Module, ScalarZnx, ScalarZnxAlloc, ScalarZnxDft, ScalarZnxDftAlloc, ScalarZnxDftOps,
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Scratch, VecZnxAlloc, VecZnxBigAlloc, VecZnxBigOps, VecZnxBigScratch, VecZnxDftAlloc, VecZnxDftOps, VecZnxOps, ZnxView,
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ZnxViewMut, ZnxZero,
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};
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use itertools::izip;
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use crate::{
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GLWECiphertext, GLWECiphertextToMut, GLWEOps, Infos, LWECiphertext, ScratchCore,
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blind_rotation::{key::BlindRotationKeyCGGI, lut::LookUpTable},
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dist::Distribution,
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lwe::ciphertext::LWECiphertextToRef,
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};
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pub fn cggi_blind_rotate_scratch_space(
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module: &Module<FFT64>,
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block_size: usize,
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extension_factor: usize,
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basek: usize,
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k_res: usize,
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k_brk: usize,
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rows: usize,
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rank: usize,
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) -> usize {
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let brk_size: usize = k_brk.div_ceil(basek);
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if block_size > 1 {
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let cols: usize = rank + 1;
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let acc_dft: usize = module.bytes_of_vec_znx_dft(cols, rows) * extension_factor;
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let acc_big: usize = module.bytes_of_vec_znx_big(1, brk_size);
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let vmp_res: usize = module.bytes_of_vec_znx_dft(cols, brk_size) * extension_factor;
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let acc_dft_add: usize = vmp_res;
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let xai_plus_y: usize = module.bytes_of_scalar_znx(1);
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let xai_plus_y_dft: usize = module.bytes_of_scalar_znx_dft(1);
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let vmp: usize = module.vmp_apply_tmp_bytes(brk_size, rows, rows, 2, 2, brk_size); // GGSW product: (1 x 2) x (2 x 2)
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let acc: usize;
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if extension_factor > 1 {
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acc = module.bytes_of_vec_znx(cols, k_res.div_ceil(basek)) * extension_factor;
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} else {
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acc = 0;
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}
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return acc
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+ acc_dft
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+ acc_dft_add
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+ vmp_res
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+ xai_plus_y
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+ xai_plus_y_dft
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+ (vmp | (acc_big + (module.vec_znx_big_normalize_tmp_bytes() | module.vec_znx_idft_tmp_bytes())));
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} else {
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2 * GLWECiphertext::bytes_of(module, basek, k_res, rank)
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+ GLWECiphertext::external_product_scratch_space(module, basek, k_res, k_res, k_brk, 1, rank)
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}
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}
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pub fn cggi_blind_rotate<DataRes, DataIn>(
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module: &Module<FFT64>,
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res: &mut GLWECiphertext<DataRes>,
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lwe: &LWECiphertext<DataIn>,
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lut: &LookUpTable,
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brk: &BlindRotationKeyCGGI<FFT64>,
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scratch: &mut Scratch,
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) where
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DataRes: AsRef<[u8]> + AsMut<[u8]>,
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DataIn: AsRef<[u8]>,
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{
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match brk.dist {
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Distribution::BinaryBlock(_) | Distribution::BinaryFixed(_) | Distribution::BinaryProb(_) | Distribution::ZERO => {
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if lut.extension_factor() > 1 {
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cggi_blind_rotate_block_binary_extended(module, res, lwe, lut, brk, scratch);
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} else if brk.block_size() > 1 {
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cggi_blind_rotate_block_binary(module, res, lwe, lut, brk, scratch);
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} else {
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cggi_blind_rotate_binary_standard(module, res, lwe, lut, brk, scratch);
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}
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}
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// TODO: ternary distribution ?
