chore!: use u64 for NoiseLevel

Change from usize to u64 for MaxNoiseLevel and NoiseLevel

This is an API break as `new` and `get` handle/returns u64
instead of usize

This is also a potential serialization break depending on the
serializer used (bincode should be fine as it serializes usize as u64)

Author: tmontaigu

tfhe/src/c_api/shortint/parameters.rs

@@ -62,7 +62,7 @@ impl TryFrom<ShortintPBSParameters> for crate::shortint::ClassicPBSParameters {
                 c_params.modulus_power_of_2_exponent,
             )?,
             max_noise_level: crate::shortint::parameters::MaxNoiseLevel::new(
-                c_params.max_noise_level,
+                c_params.max_noise_level as u64,
             ),
             log2_p_fail: c_params.log2_p_fail,
             encryption_key_choice: c_params.encryption_key_choice.into(),
@@ -113,7 +113,7 @@ impl ShortintPBSParameters {
             ks_level: rust_params.ks_level.0,
             message_modulus: rust_params.message_modulus.0,
             carry_modulus: rust_params.carry_modulus.0,
-            max_noise_level: rust_params.max_noise_level.get(),
+            max_noise_level: rust_params.max_noise_level.get() as usize,
             log2_p_fail: rust_params.log2_p_fail,
             modulus_power_of_2_exponent: convert_modulus(rust_params.ciphertext_modulus),
             encryption_key_choice: ShortintEncryptionKeyChoice::convert(

tfhe/src/integer/server_key/mod.rs

@@ -246,7 +246,7 @@ impl ServerKey {
             MaxDegree::from_msg_carry_modulus(self.message_modulus(), self.carry_modulus());
         let max_sum_to_full_carry = max_degree.get() / degree.get();
 
-        max_sum_to_full_carry.min(self.key.max_noise_level.get())
+        max_sum_to_full_carry.min(self.key.max_noise_level.get() as usize)
     }
 }
 

tfhe/src/integer/server_key/radix_parallel/add.rs

@@ -854,7 +854,8 @@ impl ServerKey {
 
         // Just in case we compare with max noise level, but it should always be num_bits_in_blocks
         // with the parameters we provide
-        let grouping_size = (num_bits_in_block as usize).min(self.key.max_noise_level.get());
+        let grouping_size =
+            (num_bits_in_block as usize).min(self.key.max_noise_level.get() as usize);
 
         let mut output_flag = None;
 

tfhe/src/integer/server_key/radix_parallel/block_shift.rs

@@ -67,7 +67,7 @@ impl ServerKey {
         assert!(
             self.key
                 .max_noise_level
-                .validate(NoiseLevel::NOMINAL * 3usize)
+                .validate(NoiseLevel::NOMINAL * 3u64)
                 .is_ok(),
             "Parameters must support 2 additions before a PBS"
         );

tfhe/src/integer/server_key/radix_parallel/modulus_switch_compression.rs

@@ -66,7 +66,7 @@ impl ServerKey {
             "Compression does not support message_modulus > carry_modulus"
         );
         assert!(
-            self.key.max_noise_level.get() >= self.message_modulus().0 + 1,
+            self.key.max_noise_level.get() >= self.message_modulus().0 as u64 + 1,
             "Compression does not support max_noise_level < message_modulus + 1"
         );
 

tfhe/src/integer/server_key/radix_parallel/scalar_add.rs

@@ -555,7 +555,8 @@ impl ServerKey {
         let num_bits_in_block = packed_modulus.ilog2();
         // Just in case we compare with max noise level, but it should always be num_bits_in_blocks
         // with the parameters we provide
-        let grouping_size = (num_bits_in_block as usize).min(self.key.max_noise_level.get());
+        let grouping_size =
+            (num_bits_in_block as usize).min(self.key.max_noise_level.get() as usize);
 
         // In this, we store lookup tables to be used on each 'packing'.
         // These LUTs will generate an output that tells whether the packing

tfhe/src/integer/server_key/radix_parallel/scalar_sub.rs

@@ -394,7 +394,8 @@ impl ServerKey {
         let num_bits_in_block = packed_modulus.ilog2();
         // Just in case we compare with max noise level, but it should always be num_bits_in_blocks
         // with the parameters we provide
-        let grouping_size = (num_bits_in_block as usize).min(self.key.max_noise_level.get());
+        let grouping_size =
+            (num_bits_in_block as usize).min(self.key.max_noise_level.get() as usize);
 
