clean rgsw/keygen

src/bool/evaluator.rs

@@ -25,8 +25,8 @@ use crate::{
         RandomFillUniformInModulus, RandomGaussianElementInModulus,
     },
     rgsw::{
-        decrypt_rlwe, galois_auto, galois_key_gen, generate_auto_map, public_key_encrypt_rgsw,
-        rgsw_by_rgsw_inplace, secret_key_encrypt_rgsw,
+        decrypt_rlwe, galois_auto, generate_auto_map, public_key_encrypt_rgsw,
+        rgsw_by_rgsw_inplace, secret_key_encrypt_rgsw, seeded_auto_key_gen,
     },
     utils::{
         encode_x_pow_si_with_emebedding_factor, fill_random_ternary_secret_with_hamming_weight,
@@ -864,7 +864,7 @@ where
                     (g.pow(i as u32) % br_q) as isize
                 };
                 let mut gk = M::zeros(self.pbs_info.auto_decomposer.decomposition_count(), rlwe_n);
-                galois_key_gen(
+                seeded_auto_key_gen(
                     &mut gk,
                     &sk_rlwe,
                     g_pow,
@@ -2010,7 +2010,7 @@ where
                     self.pbs_info.auto_decomposer.decomposition_count(),
                     ring_size,
                 );
-                galois_key_gen(
+                seeded_auto_key_gen(
                     &mut ksk_out,
                     sk_rlwe,
                     g_pow,

src/bool/ni_mp_api.rs

@@ -178,7 +178,7 @@ mod impl_enc_dec {
         bool::{evaluator::BoolEncoding, keys::NonInteractiveMultiPartyClientKey},
         pbs::{sample_extract, PbsInfo, WithShoupRepr},
         random::{NewWithSeed, RandomFillUniformInModulus},
-        rgsw::{key_switch, secret_key_encrypt_rlwe},
+        rgsw::{key_switch, seeded_secret_key_encrypt_rlwe},
         utils::TryConvertFrom1,
         Encryptor, KeySwitchWithId, Matrix, MatrixEntity, MatrixMut, RowEntity, RowMut,
     };
@@ -296,7 +296,7 @@ mod impl_enc_dec {
                             let mut rlwe_out =
                                 <<Mat as Matrix>::R as RowEntity>::zeros(parameters.rlwe_n().0);
 
-                            secret_key_encrypt_rlwe(
+                            seeded_secret_key_encrypt_rlwe(
                                 &message,
                                 &mut rlwe_out,
                                 &sk_u,

src/ntt.rs

@@ -50,7 +50,7 @@ pub fn forward_butterly_0_to_4q(
 
 pub fn forward_butterly_0_to_2q(
     mut x: u64,
-    mut y: u64,
+    y: u64,
     w: u64,
     w_shoup: u64,
     q: u64,
@@ -310,7 +310,7 @@ pub(crate) fn find_primitive_root(q: u64, n: u64, rng: &mut R) -> Op
 pub struct NttBackendU64 {
     q: u64,
     q_twice: u64,
-    n: u64,
+    _n: u64,
     n_inv: u64,
     n_inv_shoup: u64,
     psi_powers_bo: Box<[u64]>,
@@ -374,7 +374,7 @@ impl NttBackendU64 {
         NttBackendU64 {
             q,
             q_twice: 2 * q,
-            n: n as u64,
+            _n: n as u64,
             n_inv,
             n_inv_shoup: ShoupMul::representation(n_inv, q),
             psi_powers_bo: psi_powers_bo.into_boxed_slice(),
@@ -393,17 +393,6 @@ impl> NttInit for NttBackendU64 {
     }
 }
 
-impl NttBackendU64 {
-    fn reduce_from_lazy(&self, a: &mut [u64]) {
-        let q = self.q;
-        a.iter_mut().for_each(|a0| {
-            if *a0 >= q {
-                *a0 = *a0 - q;
-            }
-        });
-    }
-}
-
 impl Ntt for NttBackendU64 {
     type Element = u64;
 
@@ -458,9 +447,9 @@ mod tests {
     use rand::{thread_rng, Rng};
     use rand_distr::Uniform;
 
-    use super::{NttBackendU64, NttInit};
+    use super::NttBackendU64;
     use crate::{
-        backend::{ArithmeticOps, ModInit, ModularOpsU64, VectorOps},
+        backend::{ModInit, ModularOpsU64, VectorOps},
         ntt::Ntt,
         utils::{generate_prime, negacyclic_mul},
     };

src/rgsw/keygen.rs

@@ -1,25 +1,16 @@
-use std::{
-    clone,
-    fmt::Debug,
-    iter,
-    marker::PhantomData,
-    ops::{Div, Neg, Sub},
-};
+use std::{fmt::Debug, ops::Sub};
 
