feat(shortint): update noise level in operations

zama-ai · Oct 23, 2023 · 92cfa11 · 92cfa11
1 parent 4059dad
commit 92cfa11
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Showing 4 changed files with 10 additions and 2 deletions.
diff --git a/tfhe/src/shortint/engine/server_side/add.rs b/tfhe/src/shortint/engine/server_side/add.rs
@@ -21,6 +21,7 @@ impl ShortintEngine {
     ) -> EngineResult<()> {
         lwe_ciphertext_add_assign(&mut ct_left.ct, &ct_right.ct);
         ct_left.degree = Degree(ct_left.degree.0 + ct_right.degree.0);
+        ct_left.noise_level += ct_right.noise_level;
         Ok(())
     }
 

diff --git a/tfhe/src/shortint/engine/server_side/mod.rs b/tfhe/src/shortint/engine/server_side/mod.rs
@@ -8,7 +8,7 @@ use crate::core_crypto::commons::parameters::{
 use crate::core_crypto::entities::*;
 use crate::core_crypto::fft_impl::fft64::crypto::bootstrap::FourierLweBootstrapKey;
 use crate::core_crypto::fft_impl::fft64::math::fft::Fft;
-use crate::shortint::ciphertext::Degree;
+use crate::shortint::ciphertext::{Degree, NoiseLevel};
 use crate::shortint::engine::EngineResult;
 use crate::shortint::parameters::{MessageModulus, ShortintKeySwitchingParameters};
 use crate::shortint::server_key::{
@@ -368,6 +368,7 @@ impl ShortintEngine {
         };
 
         ct.degree = acc.degree;
+        ct.noise_level = NoiseLevel::NOMINAL;
 
         Ok(())
     }
@@ -630,6 +631,7 @@ impl ShortintEngine {
         );
 
         ct.degree = acc.degree;
+        ct.noise_level = NoiseLevel::NOMINAL;
 
         Ok(())
     }
@@ -778,6 +780,8 @@ impl ShortintEngine {
         trivially_encrypt_lwe_ciphertext(&mut ct.ct, encoded);
 
         ct.degree = Degree(modular_value);
+        ct.noise_level = NoiseLevel::ZERO;
+
         Ok(())
     }
 }
diff --git a/tfhe/src/shortint/engine/server_side/scalar_mul.rs b/tfhe/src/shortint/engine/server_side/scalar_mul.rs
@@ -1,6 +1,6 @@
 use crate::core_crypto::algorithms::*;
 use crate::core_crypto::entities::*;
-use crate::shortint::ciphertext::Degree;
+use crate::shortint::ciphertext::{Degree, NoiseLevel};
 use crate::shortint::engine::{EngineResult, ShortintEngine};
 use crate::shortint::{Ciphertext, ServerKey};
 
@@ -24,6 +24,7 @@ impl ShortintEngine {
         match scalar {
             0 => {
                 trivially_encrypt_lwe_ciphertext(&mut ct.ct, Plaintext(0));
+                ct.noise_level = NoiseLevel::ZERO;
                 ct.degree = Degree(0);
             }
             1 => {
@@ -34,6 +35,7 @@ impl ShortintEngine {
                 let cleartext_scalar = Cleartext(scalar);
                 lwe_ciphertext_cleartext_mul_assign(&mut ct.ct, cleartext_scalar);
 
+                ct.noise_level *= scalar as usize;
                 ct.degree = Degree(ct.degree.0 * scalar as usize);
             }
         }

diff --git a/tfhe/src/shortint/engine/server_side/sub.rs b/tfhe/src/shortint/engine/server_side/sub.rs
@@ -49,6 +49,7 @@ impl ShortintEngine {
 
         lwe_ciphertext_add_assign(&mut ct_left.ct, &neg_right.ct);
 
+        ct_left.noise_level += ct_right.noise_level;
         ct_left.degree = Degree(ct_left.degree.0 + z as usize);
 
         Ok(z)
-Original file line number
+Diff line change
@@ Expand Up / @@ -49,6 +49,7 @@ impl ShortintEngine { @@
             lwe_ciphertext_add_assign(&mut ct_left.ct, &neg_right.ct);
+            ct_left.noise_level += ct_right.noise_level;
             ct_left.degree = Degree(ct_left.degree.0 + z as usize);
             Ok(z)
@@ Expand Down @@