         // In this, we store lookup tables to be used on each 'packing'.
         // These LUTs will generate an output that tells whether the packing

tfhe/src/integer/server_key/radix_parallel/sub.rs

@@ -386,7 +386,8 @@ impl ServerKey {
 
         // Just in case we compare with max noise level, but it should always be num_bits_in_blocks
         // with the parameters we provide
-        let grouping_size = (num_bits_in_block as usize).min(self.key.max_noise_level.get());
+        let grouping_size =
+            (num_bits_in_block as usize).min(self.key.max_noise_level.get() as usize);
 
         // Second step
         let (mut prepared_blocks, resolved_borrows) = {

tfhe/src/js_on_wasm_api/shortint.rs

@@ -417,7 +417,7 @@ impl Shortint {
         ks_level: usize,
         message_modulus: usize,
         carry_modulus: usize,
-        max_noise_level: usize,
+        max_noise_level: u64,
         log2_p_fail: f64,
         modulus_power_of_2_exponent: usize,
         encryption_key_choice: ShortintEncryptionKeyChoice,

tfhe/src/shortint/ciphertext/common.rs

@@ -23,16 +23,16 @@ impl std::error::Error for NotTrivialCiphertextError {}
 /// that guarantees the target p-error when doing a PBS on it
 #[derive(Debug, PartialEq, Eq, Copy, Clone, Serialize, Deserialize, Versionize)]
 #[versionize(MaxNoiseLevelVersions)]
-pub struct MaxNoiseLevel(usize);
+pub struct MaxNoiseLevel(u64);
 
 impl MaxNoiseLevel {
-    pub(crate) const UNKNOWN: Self = Self(usize::MAX);
+    pub(crate) const UNKNOWN: Self = Self(u64::MAX);
 
-    pub const fn new(value: usize) -> Self {
+    pub const fn new(value: u64) -> Self {
         Self(value)
     }
 
-    pub const fn get(&self) -> usize {
+    pub const fn get(&self) -> u64 {
         self.0
     }
 
@@ -45,7 +45,8 @@ impl MaxNoiseLevel {
         msg_modulus: MessageModulus,
         carry_modulus: CarryModulus,
     ) -> Self {
-        Self((carry_modulus.0 * msg_modulus.0 - 1) / (msg_modulus.0 - 1))
+        let level = (carry_modulus.0 * msg_modulus.0 - 1) / (msg_modulus.0 - 1);
+        Self(level as u64)
     }
 
     pub const fn validate(&self, noise_level: NoiseLevel) -> Result<(), CheckError> {
@@ -64,17 +65,17 @@ impl MaxNoiseLevel {
     Debug, PartialEq, Eq, PartialOrd, Ord, Copy, Clone, Serialize, Deserialize, Versionize,
 )]
 #[versionize(NoiseLevelVersions)]
-pub struct NoiseLevel(usize);
+pub struct NoiseLevel(u64);
 
 impl NoiseLevel {
     pub const NOMINAL: Self = Self(1);
     pub const ZERO: Self = Self(0);
     // As a safety measure the unknown noise level is set to the max value
-    pub const UNKNOWN: Self = Self(usize::MAX);
+    pub const UNKNOWN: Self = Self(u64::MAX);
 }
 
 impl NoiseLevel {
-    pub fn get(&self) -> usize {
+    pub fn get(&self) -> u64 {
         self.0
     }
 }
@@ -94,16 +95,16 @@ impl std::ops::Add for NoiseLevel {
     }
 }
 
-impl std::ops::MulAssign<usize> for NoiseLevel {
-    fn mul_assign(&mut self, rhs: usize) {
+impl std::ops::MulAssign<u64> for NoiseLevel {
+    fn mul_assign(&mut self, rhs: u64) {
         self.0 = self.0.saturating_mul(rhs);
     }
 }
 
-impl std::ops::Mul<usize> for NoiseLevel {
+impl std::ops::Mul<u64> for NoiseLevel {
     type Output = Self;
 
-    fn mul(mut self, rhs: usize) -> Self::Output {
+    fn mul(mut self, rhs: u64) -> Self::Output {
         self *= rhs;
 
         self
@@ -272,14 +273,14 @@ mod tests {
 
         let mut rng = thread_rng();
 
-        assert_eq!(NoiseLevel::UNKNOWN.0, usize::MAX);
+        assert_eq!(NoiseLevel::UNKNOWN.0, u64::MAX);
 
         let max_noise_level = NoiseLevel::UNKNOWN;
-        let random_addend = rng.gen::<usize>();
+        let random_addend = rng.gen::<u64>();
         let add = max_noise_level + NoiseLevel(random_addend);
         assert_eq!(add, NoiseLevel::UNKNOWN);
 
