poulpy_core/layouts/prepared/
glwe.rs

1use poulpy_hal::{
2    api::{VecZnxDftAlloc, VecZnxDftApply, VecZnxDftBytesOf},
3    layouts::{Backend, Data, Module, VecZnxDft, VecZnxDftToBackendMut, VecZnxDftToBackendRef},
4};
5
6use crate::layouts::{Base2K, Degree, GLWEInfos, GLWEToBackendRef, GetDegree, LWEInfos, Rank, TorusPrecision};
7
8/// DFT-domain (prepared) variant of [`GLWE`].
9///
10/// Stores polynomials in the frequency domain of the backend's DFT/NTT
11/// transform, enabling O(N log N) polynomial multiplication.
12/// Tied to a specific backend via `B: Backend`.
13#[derive(PartialEq, Eq)]
14pub struct GLWEPrepared<D: Data, B: Backend> {
15    pub(crate) data: VecZnxDft<D, B>,
16    pub(crate) base2k: Base2K,
17}
18
19pub type GLWEPreparedBackendRef<'a, B> = GLWEPrepared<<B as Backend>::BufRef<'a>, B>;
20pub type GLWEPreparedBackendMut<'a, B> = GLWEPrepared<<B as Backend>::BufMut<'a>, B>;
21
22impl<D: Data, B: Backend> LWEInfos for GLWEPrepared<D, B> {
23    fn base2k(&self) -> Base2K {
24        self.base2k
25    }
26
27    fn size(&self) -> usize {
28        self.data.size()
29    }
30
31    fn n(&self) -> Degree {
32        Degree(self.data.n() as u32)
33    }
34}
35
36impl<D: Data, B: Backend> GLWEInfos for GLWEPrepared<D, B> {
37    fn rank(&self) -> Rank {
38        Rank(self.data.cols() as u32 - 1)
39    }
40}
41
42/// Trait for allocating and preparing DFT-domain GLWE ciphertexts.
43pub trait GLWEPreparedFactory<B: Backend>
44where
45    Self: GetDegree + VecZnxDftAlloc<B> + VecZnxDftBytesOf + VecZnxDftApply<B>,
46{
47    /// Allocates a new prepared GLWE with the given parameters.
48    fn glwe_prepared_alloc(&self, base2k: Base2K, k: TorusPrecision, rank: Rank) -> GLWEPrepared<B::OwnedBuf, B> {
49        GLWEPrepared {
50            data: self.vec_znx_dft_alloc((rank + 1).into(), k.0.div_ceil(base2k.0) as usize),
51            base2k,
52        }
53    }
54
55    fn glwe_prepared_alloc_from_infos<A>(&self, infos: &A) -> GLWEPrepared<B::OwnedBuf, B>
56    where
57        A: GLWEInfos,
58    {
59        self.glwe_prepared_alloc(infos.base2k(), infos.max_k(), infos.rank())
60    }
61
62    fn glwe_prepared_bytes_of(&self, base2k: Base2K, k: TorusPrecision, rank: Rank) -> usize {
63        self.bytes_of_vec_znx_dft((rank + 1).into(), k.0.div_ceil(base2k.0) as usize)
64    }
65
66    fn glwe_prepared_bytes_of_from_infos<A>(&self, infos: &A) -> usize
67    where
68        A: GLWEInfos,
69    {
70        self.glwe_prepared_bytes_of(infos.base2k(), infos.max_k(), infos.rank())
71    }
72
73    fn glwe_prepare<R, O>(&self, res: &mut R, other: &O)
74    where
75        R: GLWEPreparedToBackendMut<B>,
76        O: GLWEToBackendRef<B> + GLWEInfos,
77    {
78        let mut res = res.to_backend_mut();
79        let other = other.to_backend_ref();
80
81        assert_eq!(res.n(), self.ring_degree());
82        assert_eq!(other.n(), self.ring_degree());
83        assert_eq!(res.size(), other.size());
84        assert_eq!(res.max_k(), other.max_k());
85        assert_eq!(res.base2k(), other.base2k());
86
87        for i in 0..(res.rank() + 1).into() {
88            self.vec_znx_dft_apply(1, 0, &mut res.data, i, &other.data, i);
89        }
90    }
91}
92
93impl<B: Backend> GLWEPreparedFactory<B> for Module<B> where Self: VecZnxDftAlloc<B> + VecZnxDftBytesOf + VecZnxDftApply<B> {}
94
95// module-only API: allocation/size helpers are provided by `GLWEPreparedFactory` on `Module`.
96
97// module-only API: preparation is provided by `GLWEPreparedFactory` on `Module`.
98
99pub trait GLWEPreparedToBackendRef<B: Backend> {
100    fn to_backend_ref(&self) -> GLWEPreparedBackendRef<'_, B>;
101}
102
103impl<B: Backend> GLWEPreparedToBackendRef<B> for GLWEPrepared<B::OwnedBuf, B> {
104    fn to_backend_ref(&self) -> GLWEPreparedBackendRef<'_, B> {
105        GLWEPrepared {
106            data: self.data.to_backend_ref(),
107            base2k: self.base2k,
108        }
109    }
110}
111
112pub trait GLWEPreparedToBackendMut<B: Backend> {
113    fn to_backend_mut(&mut self) -> GLWEPreparedBackendMut<'_, B>;
114}
115
116impl<B: Backend> GLWEPreparedToBackendMut<B> for GLWEPrepared<B::OwnedBuf, B> {
117    fn to_backend_mut(&mut self) -> GLWEPreparedBackendMut<'_, B> {
118        GLWEPrepared {
119            data: self.data.to_backend_mut(),
120            base2k: self.base2k,
121        }
122    }
123}
poulpy_core/layouts/prepared/glwe.rs

poulpy_core/layouts/prepared/
glwe.rs
