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