-        let random_positive_multiplier = rng.gen_range(1usize..=usize::MAX);
+        let random_positive_multiplier = rng.gen_range(1u64..=u64::MAX);
         let mul = max_noise_level * random_positive_multiplier;
         assert_eq!(mul, NoiseLevel::UNKNOWN);
     }

tfhe/src/shortint/list_compression/compression.rs

@@ -88,7 +88,7 @@ impl CompressionKey {
 
                     let mut ct = ct.clone();
                     let max_noise_level =
-                        MaxNoiseLevel::new((ct.noise_level() * message_modulus.0).get());
+                        MaxNoiseLevel::new((ct.noise_level() * message_modulus.0 as u64).get());
                     unchecked_scalar_mul_assign(&mut ct, message_modulus.0 as u8, max_noise_level);
 
                     list.extend(ct.ct.as_ref());

tfhe/src/shortint/server_key/bivariate_pbs.rs

@@ -36,7 +36,7 @@ fn ciphertexts_can_be_packed_without_exceeding_space_or_noise(
 
     max_degree.validate(final_degree)?;
 
-    let final_noise_level = (lhs.noise_level * factor) + rhs.noise_level;
+    let final_noise_level = (lhs.noise_level * factor as u64) + rhs.noise_level;
 
     server_key.max_noise_level.validate(final_noise_level)?;
 
@@ -513,7 +513,7 @@ impl ScalingOperation {
 impl Ciphertext {
     fn noise_degree_if_scaled(&self, scale: u8) -> CiphertextNoiseDegree {
         CiphertextNoiseDegree {
-            noise_level: self.noise_level() * scale as usize,
+            noise_level: self.noise_level() * u64::from(scale),
             degree: self.degree * scale as usize,
         }
     }
@@ -524,7 +524,7 @@ impl Ciphertext {
         } = self.noise_degree_if_bootstrapped();
 
         CiphertextNoiseDegree {
-            noise_level: noise * scale as usize,
+            noise_level: noise * u64::from(scale),
             degree: degree * scale as usize,
         }
     }

tfhe/src/shortint/server_key/scalar_mul.rs

@@ -298,7 +298,7 @@ impl ServerKey {
         self.max_degree.validate(Degree::new(final_degree))?;
 
         self.max_noise_level
-            .validate(ct.noise_level * scalar as usize)?;
+            .validate(ct.noise_level * u64::from(scalar))?;
 
         Ok(())
     }
@@ -521,7 +521,7 @@ pub(crate) fn unchecked_scalar_mul_assign(
     scalar: u8,
     max_noise_level: MaxNoiseLevel,
 ) {
-    ct.set_noise_level(ct.noise_level() * scalar as usize, max_noise_level);
+    ct.set_noise_level(ct.noise_level() * u64::from(scalar), max_noise_level);
     ct.degree = Degree::new(ct.degree.get() * scalar as usize);
 
     match scalar {

tfhe/src/shortint/server_key/tests/noise_level.rs

@@ -234,7 +234,7 @@ fn test_ct_scalar_op_noise_level_propagation(sk: &ServerKey, ct: &Ciphertext, sc
     test_fn(&ServerKey::unchecked_scalar_add, &|ct_noise, _| ct_noise);
     test_fn(&ServerKey::unchecked_scalar_sub, &|ct_noise, _| ct_noise);
     test_fn(&ServerKey::unchecked_scalar_mul, &|ct_noise, scalar| {
-        ct_noise * scalar as usize
+        ct_noise * u64::from(scalar)
     });
     let expected_pbs_noise = if ct.is_trivial() {
         NoiseLevel::ZERO
@@ -281,7 +281,7 @@ fn test_ct_scalar_op_assign_noise_level_propagation(sk: &ServerKey, ct: &Ciphert
     });
     test_fn(
         &ServerKey::unchecked_scalar_mul_assign,
-        &|ct_noise, scalar| ct_noise * scalar as usize,
+        &|ct_noise, scalar| ct_noise * u64::from(scalar),
     );
     let expected_pbs_noise = if ct.is_trivial() {
         NoiseLevel::ZERO

tfhe/tests/backward_compatibility/shortint.rs

@@ -36,7 +36,7 @@ pub fn load_params(test_params: &TestParameterSet) -> ClassicPBSParameters {
         ks_level: DecompositionLevelCount(test_params.ks_level),
         message_modulus: MessageModulus(test_params.message_modulus),
         carry_modulus: CarryModulus(test_params.carry_modulus),
-        max_noise_level: MaxNoiseLevel::new(test_params.max_noise_level),
+        max_noise_level: MaxNoiseLevel::new(test_params.max_noise_level as u64),
         log2_p_fail: test_params.log2_p_fail,
         ciphertext_modulus: CiphertextModulus::try_new(test_params.ciphertext_modulus).unwrap(),
         encryption_key_choice: {