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https://github.com/arnaucube/poulpy.git
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76 lines
2.8 KiB
Rust
76 lines
2.8 KiB
Rust
use crate::{
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ciphertext::{Ciphertext, GadgetCiphertext},
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elem::Elem,
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};
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use base2k::{Infos, Module, VecZnx, VecZnxBig, VecZnxDft, VmpPMatOps};
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pub fn gadget_product_tmp_bytes(
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module: &Module,
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log_base2k: usize,
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out_log_q: usize,
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in_log_q: usize,
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gct_rows: usize,
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gct_log_q: usize,
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) -> usize {
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let gct_cols: usize = (gct_log_q + log_base2k - 1) / log_base2k;
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let in_limbs: usize = (in_log_q + log_base2k - 1) / log_base2k;
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let out_limbs: usize = (out_log_q + log_base2k - 1) / log_base2k;
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module.vmp_apply_dft_to_dft_tmp_bytes(out_limbs, in_limbs, gct_rows, gct_cols)
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+ 2 * module.bytes_of_vec_znx_dft(gct_cols)
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}
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/// Evaluates the gadget product res <- a x b.
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///
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/// # Arguments
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///
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/// * `module`: backend support for operations mod (X^N + 1)
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/// * `res`: an [Elem] to store (-cs + m * a + e, c) with res_ncols limbs.
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/// * `a`: a [VecZnx] of a_ncols limbs.
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/// * `b`: a [GadgetCiphertext] as a vector of (-Bs + m * 2^{-k} + E, B)
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/// containing b_nrows [VecZnx], each of b_ncols limbs.
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///
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/// # Computation
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///
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/// res = sum[min(a_ncols, b_nrows)] decomp(a, i) * (-B[i]s + m * 2^{-k*i} + E[i], B[i])
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/// = (cs + m * a + e, c) with min(res_limbs, b_cols) limbs.
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pub fn gadget_product_thread_safe(
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module: &Module,
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res: &mut Elem,
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a: &VecZnx,
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b: &GadgetCiphertext,
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tmp_bytes: &mut [u8],
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) {
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let log_base2k: usize = b.log_base2k();
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let cols: usize = b.cols();
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let (tmp_bytes_vmp_apply_dft, tmp_bytes) =
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tmp_bytes.split_at_mut(module.bytes_of_vec_znx_dft(cols));
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let (tmp_bytes_c1_dft, tmp_bytes_res_dft) = tmp_bytes.split_at_mut(tmp_bytes.len() >> 1);
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let mut c1_dft: VecZnxDft = module.new_vec_znx_from_bytes(cols, tmp_bytes_c1_dft);
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let mut res_dft: VecZnxDft = module.new_vec_znx_from_bytes(cols, tmp_bytes_res_dft);
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let mut res_big: VecZnxBig = res_dft.as_vec_znx_big();
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// c1_dft <- DFT(c1) [cols]
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module.vec_znx_dft(&mut c1_dft, a, a.limbs());
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// res_dft <- sum[rows] DFT(c1)[cols] x GadgetCiphertext[0][cols]
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module.vmp_apply_dft_to_dft(&mut res_dft, &c1_dft, &b.value[0], tmp_bytes_vmp_apply_dft);
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// res_big <- IDFT(DFT(c1) x GadgetCiphertext[0])
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module.vec_znx_idft_tmp_a(&mut res_big, &mut res_dft, cols);
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// res[0] = normalize(c0 + c1_dft x GadgetCiphertext[0])
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module.vec_znx_big_normalize(log_base2k, res.at_mut(0), &res_big, tmp_bytes_vmp_apply_dft);
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// res_dft <- DFT(c1) x GadgetCiphertext[1]
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module.vmp_apply_dft_to_dft(&mut res_dft, &c1_dft, &b.value[1], tmp_bytes_vmp_apply_dft);
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// res_big <- IDFT(DFT(c1) x GadgetCiphertext[1])
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module.vec_znx_idft_tmp_a(&mut res_big, &mut res_dft, cols);
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// res[1] = normalize(c1_dft x GadgetCiphertext[1])
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module.vec_znx_big_normalize(log_base2k, res.at_mut(1), &res_big, tmp_bytes_vmp_apply_dft);
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}
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