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_ => panic!(
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"invalid BlindRotationKeyCGGI distribution: must be BinaryBlock, BinaryFixed or BinaryProb (or ZERO for debugging)"
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),
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}
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}
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pub(crate) fn cggi_blind_rotate_block_binary_extended<DataRes, DataIn>(
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module: &Module<FFT64>,
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res: &mut GLWECiphertext<DataRes>,
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lwe: &LWECiphertext<DataIn>,
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lut: &LookUpTable,
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brk: &BlindRotationKeyCGGI<FFT64>,
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scratch: &mut Scratch,
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) where
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DataRes: AsRef<[u8]> + AsMut<[u8]>,
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DataIn: AsRef<[u8]>,
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{
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let extension_factor: usize = lut.extension_factor();
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let basek: usize = res.basek();
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let rows: usize = brk.rows();
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let cols: usize = res.rank() + 1;
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let (mut acc, scratch1) = scratch.tmp_slice_vec_znx(extension_factor, module, cols, res.size());
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let (mut acc_dft, scratch2) = scratch1.tmp_slice_vec_znx_dft(extension_factor, module, cols, rows);
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let (mut vmp_res, scratch3) = scratch2.tmp_slice_vec_znx_dft(extension_factor, module, cols, brk.size());
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let (mut acc_add_dft, scratch4) = scratch3.tmp_slice_vec_znx_dft(extension_factor, module, cols, brk.size());
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let (mut xai_plus_y, scratch5) = scratch4.tmp_scalar_znx(module, 1);
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let (mut xai_plus_y_dft, scratch6) = scratch5.tmp_scalar_znx_dft(module, 1);
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(0..extension_factor).for_each(|i| {
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acc[i].zero();
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});
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let mut lwe_2n: Vec<i64> = vec![0i64; lwe.n() + 1]; // TODO: from scratch space
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let lwe_ref: LWECiphertext<&[u8]> = lwe.to_ref();
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let two_n_ext: usize = 2 * lut.domain_size();
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negate_and_mod_switch_2n(two_n_ext, &mut lwe_2n, &lwe_ref);
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let a: &[i64] = &lwe_2n[1..];
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let b_pos: usize = ((lwe_2n[0] + two_n_ext as i64) % two_n_ext as i64) as usize;
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let b_hi: usize = b_pos / extension_factor;
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let b_lo: usize = b_pos % extension_factor;
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for (i, j) in (0..b_lo).zip(extension_factor - b_lo..extension_factor) {
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module.vec_znx_rotate(b_hi as i64 + 1, &mut acc[i], 0, &lut.data[j], 0);
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}
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for (i, j) in (b_lo..extension_factor).zip(0..extension_factor - b_lo) {
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module.vec_znx_rotate(b_hi as i64, &mut acc[i], 0, &lut.data[j], 0);
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}
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let block_size: usize = brk.block_size();
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izip!(
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a.chunks_exact(block_size),
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brk.data.chunks_exact(block_size)
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)
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.for_each(|(ai, ski)| {
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(0..extension_factor).for_each(|i| {
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(0..cols).for_each(|j| {
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module.vec_znx_dft(1, 0, &mut acc_dft[i], j, &acc[i], j);
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});
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acc_add_dft[i].zero();
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});
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// TODO: first & last iterations can be optimized
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izip!(ai.iter(), ski.iter()).for_each(|(aii, skii)| {
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let ai_pos: usize = ((aii + two_n_ext as i64) % two_n_ext as i64) as usize;
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let ai_hi: usize = ai_pos / extension_factor;
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let ai_lo: usize = ai_pos % extension_factor;
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// vmp_res = DFT(acc) * BRK[i]
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(0..extension_factor).for_each(|i| {
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module.vmp_apply(&mut vmp_res[i], &acc_dft[i], &skii.data, scratch6);
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});
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// Trivial case: no rotation between polynomials, we can directly multiply with (X^{-ai} - 1)
