1use std::time::Instant;
  2
  3use backend::{MatZnxDftOps, MatZnxDftScratch, Module, ScalarZnxDftOps, Scratch, VecZnxDftOps, VecZnxOps, ZnxView, ZnxViewMut, ZnxZero, FFT64};
  4use itertools::izip;
  5
  6use crate::{
  7    blind_rotation::key::BlindRotationKeyCGGI, lwe::ciphertext::LWECiphertextToRef, FourierGLWESecret, GGSWCiphertext, GLWECiphertext, GLWECiphertextToMut, GLWECiphertextToRef, GLWEPlaintext, GLWESecret, Infos, LWECiphertext, LWESecret, ScratchCore
  8};
  9
 10pub fn cggi_blind_rotate_scratch_space(
 11    module: &Module<FFT64>,
 12    basek: usize,
 13    k_lut: usize,
 14    k_brk: usize,
 15    rows: usize,
 16    rank: usize,
 17) -> usize {
 18    let size = k_brk.div_ceil(basek);
 19    GGSWCiphertext::<Vec<u8>, FFT64>::bytes_of(module, basek, k_brk, rows, 1, rank)
 20        + (module.mat_znx_dft_mul_x_pow_minus_one_scratch_space(size, rank + 1)
 21            | GLWECiphertext::external_product_inplace_scratch_space(module, basek, k_lut, k_brk, 1, rank))
 22}
 23
 24pub fn cggi_blind_rotate<DataRes, DataIn, DataLUT>(
 25    module: &Module<FFT64>,
 26    res: &mut GLWECiphertext<DataRes>,
 27    lwe: &LWECiphertext<DataIn>,
 28    lut: &GLWEPlaintext<DataLUT>,
 29    brk: &BlindRotationKeyCGGI<FFT64>,
 30    scratch: &mut Scratch,
 31) where
 32    DataRes: AsRef<[u8]> + AsMut<[u8]>,
 33    DataIn: AsRef<[u8]>,
 34    DataLUT: AsRef<[u8]>,
 35{
 36    let basek = res.basek();
 37
 38    let mut lwe_2n: Vec<i64> = vec![0i64; lwe.n() + 1]; // TODO: from scratch space
 39    let mut out_mut: GLWECiphertext<&mut [u8]> = res.to_mut();
 40    let lwe_ref: LWECiphertext<&[u8]> = lwe.to_ref();
 41    let lut_ref: GLWECiphertext<&[u8]> = lut.to_ref();
 42
 43    let cols = out_mut.rank()+1;
 44
 45    mod_switch_2n(module, &mut lwe_2n, &lwe_ref);
 46
 47    let a: &[i64] = &lwe_2n[1..];
 48    let b: i64 = lwe_2n[0];
 49
 50    out_mut.data.zero();
 51
 52    // Initialize out to X^{b} * LUT(X)
 53    module.vec_znx_rotate(b, &mut out_mut.data, 0, &lut_ref.data, 0);
 54
 55    let block_size: usize = brk.block_size();
 56
 57    // ACC + [sum DFT(X^ai -1) * (DFT(ACC) x BRKi)]
 58
 59    let (mut acc_dft, scratch1) = scratch.tmp_glwe_fourier(module, brk.basek(), out_mut.k(), out_mut.rank());
 60    let (mut acc_add_dft, scratch2) = scratch1.tmp_glwe_fourier(module, brk.basek(), out_mut.k(), out_mut.rank());
 61    let (mut vmp_res, scratch3) = scratch2.tmp_glwe_fourier(module, basek, out_mut.k(), out_mut.rank());
 62    let (mut xai_minus_one, scratch4) = scratch3.tmp_scalar_znx(module, 1);
 63    let (mut xai_minus_one_dft, scratch5) = scratch4.tmp_scalar_znx_dft(module, 1);
 64
 65    let start: Instant = Instant::now();
 66    izip!(
 67        a.chunks_exact(block_size),
 68        brk.data.chunks_exact(block_size)
 69    )
 70    .for_each(|(ai, ski)| {
 71
 72        out_mut.dft(module, &mut acc_dft);
 73        acc_add_dft.data.zero();
 74
 75        izip!(ai.iter(), ski.iter())
 76            .enumerate()
 77            .for_each(|(i, (aii, skii))| {
 78
 79                // vmp_res = DFT(acc) * BRK[i]
 80                module.vmp_apply(&mut vmp_res.data, &acc_dft.data, &skii.data, scratch5);
 81
 82                // DFT(X^ai -1)
 83                xai_minus_one.zero();
 84                xai_minus_one.at_mut(0, 0)[0] = 1;
 85                module.vec_znx_rotate_inplace(*aii, &mut xai_minus_one, 0);
 86                xai_minus_one.at_mut(0, 0)[0] -= 1;
 87                module.svp_prepare(&mut xai_minus_one_dft, 0, &xai_minus_one, 0);
 88
 89                // DFT(X^ai -1) * (DFT(acc) * BRK[i])
 90                (0..cols).for_each(|i|{
 91                    module.svp_apply_inplace(&mut vmp_res.data, i, &xai_minus_one_dft, 0);
 92                    module.vec_znx_dft_add_inplace(&mut acc_add_dft.data, i, &vmp_res.data, i);
 93                });
 94            });
 95        
 96        (0..cols).for_each(|i|{
 97            module.vec_znx_dft_add_inplace(&mut acc_dft.data, i, &acc_add_dft.data, i);
 98        });
 99        
100        acc_dft.idft(module, &mut out_mut, scratch5);
101
102    });
103    let duration: std::time::Duration = start.elapsed();
104    println!("external products: {} us", duration.as_micros());
105}
106
107pub(crate) fn mod_switch_2n(module: &Module<FFT64>, res: &mut [i64], lwe: &LWECiphertext<&[u8]>) {
108    let basek: usize = lwe.basek();
109
110    let log2n: usize = module.log_n() + 1;
111
112    res.copy_from_slice(&lwe.data.at(0, 0));
113
114    if basek > log2n {
115        let diff: usize = basek - log2n;
116        res.iter_mut().for_each(|x| {
117            *x = div_signed_by_pow2(x, diff);
118        })
119    } else {
120        let rem: usize = basek - (log2n % basek);
121        let size: usize = log2n.div_ceil(basek);
122        (1..size).for_each(|i| {
123            if i == size - 1 && rem != basek {
124                let k_rem: usize = basek - rem;
125                izip!(lwe.data.at(0, i).iter(), res.iter_mut()).for_each(|(x, y)| {
126                    *y = (*y << k_rem) + (x >> rem);
127                });
128            } else {
129                izip!(lwe.data.at(0, i).iter(), res.iter_mut()).for_each(|(x, y)| {
130                    *y = (*y << basek) + x;
131                });
132            }
133        })
134    }
135}
136
137#[inline(always)]
138fn div_signed_by_pow2(x: &i64, k: usize) -> i64 {
139    let bias: i64 = (1 << k) - 1;
140    (x + ((x >> 63) & bias)) >> k
141}