1use std::{fmt::Debug, usize, vec};
  2
  3use itertools::{izip, Itertools};
  4use num_traits::{FromPrimitive, PrimInt, Signed, Unsigned};
  5
  6use crate::{
  7    backend::Modulus,
  8    random::{RandomElement, RandomElementInModulus, RandomFill},
  9    Matrix,
 10};
 11pub trait WithLocal {
 12    fn with_local<F, R>(func: F) -> R
 13    where
 14        F: Fn(&Self) -> R;
 15
 16    fn with_local_mut<F, R>(func: F) -> R
 17    where
 18        F: Fn(&mut Self) -> R;
 19
 20    fn with_local_mut_mut<F, R>(func: &mut F) -> R
 21    where
 22        F: FnMut(&mut Self) -> R;
 23}
 24
 25pub trait Global {
 26    fn global() -> &'static Self;
 27}
 28
 29pub(crate) trait ShoupMul {
 30    fn representation(value: Self, q: Self) -> Self;
 31    fn mul(a: Self, b: Self, b_shoup: Self, q: Self) -> Self;
 32}
 33
 34impl ShoupMul for u64 {
 35    #[inline]
 36    fn representation(value: Self, q: Self) -> Self {
 37        ((value as u128 * (1u128 << 64)) / q as u128) as u64
 38    }
 39
 40    #[inline]
 41    /// Returns a * b % q
 42    fn mul(a: Self, b: Self, b_shoup: Self, q: Self) -> Self {
 43        (b.wrapping_mul(a))
 44            .wrapping_sub(q.wrapping_mul(((b_shoup as u128 * a as u128) >> 64) as u64))
 45    }
 46}
 47
 48pub(crate) trait ToShoup {
 49    type Modulus;
 50    fn to_shoup(value: &Self, modulus: Self::Modulus) -> Self;
 51}
 52
 53impl ToShoup for u64 {
 54    type Modulus = u64;
 55    fn to_shoup(value: &Self, modulus: Self) -> Self {
 56        ((*value as u128 * (1u128 << 64)) / modulus as u128) as u64
 57    }
 58}
 59
 60impl ToShoup for Vec<Vec<u64>> {
 61    type Modulus = u64;
 62    fn to_shoup(value: &Self, modulus: Self::Modulus) -> Self {
 63        let (row, col) = value.dimension();
 64        let mut shoup_value = vec![vec![0u64; col]; row];
 65        izip!(shoup_value.iter_mut(), value.iter()).for_each(|(shoup_r, r)| {
 66            izip!(shoup_r.iter_mut(), r.iter()).for_each(|(s, e)| {
 67                *s = u64::to_shoup(e, modulus);
 68            })
 69        });
 70        shoup_value
 71    }
 72}
 73
 74pub fn fill_random_ternary_secret_with_hamming_weight<
 75    T: Signed,
 76    R: RandomFill<[u8]> + RandomElementInModulus<usize, usize>,
 77>(
 78    out: &mut [T],
 79    hamming_weight: usize,
 80    rng: &mut R,
 81) {
 82    let mut bytes = vec![0u8; hamming_weight.div_ceil(8)];
 83    RandomFill::<[u8]>::random_fill(rng, &mut bytes);
 84
 85    let size = out.len();
 86    let mut secret_indices = (0..size).into_iter().map(|i| i).collect_vec();
 87    let mut bit_index = 0;
 88    let mut byte_index = 0;
 89    for _ in 0..hamming_weight {
 90        let s_index = RandomElementInModulus::<usize, usize>::random(rng, &secret_indices.len());
 91
 92        let curr_bit = (bytes[byte_index] >> bit_index) & 1;
 93        if curr_bit == 1 {
 94            out[secret_indices[s_index]] = T::one();
 95        } else {
 96            out[secret_indices[s_index]] = -T::one();
 97        }
 98
 99        secret_indices[s_index] = *secret_indices.last().unwrap();
100        secret_indices.truncate(secret_indices.len());
101
102        if bit_index == 7 {
103            bit_index = 0;
104            byte_index += 1;
105        } else {
106            bit_index += 1;
107        }
108    }
109}
110
111// TODO (Jay): this is only a workaround. Add a propoer way to perform primality
112// tests.