-use itertools::{izip, Itertools};
+use itertools::izip;
 use num_traits::{PrimInt, Signed, ToPrimitive, Zero};
 
 use crate::{
     backend::{ArithmeticOps, GetModulus, Modulus, VectorOps},
-    decomposer::{self, Decomposer, RlweDecomposer},
-    ntt::{self, Ntt, NttInit},
+    ntt::Ntt,
     random::{
-        DefaultSecureRng, NewWithSeed, RandomElementInModulus, RandomFill,
-        RandomFillGaussianInModulus, RandomFillUniformInModulus,
+        RandomElementInModulus, RandomFill, RandomFillGaussianInModulus, RandomFillUniformInModulus,
     },
-    rgsw::decompose_r,
-    utils::{fill_random_ternary_secret_with_hamming_weight, TryConvertFrom1, WithLocal},
-    Matrix, MatrixEntity, MatrixMut, Row, RowEntity, RowMut, Secret, ShoupMatrixFMA,
+    utils::{fill_random_ternary_secret_with_hamming_weight, TryConvertFrom1},
+    Matrix, MatrixEntity, MatrixMut, Row, RowEntity, RowMut,
 };
 
 pub(crate) fn generate_auto_map(ring_size: usize, k: isize) -> (Vec<usize>, Vec<bool>) {
@@ -49,13 +40,31 @@ pub(crate) fn generate_auto_map(ring_size: usize, k: isize) -> (Vec, Vec<
     (auto_map_index, auto_sign_index)
 }
 
-/// Encrypts message m as a RGSW ciphertext.
+/// Returns RGSW(m)
+///
+/// RGSW = [RLWE'(-sm) || RLWE(m)] = [RLWE'_A(-sm), RLWE'_B(-sm), RLWE'_A(m),
+/// RLWE'_B(m)]
+///
+/// RGSW(m1) ciphertext is used for RLWE(m0) x RGSW(m1) multiplication.
+/// Let RLWE(m) = [a, b] where b = as + e + m0.
+/// For RLWExRGSW we calculate:
+///       (\sum signed_decompose(a)[i] x RLWE(-s \beta^i' m1))
+///     + (\sum signed_decompose(b)[i'] x RLWE(\beta^i' m1))
+///     = RLWE(m0m1)
+/// We denote decomposer count for signed_decompose(a)[i] with d_a and
+/// corresponding gadget vector with `gadget_a`. We denote decomposer count for
+/// signed_decompose(b)[i] with d_b and corresponding gadget vector with
+/// `gadget_b`
 ///
-/// - m_eval: is `m` is evaluation domain
-/// - out_rgsw: RGSW(m) is stored as single matrix of dimension (d_rgsw * 3,
-///   ring_size). The matrix has the following structure [RLWE'_A(-sm) ||
-///   RLWE'_B(-sm) || RLWE'_B(m)]^T and RLWE'_A(m) is generated via seed (where
-///   p_rng is assumed to be seeded with seed)
+/// In secret key RGSW encrypton RLWE'_A(m) can be seeded. Hence, we seed it
+/// using the `p_rng` passed and the retured RGSW ciphertext has d_a * 2 + d_b
+/// rows
+///
+/// - s: is the secret key
+/// - m: message to encrypt
+/// - gadget_a: Gadget vector for RLWE'(-sm)
+/// - gadget_b: Gadget vector for RLWE'(m)
+/// - p_rng: Seeded psuedo random generator used to sample RLWE'_A(m).
 pub(crate) fn secret_key_encrypt_rgsw<
     Mmut: MatrixMut + MatrixEntity,
     S,
@@ -150,6 +159,13 @@ pub(crate) fn secret_key_encrypt_rgsw<
     });
 }
 
+/// Returns RGSW(m) encrypted with public key
+///
+/// Follows the same routine as `secret_key_encrypt_rgsw` but with the
+/// difference that each RLWE encryption uses public key instead of secret key.
+///
+/// Since public key encryption cannot be seeded `RLWE'_A(m)` is included in the
+/// ciphertext. Hence the returned RGSW ciphertext has d_a * 2 + d_b * 2 rows
 pub(crate) fn public_key_encrypt_rgsw<
     Mmut: MatrixMut + MatrixEntity,
     M: Matrix<MatElement = Mmut::MatElement>,
@@ -269,20 +285,25 @@ pub(crate) fn public_key_encrypt_rgsw<
     });
 }
 