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if ai_lo == 0 {
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// DFT X^{-ai}
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set_xai_plus_y(module, ai_hi, -1, &mut xai_plus_y_dft, &mut xai_plus_y);
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// Sets acc_add_dft[i] = (acc[i] * sk) * (X^{-ai} - 1)
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(0..extension_factor).for_each(|j| {
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(0..cols).for_each(|i| {
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module.svp_apply_inplace(&mut vmp_res[j], i, &xai_plus_y_dft, 0);
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module.vec_znx_dft_add_inplace(&mut acc_add_dft[j], i, &vmp_res[j], i);
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});
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});
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// Non trivial case: rotation between polynomials
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// In this case we can't directly multiply with (X^{-ai} - 1) because of the
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// ring homomorphism R^{N} -> prod R^{N/extension_factor}, so we split the
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// computation in two steps: acc_add_dft = (acc * sk) * (-1) + (acc * sk) * X^{-ai}
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} else {
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// Sets acc_add_dft[i] = acc[i] * sk
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(0..extension_factor).for_each(|i| {
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(0..cols).for_each(|k| {
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module.vec_znx_dft_sub_ab_inplace(&mut acc_add_dft[i], k, &vmp_res[i], k);
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})
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});
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// DFT X^{-ai}
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set_xai_plus_y(module, ai_hi + 1, 0, &mut xai_plus_y_dft, &mut xai_plus_y);
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// Sets acc_add_dft[0..ai_lo] += (acc[extension_factor - ai_lo..extension_factor] * sk) * X^{-ai+1}
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for (i, j) in (0..ai_lo).zip(extension_factor - ai_lo..extension_factor) {
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(0..cols).for_each(|k| {
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module.svp_apply_inplace(&mut vmp_res[j], k, &xai_plus_y_dft, 0);
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module.vec_znx_dft_add_inplace(&mut acc_add_dft[i], k, &vmp_res[j], k);
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});
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}
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// DFT X^{-ai}
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set_xai_plus_y(module, ai_hi, 0, &mut xai_plus_y_dft, &mut xai_plus_y);
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// Sets acc_add_dft[ai_lo..extension_factor] += (acc[0..extension_factor - ai_lo] * sk) * X^{-ai}
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for (i, j) in (ai_lo..extension_factor).zip(0..extension_factor - ai_lo) {
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(0..cols).for_each(|k| {
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module.svp_apply_inplace(&mut vmp_res[j], k, &xai_plus_y_dft, 0);
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module.vec_znx_dft_add_inplace(&mut acc_add_dft[i], k, &vmp_res[j], k);
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});
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}
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}
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});
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{
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let (mut acc_add_big, scratch7) = scratch6.tmp_vec_znx_big(module, 1, brk.size());
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(0..extension_factor).for_each(|j| {
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(0..cols).for_each(|i| {
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module.vec_znx_idft(&mut acc_add_big, 0, &acc_add_dft[j], i, scratch7);
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module.vec_znx_big_add_small_inplace(&mut acc_add_big, 0, &acc[j], i);
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module.vec_znx_big_normalize(basek, &mut acc[j], i, &acc_add_big, 0, scratch7);
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});
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});
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}
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});
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(0..cols).for_each(|i| {
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module.vec_znx_copy(&mut res.data, i, &acc[0], i);
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});
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}
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fn set_xai_plus_y(
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module: &Module<FFT64>,
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ai: usize,
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y: i64,
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res: &mut ScalarZnxDft<&mut [u8], FFT64>,
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buf: &mut ScalarZnx<&mut [u8]>,
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) {
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let n: usize = module.n();
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{
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let raw: &mut [i64] = buf.at_mut(0, 0);
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if ai < n {
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raw[ai] = 1;
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} else {
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raw[(ai - n) & (n - 1)] = -1;
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}
