add ckks encoding and decoding

src/core_crypto/num/mod.rs

@@ -1,7 +1,9 @@
-use num_complex::Complex;
+use num_bigint::{BigInt, BigUint};
+use num_complex::{Complex, ComplexFloat};
 use num_traits::{
-    AsPrimitive, CheckedShl, CheckedShr, MulAddAssign, Num, NumAssign, NumOps, One, Pow, PrimInt,
-    ToPrimitive, WrappingAdd, WrappingMul, WrappingShl, WrappingShr, WrappingSub, Zero,
+    AsPrimitive, CheckedShl, CheckedShr, Float, MulAddAssign, Num, NumAssign, NumCast, NumOps,
+    NumRef, One, Pow, PrimInt, RefNum, ToPrimitive, WrappingAdd, WrappingMul, WrappingShl,
+    WrappingShr, WrappingSub, Zero,
 };
 use std::{
     fmt::{Debug, Display},
@@ -49,35 +51,69 @@ impl NumericConstants for u128 {
 impl UnsignedInteger for u64 {}
 impl UnsignedInteger for u128 {}
 
-pub trait Float: num_traits::Float + From<u32> {
-    const PI: Self;
-}
-
-impl Float for f64 {
-    const PI: Self = std::f64::consts::PI * 2.0;
-}
-
-pub trait ComplexNumber<T>: Num + Div<T, Output = Self>
+// TODO(Jay): How to add trait bound for impl Add<&T, Output = T> for {}. Doing
+// this remove unecessary copy bounds in ckks/ops.rs
+pub trait ComplexNumber<T>:
+    Num + NumRef + for<'r> Div<&'r T, Output = Self> + for<'r> Mul<&'r T, Output = Self>
 where
-    T: Float,
+    T: BFloat,
 {
+    fn new(re: T, im: T) -> Self;
     fn nth_root(n: u32) -> Self;
     fn powu(&self, exp: u32) -> Self;
     fn re(&self) -> T;
     fn img(&self) -> T;
 }
 
-impl<T: Debug + Float + Clone> ComplexNumber<T> for Complex<T> {
+pub trait BUint: Num + NumRef + PartialOrd {}
+
+pub trait BInt: Num + NumRef + PartialOrd {}
+
+pub trait BFloat: Num + NumRef + Float + NumCast {
+    const TWICE_PI: Self;
+}
+
+// TODO(Jay): CastToZp<To> is unecessary since it is only used on simd_encode
+// where it can easily be replaced with TryConvertFrom<[f64]> to M
+pub trait CastToZp<To> {
+    fn cast(&self, q: &To) -> To;
+}
+
+pub trait ModInverse {
+    fn mod_inverse(&self, q: Self) -> Self;
+}
+
+impl<T: BFloat + Clone> ComplexNumber<T> for Complex<T> {
+    fn new(re: T, im: T) -> Self {
+        Complex::new(re, im)
+    }
     fn nth_root(n: u32) -> Self {
-        Complex::<T>::from_polar(T::one(), T::PI / <T as From<u32>>::from(n))
+        Complex::<T>::from_polar(T::one(), T::TWICE_PI / T::from(n).unwrap())
     }
     fn powu(&self, exp: u32) -> Self {
         self.powu(exp)
     }
     fn re(&self) -> T {
-        self.re
+        self.re.clone()
     }
     fn img(&self) -> T {
-        self.im
+        self.im.clone()
+    }
+}
+
+impl BFloat for f64 {
+    const TWICE_PI: Self = std::f64::consts::PI * 2.0;
+}
+
+impl BUint for BigUint {}
+
+impl CastToZp<BigUint> for f64 {
+    fn cast(&self, q: &BigUint) -> BigUint {
+        let v = self.round();
+        if v < 0.0 {
+            q - (v.abs().to_u64().unwrap() % q)
+        } else {
+            v.to_u64().unwrap() % q
+        }
     }
 }

src/parameters.rs

@@ -9,7 +9,7 @@ use crate::{
             MontgomeryBackend, MontgomeryScalar,
         },
         ntt::{Ntt, NttConfig},
-        num::UnsignedInteger,
+        num::{BFloat, ComplexNumber, UnsignedInteger},
     },
     utils::{mod_inverse, mod_inverse_big_unit},
 };
@@ -140,3 +140,17 @@ pub trait BfvEncodingDecodingParameters: Parameters {
     fn t_ntt_op(&self) -> &Self::NttOp;
     fn modt_op(&self) -> &Self::ModOp;
 }
+
+// CKKS encoding decoding parameters
+pub trait CkksEncodingDecodingParameters: Parameters {
+    type F: BFloat;
+    type Complex: ComplexNumber<Self::F>;
+    type BU;
+
+    fn delta(&self) -> Self::F;
+    fn psi_powers(&self) -> &[Self::Complex];
+    fn rot_group(&self) -> &[usize];
+    fn ring_size(&self) -> usize;
+    fn bigq_at_level(&self, level: usize) -> &Self::BU;
+    fn q_moduli_chain_at_level(&self, level: usize) -> &[Self::Scalar];
+}