-/// Generates RLWE Key switching key to key switch ciphertext RLWE_{from_s}(m)
+/// Returns key switching key to key switch ciphertext RLWE_{from_s}(m)
 /// to RLWE_{to_s}(m).
 ///
-/// Key switching equals
-///     \sum decompose(c_1)_i * RLWE_{to_s}(\beta^i -from_s)
-/// Hence, key switchin key equals RLWE'(-from_s) = RLWE(-from_s), RLWE(beta^1
-/// -from_s), ..., RLWE(beta^{d-1} -from_s).
+/// Let key switching decomposer have `d` decompostion count with gadget vector:
+/// [1, \beta, ..., \beta^d-1]
 ///
-/// - ksk_out: Output Key switching key. Key switching key stores only part B
-///   polynomials of ksk RLWE ciphertexts (i.e. RLWE'_B(-from_s)) in coefficient
-///   domain
-/// - neg_from_s: Negative of secret polynomial to key switch from
+/// Key switching key consists of `d` RLWE ciphertexts:
+/// RLWE'_{to_s}(-from_s) = [RLWE_{to_s}(\beta^i -from_s)]
+///
+/// In RLWE(m) s.t. b = as + e + m where s is the secret key, `a` can be seeded.
+/// And we seed all RLWE ciphertexts in key switchin key.
+///
+/// - neg_from_s: Negative of secret polynomial to key switch from (i.e.
+///   -from_s)
 /// - to_s: secret polynomial to key switch to.
-pub(crate) fn rlwe_ksk_gen<
+/// - gadget_vector: Gadget vector of decomposer used in key switch
+/// - p_rng: Seeded pseudo random generate used to generate `a` polynomials of
+///   key switching key RLWE ciphertexts
+fn seeded_rlwe_ksk_gen<
     Mmut: MatrixMut + MatrixEntity,
     ModOp: ArithmeticOps<Element = Mmut::MatElement>
         + VectorOps<Element = Mmut::MatElement>
@@ -341,7 +362,18 @@ pub(crate) fn rlwe_ksk_gen<
     });
 }
 
-pub(crate) fn galois_key_gen<
+/// Returns auto key to send RLWE(m(X)) -> RLWE(m(X^k))
+///
+/// Auto key is key switchin key that key-switches RLWE_{s(X^k)}(m(X^k)) to
+/// RLWE_{s(X)}(m(X^k)).
+///
+/// - s: secret polynomial s(X)
+/// - auto_k: k used in for autmorphism X -> X^k
+/// - gadget_vector: Gadget vector corresponding to decomposer used in key
+///   switch
+/// - p_rng: pseudo random generator used to generate `a` polynomials of key
+///   switching key RLWE ciphertexts
+pub(crate) fn seeded_auto_key_gen<
     Mmut: MatrixMut + MatrixEntity,
     ModOp: ArithmeticOps<Element = Mmut::MatElement>
         + VectorOps<Element = Mmut::MatElement>
@@ -385,7 +417,7 @@ pub(crate) fn galois_key_gen<
     );
 
     // Ksk from -s(X^k) to s(X)
-    rlwe_ksk_gen(
+    seeded_rlwe_ksk_gen(
         ksk_out,
         neg_s_auto,
         s,
@@ -397,12 +429,14 @@ pub(crate) fn galois_key_gen<
     );
 }
 
-/// Encrypt polynomial m(X) as RLWE ciphertext.
+/// Returns seeded RLWE(m(X))
+///
+/// RLWE(m(X)) = [a(X), b(X) = a(X)s(X) + e(X) + m(X)]
 ///
-/// - rlwe_out: returned RLWE ciphertext RLWE(m) in coefficient domain. RLWE
-///   ciphertext is a matirx with first row consiting polynomial `a` and the
-///   second rows consting polynomial `b`
-pub(crate) fn secret_key_encrypt_rlwe<
+/// a(X) of RLWE encyrptions using secret key s(X) can be seeded. We use seeded
+/// pseudo random generator `p_rng` to sample a(X) and return seeded RLWE
+/// ciphertext (i.e. only b(X))
+pub(crate) fn seeded_secret_key_encrypt_rlwe<
     Ro: Row + RowMut + RowEntity,
     ModOp: VectorOps<Element = Ro::Element> + GetModulus<Element = Ro::Element>,
     NttOp: Ntt<Element = Ro::Element>,
@@ -446,6 +480,9 @@ pub(crate) fn secret_key_encrypt_rlwe<
     mod_op.elwise_add_mut(b_rlwe_out.as_mut(), sa.as_ref());
 }
 
+/// Returns RLWE(m(X)) encrypted using public key.
+///
+/// Unlike secret key encryption, public key encryption cannot be seeded
 pub(crate) fn public_key_encrypt_rlwe<
     M: Matrix,
     Mmut: MatrixMut<MatElement = M::MatElement>,
@@ -507,8 +544,8 @@ pub(crate) fn public_key_encrypt_rlwe<
     mod_op.elwise_add_mut(rlwe_out.get_row_mut(1), m);
 }
 
