Improve GGSW-based blind rotation API

CHANGELOG.md

@@ -2,13 +2,18 @@
 
 ## [0.3.2] - 2025-10-27
 
+### `poulpy-schemes`
+ - Added `sign` argument to GGSW-based blind rotation, which enables to choose the rotation direction of the test vector.
+
+## [0.3.2] - 2025-10-27
+
 ### `poulpy-hal`
 - Improved convolution functionality
 
 ### `poulpy-core`
  - Rename `GLWEToLWESwitchingKey` to `GLWEToLWEKey`.
  - Rename `LWEToGLWESwitchingKey` to `LWEToGLWEKey`.
- - Add `GLWESecretTensor` which stores the flattened upper triangular matrix of the pairs  `sk[i] * sk[j]`.
+ - Add `GLWESecretTensor` which stores the flattened upper right of the tensor matrix of the pairs  `sk[i] * sk[j]`.
  - Add `GGLWEToGGSWKey`, `GGLWEToGGSWKeyPrepared`, `GGLWEToGGSWKeyCompressed`, which encrypts the full tensor matrix of all pairs `sk[i] * sk[j]`, with one `GGLWE` per row.
  - Update `GGLWEToGGSW` API to take `GGLWEToGGSWKey` instead of the `GLWETensorKey`
  - Add `GLWETensor`, the result of tensoring two `GLWE` of identical rank.

Cargo.lock

@@ -401,7 +401,7 @@ dependencies = [
 
 [[package]]
 name = "poulpy-schemes"
-version = "0.3.2"
+version = "0.3.3"
 dependencies = [
  "byteorder",
  "criterion",

poulpy-schemes/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "poulpy-schemes"
-version = "0.3.2"
+version = "0.3.3"
 edition = "2024"
 license = "Apache-2.0"
 readme = "README.md"

poulpy-schemes/src/tfhe/bdd_arithmetic/blind_rotation.rs

@@ -36,7 +36,8 @@ where
         res: &mut R,
         a: &A,
         k: &K,
-        bit_start: usize,
+        sign: bool,
+        bit_rsh: usize,
         bit_mask: usize,
         bit_lsh: usize,
         scratch: &mut Scratch<BE>,
@@ -58,7 +59,8 @@ where
                     &mut res.at_mut(row, col),
                     &a.at(row, col),
                     k,
-                    bit_start,
+                    sign,
+                    bit_rsh,
                     bit_mask,
                     bit_lsh,
                     scratch,
@@ -81,7 +83,8 @@ where
         res: &mut R,
         test_vector: &S,
         k: &K,
-        bit_start: usize,
+        sign: bool,
+        bit_rsh: usize,
         bit_mask: usize,
         bit_lsh: usize,
         scratch: &mut Scratch<BE>,
@@ -115,7 +118,8 @@ where
                     &mut res.at_mut(row, col),
                     &tmp_glwe,
                     k,
-                    bit_start,
+                    sign,
+                    bit_rsh,
                     bit_mask,
                     bit_lsh,
                     scratch_1,
@@ -146,12 +150,13 @@ where
     }
 
     #[allow(clippy::too_many_arguments)]
-    /// res <- a * X^{((k>>bit_rsh) % 2^bit_mask) << bit_lsh}.
+    /// res <- a * X^{sign * ((k>>bit_rsh) % 2^bit_mask) << bit_lsh}.
     fn glwe_to_glwe_blind_rotation<R, A, K>(
         &self,
         res: &mut R,
         a: &A,
         k: &K,
+        sign: bool,
         bit_rsh: usize,
         bit_mask: usize,
         bit_lsh: usize,
@@ -170,7 +175,10 @@ where
         let (mut tmp_res, scratch_1) = scratch.take_glwe(&res);
 
         // a <- a ; b <- a * X^{-2^{i + bit_lsh}}
-        self.glwe_rotate(-1 << bit_lsh, &mut res, a);
+        match sign {
+            true => self.glwe_rotate(1 << bit_lsh, &mut res, a),
+            false => self.glwe_rotate(-1 << bit_lsh, &mut res, a),
+        }
 
         // b <- (b - a) * GGSW(b[i]) + a
         self.cmux_inplace(&mut res, a, &k.get_bit(bit_rsh), scratch_1);
@@ -187,7 +195,10 @@ where
             };
 
             // a <- a ; b <- a * X^{-2^{i + bit_lsh}}
-            self.glwe_rotate(-1 << (i + bit_lsh), b, a);
+            match sign {
+                true => self.glwe_rotate(1 << (i + bit_lsh), b, a),
+                false => self.glwe_rotate(-1 << (i + bit_lsh), b, a),
+            }
 
             // b <- (b - a) * GGSW(b[i]) + a
             self.cmux_inplace(b, a, &k.get_bit(i + bit_rsh), scratch_1);

poulpy-schemes/src/tfhe/bdd_arithmetic/tests/test_suite/ggsw_blind_rotations.rs

@@ -121,6 +121,7 @@ where
                 &mut res,
                 &scalar,
                 &k_enc_prep,
+                false,
                 bit_start,
                 bit_size,
                 bit_step,

poulpy-schemes/src/tfhe/bdd_arithmetic/tests/test_suite/glwe_blind_rotation.rs

@@ -106,6 +106,7 @@ where
                 &mut res,
                 &test_glwe,
                 &k_enc_prep,
+                false,
                 bit_start,
                 bit_size,
                 bit_step,