113fn is_probably_prime(candidate: u64) -> bool {
114    num_bigint_dig::prime::probably_prime(&num_bigint_dig::BigUint::from(candidate), 0)
115}
116
117/// Finds prime that satisfy
118/// - $prime \lt upper_bound$
119/// - $\log{prime} = num_bits$
120/// - `prime % modulo == 1`
121pub fn generate_prime(num_bits: usize, modulo: u64, upper_bound: u64) -> Option<u64> {
122    let leading_zeros = (64 - num_bits) as u32;
123
124    let mut tentative_prime = upper_bound - 1;
125    while tentative_prime % modulo != 1 && tentative_prime.leading_zeros() == leading_zeros {
126        tentative_prime -= 1;
127    }
128
129    while !is_probably_prime(tentative_prime)
130        && tentative_prime.leading_zeros() == leading_zeros
131        && tentative_prime >= modulo
132    {
133        tentative_prime -= modulo;
134    }
135
136    if is_probably_prime(tentative_prime) && tentative_prime.leading_zeros() == leading_zeros {
137        Some(tentative_prime)
138    } else {
139        None
140    }
141}
142
143/// Returns a^b mod q
144pub fn mod_exponent(a: u64, mut b: u64, q: u64) -> u64 {
145    let mod_mul = |v1: &u64, v2: &u64| {
146        let tmp = *v1 as u128 * *v2 as u128;
147        (tmp % q as u128) as u64
148    };
149
150    let mut acc = a;
151    let mut out = 1;
152    while b != 0 {
153        let flag = b & 1;
154
155        if flag == 1 {
156            out = mod_mul(&acc, &out);
157        }
158        acc = mod_mul(&acc, &acc);
159
160        b >>= 1;
161    }
162
163    out
164}
165
166pub fn mod_inverse(a: u64, q: u64) -> u64 {
167    mod_exponent(a, q - 2, q)
168}
169
170pub fn negacyclic_mul<T: PrimInt, F: Fn(&T, &T) -> T>(
171    a: &[T],
172    b: &[T],
173    mul: F,
174    modulus: T,
175) -> Vec<T> {
176    let mut r = vec![T::zero(); a.len()];
177    for i in 0..a.len() {
178        for j in 0..i + 1 {
179            // println!("i: {j} {}", i - j);
180            r[i] = (r[i] + mul(&a[j], &b[i - j])) % modulus;
181        }
182
183        for j in i + 1..a.len() {
184            // println!("i: {j} {}", a.len() - j + i);
185            r[i] = (r[i] + modulus - mul(&a[j], &b[a.len() - j + i])) % modulus;
186        }
187        // println!("")
188    }
189
190    return r;
191}
192
193pub trait TryConvertFrom1<T: ?Sized, P> {
194    fn try_convert_from(value: &T, parameters: &P) -> Self;
195}
196
197impl<P: Modulus<Element = u64>> TryConvertFrom1<[i64], P> for Vec<u64> {
198    fn try_convert_from(value: &[i64], parameters: &P) -> Self {
199        value
200            .iter()
201            .map(|v| parameters.map_element_from_i64(*v))
202            .collect_vec()
203    }
204}
205
206impl<P: Modulus<Element = u64>> TryConvertFrom1<[i32], P> for Vec<u64> {
207    fn try_convert_from(value: &[i32], parameters: &P) -> Self {
208        value
209            .iter()
210            .map(|v| parameters.map_element_from_i64(*v as i64))
211            .collect_vec()
212    }
213}
214
215impl<P: Modulus> TryConvertFrom1<[P::Element], P> for Vec<i64> {
216    fn try_convert_from(value: &[P::Element], parameters: &P) -> Self {
217        value
218            .iter()
219            .map(|v| parameters.map_element_to_i64(v))
220            .collect_vec()
221    }
222}
223
224pub(crate) struct Stats<T> {
225    pub(crate) samples: Vec<T>,
226}
227
228impl<T: PrimInt + FromPrimitive + Debug> Stats<T>
229where
230    // T: for<'a> Sum<&'a T>,
231    T: for<'a> std::iter::Sum<&'a T> + std::iter::Sum<T>,
232{
233    pub(crate) fn new() -> Self {
234        Self { samples: vec![] }
235    }
236
237    pub(crate) fn mean(&self) -> f64 {
238        self.samples.iter().sum::<T>().to_f64().unwrap() / (self.samples.len() as f64)
239    }
240
241    pub(crate) fn std_dev(&self) -> f64 {
242        let mean = self.mean();
243
244        // diff
245        let diff_sq = self
246            .samples
247            .iter()
248            .map(|v| {
249                let t = v.to_f64().unwrap() - mean;
250                t * t
251            })
252            .into_iter()
253            .sum::<f64>();
254
255        (diff_sq / (self.samples.len() as f64)).sqrt()
256    }
257
258    pub(crate) fn add_more(&mut self, values: &[T]) {
259        self.samples.extend(values.iter());
260    }
261}
262
263#[cfg(test)]
264mod tests {
265
266    // #[test]
267    // fn gg() {
268    //     let n = 1 << (11 + 1);
269    //     let mut start = 1 << 55;
270    //     while start < (1 << 56) {
271    //         if start % n == 1 {
272    //             break;
273    //         }
274    //         start += 1;
275    //     }
276
277    //     let mut prime = None;
278    //     while start < (1 << 56) {
279    //         if is_probably_prime(start) {
280    //             dbg!(start);
281    //             prime = Some(start);
282    //             break;
283    //         }
284    //         dbg!(start);
285    //         start += (n);
286    //     }
287
288    //     println!("{:?}", prime);
289    // }
290}