-/// Generates RLWE public key
-pub(crate) fn gen_rlwe_public_key<
+/// Returns RLWE public key generated using RLWE secret key
+pub(crate) fn rlwe_public_key<
     Ro: RowMut + RowEntity,
     S,
     ModOp: VectorOps<Element = Ro::Element> + GetModulus<Element = Ro::Element>,
@@ -549,9 +586,9 @@ pub(crate) fn gen_rlwe_public_key<
     mod_op.elwise_add_mut(part_b_out.as_mut(), sa.as_ref());
 }
 
-/// Decrypts degree 1 RLWE ciphertext RLWE(m) and returns m
+/// Decrypts ciphertext RLWE(m) and returns noisy m
 ///
-/// - rlwe_ct: input degree 1 ciphertext RLWE(m).
+/// We assume RLWE(m) = [a, b] is a degree 1 ciphertext s.t. b - sa = e + m
 pub(crate) fn decrypt_rlwe<
     R: RowMut,
     M: Matrix<MatElement = R::Element>,

src/rgsw/mod.rs

@@ -524,8 +524,9 @@ pub(crate) mod tests {
 
     use super::{
         keygen::{
-            decrypt_rlwe, galois_key_gen, gen_rlwe_public_key, generate_auto_map, measure_noise,
-            public_key_encrypt_rgsw, secret_key_encrypt_rgsw, secret_key_encrypt_rlwe,
+            decrypt_rlwe, generate_auto_map, measure_noise, public_key_encrypt_rgsw,
+            rlwe_public_key, secret_key_encrypt_rgsw, seeded_auto_key_gen,
+            seeded_secret_key_encrypt_rlwe,
         },
         runtime::{galois_auto, rgsw_by_rgsw_inplace, rlwe_by_rgsw},
         AutoKeyEvaluationDomain, RgswCiphertext, RgswCiphertextEvaluationDomain, RlweCiphertext,
@@ -549,7 +550,7 @@ pub(crate) mod tests {
         let mut seeded_rlwe_ct =
             SeededRlweCiphertext::<_, [u8; 32], _>::empty(ring_size as usize, rlwe_seed, q.clone());
         let mut p_rng = DefaultSecureRng::new_seeded(rlwe_seed);
-        secret_key_encrypt_rlwe(
+        seeded_secret_key_encrypt_rlwe(
             &m,
             &mut seeded_rlwe_ct.data,
             s,
@@ -782,7 +783,7 @@ pub(crate) mod tests {
         let mut pk_prng = DefaultSecureRng::new_seeded(pk_seed);
         let mut seeded_pk =
             SeededRlwePublicKey::<Vec<u64>, _>::empty(ring_size as usize, pk_seed, q);
-        gen_rlwe_public_key(
+        rlwe_public_key(
             &mut seeded_pk.data,
             s.values(),
             &ntt_op,
@@ -934,7 +935,7 @@ pub(crate) mod tests {
         rng.fill_bytes(&mut seed_rlwe);
         let mut seeded_rlwe_m = SeededRlweCiphertext::empty(ring_size as usize, seed_rlwe, q);
         let mut p_rng = DefaultSecureRng::new_seeded(seed_rlwe);
-        secret_key_encrypt_rlwe(
+        seeded_secret_key_encrypt_rlwe(
             &encoded_m,
             &mut seeded_rlwe_m.data,
             s.values(),
@@ -955,7 +956,7 @@ pub(crate) mod tests {
             SeededAutoKey::empty(ring_size as usize, &decomposer, seed_auto, q);
         let mut p_rng = DefaultSecureRng::new_seeded(seed_auto);
         let gadget_vector = decomposer.gadget_vector();
-        galois_key_gen(
+        seeded_auto_key_gen(
             &mut seeded_auto_key.data,
             s.values(),
             auto_k,

src/utils.rs

@@ -1,12 +1,12 @@
-use std::{fmt::Debug, usize, vec};
+use std::{usize, vec};
 
 use itertools::{izip, Itertools};
-use num_traits::{FromPrimitive, One, PrimInt, Signed};
+use num_traits::{One, PrimInt, Signed};
 
 use crate::{
     backend::Modulus,
     random::{RandomElementInModulus, RandomFill},
-    Matrix, Row, RowEntity, RowMut,
+    Matrix, RowEntity, RowMut,
 };
 pub trait WithLocal {
     fn with_local<F, R>(func: F) -> R
@@ -163,11 +163,11 @@ pub fn mod_exponent(a: u64, mut b: u64, q: u64) -> u64 {
     out
 }
 
-pub fn mod_inverse(a: u64, q: u64) -> u64 {
+pub(crate) fn mod_inverse(a: u64, q: u64) -> u64 {
     mod_exponent(a, q - 2, q)
 }
 
-pub fn negacyclic_mul<T: PrimInt, F: Fn(&T, &T) -> T>(
+pub(crate) fn negacyclic_mul<T: PrimInt, F: Fn(&T, &T) -> T>(
     a: &[T],
     b: &[T],
     mul: F,