Remove q_sinsemilla4_private

halo2_gadgets/src/sinsemilla/chip.rs

@@ -43,11 +43,8 @@ where
     /// q_sinsemilla2 is used to define a synthetic selector,
     ///         q_sinsemilla3 = (q_sinsemilla2) ⋅ (q_sinsemilla2 - 1)
     /// Simple selector used to constrain hash initialization to be consistent with
-    /// the y-coordinate of the domain $Q$ when $y_Q$ is a public constant.
+    /// the y-coordinate of the domain $Q$.
     q_sinsemilla4: Selector,
-    /// Simple selector used to constrain hash initialization to be consistent with
-    /// the y-coordinate of the domain $Q$ when $y_Q$ is a private value.
-    q_sinsemilla4_private: Selector,
     /// Fixed column used to load the y-coordinate of the domain $Q$.
     fixed_y_q: Column<Fixed>,
     /// Logic specific to merged double-and-add.
@@ -168,7 +165,6 @@ where
             q_sinsemilla1: meta.complex_selector(),
             q_sinsemilla2: meta.fixed_column(),
             q_sinsemilla4: meta.selector(),
-            q_sinsemilla4_private: meta.selector(),
             fixed_y_q,
             double_and_add: DoubleAndAdd {
                 x_a: advices[0],
@@ -206,23 +202,8 @@ where
 
         // Check that the initial x_A, x_P, lambda_1, lambda_2 are consistent with y_Q.
         // https://p.z.cash/halo2-0.1:sinsemilla-constraints?partial
-        meta.create_gate("Initial y_Q (public)", |meta| {
+        meta.create_gate("Initial y_Q", |meta| {
             let q_s4 = meta.query_selector(config.q_sinsemilla4);
-            let y_q = meta.query_fixed(config.fixed_y_q);
-
-            // Y_A = (lambda_1 + lambda_2) * (x_a - x_r)
-            let Y_A_cur = Y_A(meta, Rotation::cur());
-
-            // 2 * y_q - Y_{A,0} = 0
-            let init_y_q_check = y_q * two - Y_A_cur;
-
-            Constraints::with_selector(q_s4, Some(("init_y_q_check", init_y_q_check)))
-        });
-
-        // Check that the initial x_A, x_P, lambda_1, lambda_2 are consistent with y_Q.
-        // https://p.z.cash/halo2-0.1:sinsemilla-constraints?partial
-        meta.create_gate("Initial y_Q (private)", |meta| {
-            let q_s4 = meta.query_selector(config.q_sinsemilla4_private);
             let y_q = meta.query_advice(config.double_and_add.x_p, Rotation::prev());
 
             // Y_A = (lambda_1 + lambda_2) * (x_a - x_r)

halo2_gadgets/src/sinsemilla/chip/hash_to_point.rs

@@ -168,16 +168,17 @@ where
     #[allow(non_snake_case)]
     /// Assign the coordinates of the initial public point `Q`
     ///
-    /// | offset | x_A | q_sinsemilla4 | fixed_y_Q |
-    /// --------------------------------------------
-    /// |   0    | x_Q |       1       |    y_Q    |
+    /// | offset | x_A | x_P | q_sinsemilla4 |
+    /// --------------------------------------
+    /// |   0    |     | y_Q |               |
+    /// |   1    | x_Q |     |       1       |
     fn public_initialization(
         &self,
         region: &mut Region<'_, pallas::Base>,
         Q: pallas::Affine,
     ) -> Result<(usize, X<pallas::Base>, Y<pallas::Base>), Error> {
         let config = self.config().clone();
-        let offset = 0;
+        let mut offset = 0;
 
         // Get the `x`- and `y`-coordinates of the starting `Q` base.
         let x_q = *Q.coordinates().unwrap().x();
@@ -186,17 +187,19 @@ where
         // Constrain the initial x_a, lambda_1, lambda_2, x_p using the q_sinsemilla4
         // selector.
         let y_a: Y<pallas::Base> = {
-            // Enable `q_sinsemilla4` on the first row.
-            config.q_sinsemilla4.enable(region, offset)?;
-            region.assign_fixed(
-                || "fixed y_q",
-                config.fixed_y_q,
-                offset,
-                || Value::known(y_q),
-            )?;
+            // Enable `q_sinsemilla4` on the second row.
+            config.q_sinsemilla4.enable(region, offset + 1)?;
+            let y_a: AssignedCell<Assigned<pallas::Base>, pallas::Base> = region
+                .assign_advice_from_constant(
+                    || "fixed y_q",
+                    config.double_and_add.x_p,
+                    offset,
+                    y_q.into(),
+                )?;
 
-            Value::known(y_q.into()).into()
+            y_a.value_field().into()
         };
+        offset += 1;
 
         // Constrain the initial x_q to equal the x-coordinate of the domain's `Q`.
         let x_a: X<pallas::Base> = {
@@ -216,10 +219,10 @@ where
     #[allow(non_snake_case)]
     /// Assign the coordinates of the initial private point `Q`
     ///
-    /// | offset | x_A | x_P | q_sinsemilla4_private |
-    /// -----------------------------------------------
-    /// |   0    |     | y_Q |                       |
-    /// |   1    | x_Q |     |         1             |
+    /// | offset | x_A | x_P | q_sinsemilla4 |
+    /// --------------------------------------
+    /// |   0    |     | y_Q |               |
+    /// |   1    | x_Q |     |         1     |
     fn private_initialization(
         &self,
         region: &mut Region<'_, pallas::Base>,
@@ -229,10 +232,10 @@ where
         let mut offset = 0;
 
         // Assign `x_Q` and `y_Q` in the region and constrain the initial x_a, lambda_1, lambda_2,
-        // x_p, y_Q using the q_sinsemilla4_private selector.
+        // x_p, y_Q using the q_sinsemilla4 selector.
         let y_a: Y<pallas::Base> = {
-            // Enable `q_sinsemilla4_private` on the first row.
-            config.q_sinsemilla4_private.enable(region, offset + 1)?;
+            // Enable `q_sinsemilla4` on the second row.
+            config.q_sinsemilla4.enable(region, offset + 1)?;
             let q_y: AssignedCell<Assigned<pallas::Base>, pallas::Base> = Q.y().into();
             let y_a: AssignedCell<Assigned<pallas::Base>, pallas::Base> =
                 q_y.copy_advice(|| "fixed y_q", region, config.double_and_add.x_p, offset)?;