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raw[0] += y;
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}
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module.svp_prepare(res, 0, buf, 0);
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{
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let raw: &mut [i64] = buf.at_mut(0, 0);
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if ai < n {
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raw[ai] = 0;
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} else {
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raw[(ai - n) & (n - 1)] = 0;
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}
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raw[0] = 0;
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}
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}
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pub(crate) fn cggi_blind_rotate_block_binary<DataRes, DataIn>(
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module: &Module<FFT64>,
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res: &mut GLWECiphertext<DataRes>,
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lwe: &LWECiphertext<DataIn>,
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lut: &LookUpTable,
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brk: &BlindRotationKeyCGGI<FFT64>,
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scratch: &mut Scratch,
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) where
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DataRes: AsRef<[u8]> + AsMut<[u8]>,
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DataIn: AsRef<[u8]>,
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{
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let mut lwe_2n: Vec<i64> = vec![0i64; lwe.n() + 1]; // TODO: from scratch space
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let mut out_mut: GLWECiphertext<&mut [u8]> = res.to_mut();
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let lwe_ref: LWECiphertext<&[u8]> = lwe.to_ref();
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let two_n: usize = module.n() << 1;
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let basek: usize = brk.basek();
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let rows = brk.rows();
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let cols: usize = out_mut.rank() + 1;
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negate_and_mod_switch_2n(2 * lut.domain_size(), &mut lwe_2n, &lwe_ref);
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let a: &[i64] = &lwe_2n[1..];
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let b: i64 = lwe_2n[0];
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out_mut.data.zero();
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// Initialize out to X^{b} * LUT(X)
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module.vec_znx_rotate(b, &mut out_mut.data, 0, &lut.data[0], 0);
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let block_size: usize = brk.block_size();
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// ACC + [sum DFT(X^ai -1) * (DFT(ACC) x BRKi)]
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let (mut acc_dft, scratch1) = scratch.tmp_vec_znx_dft(module, cols, rows);
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let (mut vmp_res, scratch2) = scratch1.tmp_vec_znx_dft(module, cols, brk.size());
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let (mut acc_add_dft, scratch3) = scratch2.tmp_vec_znx_dft(module, cols, brk.size());
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let (mut xai_plus_y, scratch4) = scratch3.tmp_scalar_znx(module, 1);
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let (mut xai_plus_y_dft, scratch5) = scratch4.tmp_scalar_znx_dft(module, 1);
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izip!(
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a.chunks_exact(block_size),
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brk.data.chunks_exact(block_size)
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)
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.for_each(|(ai, ski)| {
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(0..cols).for_each(|j| {
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module.vec_znx_dft(1, 0, &mut acc_dft, j, &out_mut.data, j);
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});
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acc_add_dft.zero();
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izip!(ai.iter(), ski.iter()).for_each(|(aii, skii)| {
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let ai_pos: usize = ((aii + two_n as i64) % two_n as i64) as usize;
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// vmp_res = DFT(acc) * BRK[i]
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module.vmp_apply(&mut vmp_res, &acc_dft, &skii.data, scratch5);
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// DFT(X^ai -1)
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set_xai_plus_y(module, ai_pos, -1, &mut xai_plus_y_dft, &mut xai_plus_y);
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// DFT(X^ai -1) * (DFT(acc) * BRK[i])
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(0..cols).for_each(|i| {
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module.svp_apply_inplace(&mut vmp_res, i, &xai_plus_y_dft, 0);
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module.vec_znx_dft_add_inplace(&mut acc_add_dft, i, &vmp_res, i);
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});
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});
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(0..cols).for_each(|i| {
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module.vec_znx_dft_add_inplace(&mut acc_dft, i, &acc_add_dft, i);
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});
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{
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let (mut acc_add_big, scratch6) = scratch5.tmp_vec_znx_big(module, 1, brk.size());
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(0..cols).for_each(|i| {
