WIP

barretenberg/cpp/src/barretenberg/ecc/curves/bn254/c_bind.cpp

@@ -0,0 +1,33 @@
+#include "../bn254/fq.hpp"
+#include "../bn254/fr.hpp"
+#include "barretenberg/common/wasm_export.hpp"
+
+using namespace bb;
+
+WASM_EXPORT void bn254_fr_sqrt(uint8_t const* input, uint8_t* result)
+{
+    using serialize::write;
+    auto input_fr = from_buffer<bb::fr>(input);
+    auto [is_sqr, root] = input_fr.sqrt();
+
+    uint8_t* is_sqrt_result_ptr = result;
+    uint8_t* root_result_ptr = result + 1;
+
+    write(is_sqrt_result_ptr, is_sqr);
+    write(root_result_ptr, root);
+}
+
+WASM_EXPORT void bn254_fq_sqrt(uint8_t const* input, uint8_t* result)
+{
+    using serialize::write;
+    auto input_fq = from_buffer<bb::fq>(input);
+    auto [is_sqr, root] = input_fq.sqrt();
+
+    uint8_t* is_sqrt_result_ptr = result;
+    uint8_t* root_result_ptr = result + 1;
+
+    write(is_sqrt_result_ptr, is_sqr);
+    write(root_result_ptr, root);
+}
+
+// NOLINTEND(cert-dcl37-c, cert-dcl51-cpp, bugprone-reserved-identifier)

barretenberg/cpp/src/barretenberg/ecc/curves/grumpkin/c_bind.cpp

@@ -63,17 +63,4 @@ WASM_EXPORT void ecc_grumpkin__reduce512_buffer_mod_circuit_modulus(uint8_t* inp
     write(result, target_output.lo);
 }
 
-WASM_EXPORT void grumpkin_fr_sqrt(uint8_t const* input, uint8_t* result)
-{
-    using serialize::write;
-    auto input_fr = from_buffer<grumpkin::fr>(input);
-    auto [is_sqr, root] = input_fr.sqrt();
-
-    uint8_t* is_sqrt_result_ptr = result;
-    uint8_t* root_result_ptr = result + 1;
-
-    write(is_sqrt_result_ptr, is_sqr);
-    write(root_result_ptr, root);
-}
-
 // NOLINTEND(cert-dcl37-c, cert-dcl51-cpp, bugprone-reserved-identifier)

yarn-project/foundation/src/fields/fields.test.ts

@@ -1,4 +1,4 @@
-import { Fr, GrumpkinScalar } from './fields.js';
+import { Fq, Fr, GrumpkinScalar } from './fields.js';
 
 describe('GrumpkinScalar Serialization', () => {
   // Test case for GrumpkinScalar.fromHighLow
@@ -185,12 +185,20 @@ describe('Bn254 arithmetic', () => {
   });
 
   describe('Square root', () => {
-    it('Should return the correct square root', () => {
-      const a = new Fr(16);
-      const expected = new Fr(4);
+    it('Should return the correct square root for Fr', () => {
+      const a = Fr.random();
+      const squared = a.mul(a);
 
-      const actual = a.sqrt();
-      expect(actual).toEqual(expected);
+      const actual = squared.sqrt();
+      expect(actual!.mul(actual!)).toEqual(squared);
+    });
+
+    it('Should return the correct square root for Fq', () => {
+      const a = Fq.random();
+      const squared = a.mul(a);
+
+      const actual = squared.sqrt();
+      expect(actual!.mul(actual!)).toEqual(squared);
     });
   });
 

yarn-project/foundation/src/fields/fields.ts

@@ -283,21 +283,21 @@ export class Fr extends BaseField {
   }
 
   /**
-   * Computes the square root of the field element.
-   * @returns The square root of the field element (null if it does not exist).
+   * Computes a square root of the field element.
+   * @returns A square root of the field element (null if it does not exist).
    */
   sqrt(): Fr | null {
     const wasm = BarretenbergSync.getSingleton().getWasm();
     wasm.writeMemory(0, this.toBuffer());
-    wasm.call('grumpkin_fr_sqrt', 0, Fr.SIZE_IN_BYTES);
+    wasm.call('bn254_fr_sqrt', 0, Fr.SIZE_IN_BYTES);
     const isSqrtBuf = Buffer.from(wasm.getMemorySlice(Fr.SIZE_IN_BYTES, Fr.SIZE_IN_BYTES + 1));
     const isSqrt = isSqrtBuf[0] === 1;
     if (!isSqrt) {
       // Field element is not a quadratic residue mod p so it has no square root.
       return null;
     }
 
-    const rootBuf = Buffer.from(wasm.getMemorySlice(Fr.SIZE_IN_BYTES + 1, Fr.SIZE_IN_BYTES * 2 + 1))
+    const rootBuf = Buffer.from(wasm.getMemorySlice(Fr.SIZE_IN_BYTES + 1, Fr.SIZE_IN_BYTES * 2 + 1));
     return Fr.fromBuffer(rootBuf);
   }
 
@@ -380,6 +380,29 @@ export class Fq extends BaseField {
     return new Fq((high.toBigInt() << Fq.HIGH_SHIFT) + low.toBigInt());
   }
 
+  mul(rhs: Fq) {
+    return new Fq((this.toBigInt() * rhs.toBigInt()) % Fq.MODULUS);
+  }
+
+  /**
+   * Computes a square root of the field element.
+   * @returns A square root of the field element (null if it does not exist).
+   */
+  sqrt(): Fq | null {
+    const wasm = BarretenbergSync.getSingleton().getWasm();
+    wasm.writeMemory(0, this.toBuffer());
+    wasm.call('bn254_fq_sqrt', 0, Fq.SIZE_IN_BYTES);
+    const isSqrtBuf = Buffer.from(wasm.getMemorySlice(Fq.SIZE_IN_BYTES, Fq.SIZE_IN_BYTES + 1));
+    const isSqrt = isSqrtBuf[0] === 1;
+    if (!isSqrt) {
+      // Field element is not a quadratic residue mod p so it has no square root.
+      return null;
+    }
+
+    const rootBuf = Buffer.from(wasm.getMemorySlice(Fq.SIZE_IN_BYTES + 1, Fq.SIZE_IN_BYTES * 2 + 1));
+    return Fq.fromBuffer(rootBuf);
+  }
+
   toJSON() {
     return {
       type: 'Fq',