poulpy/poulpy-core/src/tests/test_suite/packing.rs

use std::collections::HashMap;

use poulpy_hal::{
    api::{ScratchAvailable, ScratchOwnedAlloc, ScratchOwnedBorrow},
    layouts::{Backend, Module, Scratch, ScratchOwned},
    source::Source,
};

use crate::{
    AutomorphismKeyEncryptSk, GLWEDecrypt, GLWEEncryptSk, GLWEPacker, GLWEPacking, GLWERotate, GLWESub, ScratchTakeCore,
    layouts::{
        AutomorphismKey, AutomorphismKeyLayout, GLWE, GLWEAutomorphismKeyPreparedApi, GLWELayout, GLWEPlaintext, GLWESecret,
        GLWESecretPreparedApi,
        prepared::{GLWEAutomorphismKeyPrepared, GLWESecretPrepared},
    },
};

pub fn test_glwe_packing<BE: Backend>(module: &Module<BE>)
where
    Module<BE>: GLWEEncryptSk<BE>
        + AutomorphismKeyEncryptSk<BE>
        + GLWEAutomorphismKeyPreparedApi<BE>
        + GLWEPacking<BE>
        + GLWESecretPreparedApi<BE>
        + GLWESub
        + GLWEDecrypt<BE>
        + GLWERotate<BE>,
    ScratchOwned<BE>: ScratchOwnedAlloc<BE> + ScratchOwnedBorrow<BE>,
    Scratch<BE>: ScratchAvailable + ScratchTakeCore<BE>,
{
    let mut source_xs: Source = Source::new([0u8; 32]);
    let mut source_xe: Source = Source::new([0u8; 32]);
    let mut source_xa: Source = Source::new([0u8; 32]);

    let n: usize = module.n();
    let base2k: usize = 18;
    let k_ct: usize = 36;
    let pt_k: usize = 18;
    let rank: usize = 3;
    let dsize: usize = 1;
    let k_ksk: usize = k_ct + base2k * dsize;

    let dnum: usize = k_ct.div_ceil(base2k * dsize);

    let glwe_out_infos: GLWELayout = GLWELayout {
        n: n.into(),
        base2k: base2k.into(),
        k: k_ct.into(),
        rank: rank.into(),
    };

    let key_infos: AutomorphismKeyLayout = AutomorphismKeyLayout {
        n: n.into(),
        base2k: base2k.into(),
        k: k_ksk.into(),
        rank: rank.into(),
        dsize: dsize.into(),
        dnum: dnum.into(),
    };

    let mut scratch: ScratchOwned<BE> = ScratchOwned::alloc(
        GLWE::encrypt_sk_tmp_bytes(module, &glwe_out_infos)
            | AutomorphismKey::encrypt_sk_tmp_bytes(module, &key_infos)
            | GLWEPacker::tmp_bytes(module, &glwe_out_infos, &key_infos),
    );

    let mut sk: GLWESecret<Vec<u8>> = GLWESecret::alloc_from_infos(&glwe_out_infos);
    sk.fill_ternary_prob(0.5, &mut source_xs);

    let mut sk_dft: GLWESecretPrepared<Vec<u8>, BE> = GLWESecretPrepared::alloc_from_infos(module, &sk);
    sk_dft.prepare(module, &sk);

    let mut pt: GLWEPlaintext<Vec<u8>> = GLWEPlaintext::alloc_from_infos(&glwe_out_infos);
    let mut data: Vec<i64> = vec![0i64; n];
    data.iter_mut().enumerate().for_each(|(i, x)| {
        *x = i as i64;
    });

    pt.encode_vec_i64(&data, pt_k.into());

    let gal_els: Vec<i64> = GLWEPacker::galois_elements(module);

    let mut auto_keys: HashMap<i64, GLWEAutomorphismKeyPrepared<Vec<u8>, BE>> = HashMap::new();
    let mut tmp: AutomorphismKey<Vec<u8>> = AutomorphismKey::alloc_from_infos(&key_infos);
    gal_els.iter().for_each(|gal_el| {
        tmp.encrypt_sk(
            module,
            *gal_el,
            &sk,
            &mut source_xa,
            &mut source_xe,
            scratch.borrow(),
        );
        let mut atk_prepared: GLWEAutomorphismKeyPrepared<Vec<u8>, BE> =
            GLWEAutomorphismKeyPrepared::alloc_from_infos(module, &tmp);
        atk_prepared.prepare(module, &tmp, scratch.borrow());
        auto_keys.insert(*gal_el, atk_prepared);
    });

    let log_batch: usize = 0;

    let mut packer: GLWEPacker = GLWEPacker::alloc(&glwe_out_infos, log_batch);

    let mut ct: GLWE<Vec<u8>> = GLWE::alloc_from_infos(&glwe_out_infos);

    ct.encrypt_sk(
        module,
        &pt,
        &sk_dft,
        &mut source_xa,
        &mut source_xe,
        scratch.borrow(),
    );

    let log_n: usize = module.log_n();

    (0..n >> log_batch).for_each(|i| {
        ct.encrypt_sk(
            module,
            &pt,
            &sk_dft,
            &mut source_xa,
            &mut source_xe,
            scratch.borrow(),
        );

        module.glwe_rotate_inplace(-(1 << log_batch), &mut pt, scratch.borrow()); // X^-batch * pt

        if reverse_bits_msb(i, log_n as u32).is_multiple_of(5) {
            packer.add(module, Some(&ct), &auto_keys, scratch.borrow());
        } else {
            packer.add(module, None::<&GLWE<Vec<u8>>>, &auto_keys, scratch.borrow())
        }
    });

    let mut res: GLWE<Vec<u8>> = GLWE::alloc_from_infos(&glwe_out_infos);
    packer.flush(module, &mut res);

    let mut pt_want: GLWEPlaintext<Vec<u8>> = GLWEPlaintext::alloc_from_infos(&glwe_out_infos);
    let mut data: Vec<i64> = vec![0i64; n];
    data.iter_mut().enumerate().for_each(|(i, x)| {
        if i.is_multiple_of(5) {
            *x = reverse_bits_msb(i, log_n as u32) as i64;
        }
    });

    pt_want.encode_vec_i64(&data, pt_k.into());

    res.decrypt(module, &mut pt, &sk_dft, scratch.borrow());

    module.glwe_sub_inplace(&mut pt, &pt_want);

    let noise_have: f64 = pt.std().log2();

    assert!(
        noise_have < -((k_ct - base2k) as f64),
        "noise: {noise_have}"
    );
}

#[inline(always)]
fn reverse_bits_msb(x: usize, n: u32) -> usize {
    x.reverse_bits() >> (usize::BITS - n)
}