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module.vec_znx_idft(&mut acc_add_big, 0, &acc_add_dft, i, scratch6);
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module.vec_znx_big_add_small_inplace(&mut acc_add_big, 0, &out_mut.data, i);
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module.vec_znx_big_normalize(basek, &mut out_mut.data, i, &acc_add_big, 0, scratch6);
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});
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}
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});
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}
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pub(crate) fn cggi_blind_rotate_binary_standard<DataRes, DataIn>(
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module: &Module<FFT64>,
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res: &mut GLWECiphertext<DataRes>,
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lwe: &LWECiphertext<DataIn>,
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lut: &LookUpTable,
|
||||
brk: &BlindRotationKeyCGGI<FFT64>,
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scratch: &mut Scratch,
|
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) where
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DataRes: AsRef<[u8]> + AsMut<[u8]>,
|
||||
DataIn: AsRef<[u8]>,
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||||
{
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||||
#[cfg(debug_assertions)]
|
||||
{
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assert_eq!(
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res.n(),
|
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module.n(),
|
||||
"res.n(): {} != brk.n(): {}",
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res.n(),
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module.n()
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);
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assert_eq!(
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lut.domain_size(),
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module.n(),
|
||||
"lut.n(): {} != brk.n(): {}",
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lut.domain_size(),
|
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module.n()
|
||||
);
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assert_eq!(
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brk.n(),
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module.n(),
|
||||
"brk.n(): {} != brk.n(): {}",
|
||||
brk.n(),
|
||||
module.n()
|
||||
);
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||||
assert_eq!(
|
||||
res.rank(),
|
||||
brk.rank(),
|
||||
"res.rank(): {} != brk.rank(): {}",
|
||||
res.rank(),
|
||||
brk.rank()
|
||||
);
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||||
assert_eq!(
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lwe.n(),
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||||
brk.data.len(),
|
||||
"lwe.n(): {} != brk.data.len(): {}",
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||||
lwe.n(),
|
||||
brk.data.len()
|
||||
);
|
||||
}
|
||||
|
||||
let mut lwe_2n: Vec<i64> = vec![0i64; lwe.n() + 1]; // TODO: from scratch space
|
||||
let mut out_mut: GLWECiphertext<&mut [u8]> = res.to_mut();
|
||||
let lwe_ref: LWECiphertext<&[u8]> = lwe.to_ref();
|
||||
let basek: usize = brk.basek();
|
||||
|
||||
negate_and_mod_switch_2n(2 * lut.domain_size(), &mut lwe_2n, &lwe_ref);
|
||||
|
||||
let a: &[i64] = &lwe_2n[1..];
|
||||
let b: i64 = lwe_2n[0];
|
||||
|
||||
out_mut.data.zero();
|
||||
|
||||
// Initialize out to X^{b} * LUT(X)
|
||||
module.vec_znx_rotate(b, &mut out_mut.data, 0, &lut.data[0], 0);
|
||||
|
||||
// ACC + [sum DFT(X^ai -1) * (DFT(ACC) x BRKi)]
|
||||
let (mut acc_tmp, scratch1) = scratch.tmp_glwe_ct(module, basek, out_mut.k(), out_mut.rank());
|
||||
let (mut acc_tmp_rot, scratch2) = scratch1.tmp_glwe_ct(module, basek, out_mut.k(), out_mut.rank());
|
||||
|
||||
// TODO: see if faster by skipping normalization in external product and keeping acc in big coeffs
|
||||
// TODO: first iteration can be optimized to be a gglwe product
|
||||
izip!(a.iter(), brk.data.iter()).for_each(|(ai, ski)| {
|
||||
// acc_tmp = sk[i] * acc
|
||||
acc_tmp.external_product(module, &out_mut, ski, scratch2);
|
||||
|
||||
// acc_tmp = (sk[i] * acc) * X^{ai}
|
||||
acc_tmp_rot.rotate(module, *ai, &acc_tmp);
|
||||
|
||||
// acc = acc + (sk[i] * acc) * X^{ai}
|
||||
out_mut.add_inplace(module, &acc_tmp_rot);
|
||||
|
||||
// acc = acc + (sk[i] * acc) * X^{ai} - (sk[i] * acc) = acc + (sk[i] * acc) * (X^{ai} - 1)
|
||||
out_mut.sub_inplace_ab(module, &acc_tmp);
|
||||
});
|
||||
|
||||
// We can normalize only at the end because we add normalized values in [-2^{basek-1}, 2^{basek-1}]
|
||||
// on top of each others, thus ~ 2^{63-basek} additions are supported before overflow.
|
||||
out_mut.normalize_inplace(module, scratch2);
|
||||
}
|
||||
|
||||
pub(crate) fn negate_and_mod_switch_2n(n: usize, res: &mut [i64], lwe: &LWECiphertext<&[u8]>) {
|
||||
let basek: usize = lwe.basek();
|
||||
|
||||
let log2n: usize = usize::BITS as usize - (n - 1).leading_zeros() as usize + 1;
|
||||
|
||||
res.copy_from_slice(&lwe.data.at(0, 0));
|
||||
res.iter_mut().for_each(|x| *x = -*x);
|
||||
|
||||
if basek > log2n {
|
||||
let diff: usize = basek - log2n;
|
||||
res.iter_mut().for_each(|x| {
|
||||
*x = div_round_by_pow2(x, diff);
|
||||
})
|
||||
} else {
|
||||
let rem: usize = basek - (log2n % basek);
|
||||
let size: usize = log2n.div_ceil(basek);
|
||||
(1..size).for_each(|i| {
|
||||
if i == size - 1 && rem != basek {
|
||||
let k_rem: usize = basek - rem;
|
||||
izip!(lwe.data.at(0, i).iter(), res.iter_mut()).for_each(|(x, y)| {
|
||||
*y = (*y << k_rem) + (x >> rem);
|
||||
});
|
||||
} else {
|
||||
izip!(lwe.data.at(0, i).iter(), res.iter_mut()).for_each(|(x, y)| {
|
||||
*y = (*y << basek) + x;
|
||||
});
|
||||
}
|
||||
})
|
||||
}
|
||||
}
|
||||
|
||||
#[inline(always)]
|
||||
fn div_round_by_pow2(x: &i64, k: usize) -> i64 {
|
||||
(x + (1 << (k - 1))) >> k
|
||||
}
|
||||
Reference in New Issue
Block a user