chore: ecc group audit 1- remove dead code, documentation and test

barretenberg/cpp/src/barretenberg/ecc/groups/affine_element.hpp

@@ -17,6 +17,11 @@
 #include <vector>
 
 namespace bb::group_elements {
+
+// MSB of the top 64-bit limb in a uint256_t (bit 255). Used in point compression to encode the
+// y-coordinate parity bit, and cleared when recovering the x-coordinate.
+static constexpr uint64_t UINT256_TOP_LIMB_MSB = 0x8000000000000000ULL;
+
 template <typename T>
 concept SupportsHashToCurve = T::can_hash_to_curve;
 template <typename Fq_, typename Fr_, typename Params_> class alignas(64) affine_element {
@@ -80,10 +85,6 @@ template <typename Fq_, typename Fr_, typename Params_> class alignas(64) affine
 
     constexpr affine_element operator*(const Fr& exponent) const noexcept;
 
-    template <typename BaseField = Fq,
-              typename CompileTimeEnabled = std::enable_if_t<(BaseField::modulus >> 255) == uint256_t(0), void>>
-    [[nodiscard]] constexpr uint256_t compress() const noexcept;
-
     static constexpr affine_element infinity();
     constexpr affine_element set_infinity() const noexcept;
     constexpr void self_set_infinity() noexcept;

barretenberg/cpp/src/barretenberg/ecc/groups/affine_element.test.cpp

@@ -139,7 +139,10 @@ template <typename G1> class TestAffineElement : public testing::Test {
     {
         for (size_t i = 0; i < 10; i++) {
             affine_element P = affine_element(element::random_element());
-            uint256_t compressed = P.compress();
+            uint256_t compressed = uint256_t(P.x);
+            if (uint256_t(P.y).get_bit(0)) {
+                compressed.data[3] |= group_elements::UINT256_TOP_LIMB_MSB;
+            }
             affine_element Q = affine_element::from_compressed(compressed);
             EXPECT_EQ(P, Q);
         }
@@ -168,8 +171,6 @@ template <typename G1> class TestAffineElement : public testing::Test {
         affine_element R(0, P.y);
         ASSERT_FALSE(P == R);
     }
-    // Regression test to ensure that the point at infinity is not equal to its coordinate-wise reduction, which may lie
-    // on the curve, depending on the y-coordinate.
     static void test_infinity_ordering_regression()
     {
         affine_element P(0, 1);

barretenberg/cpp/src/barretenberg/ecc/groups/affine_element_impl.hpp

@@ -21,7 +21,7 @@ template <typename BaseField, typename CompileTimeEnabled>
 constexpr affine_element<Fq, Fr, T> affine_element<Fq, Fr, T>::from_compressed(const uint256_t& compressed) noexcept
 {
     uint256_t x_coordinate = compressed;
-    x_coordinate.data[3] = x_coordinate.data[3] & (~0x8000000000000000ULL);
+    x_coordinate.data[3] = x_coordinate.data[3] & (~UINT256_TOP_LIMB_MSB);
     bool y_bit = compressed.get_bit(255);
 
     Fq x = Fq(x_coordinate);
@@ -80,18 +80,6 @@ constexpr affine_element<Fq, Fr, T> affine_element<Fq, Fr, T>::operator*(const F
     return bb::group_elements::element(*this) * exponent;
 }
 
-template <class Fq, class Fr, class T>
-template <typename BaseField, typename CompileTimeEnabled>
-
-constexpr uint256_t affine_element<Fq, Fr, T>::compress() const noexcept
-{
-    uint256_t out(x);
-    if (uint256_t(y).get_bit(0)) {
-        out.data[3] = out.data[3] | 0x8000000000000000ULL;
-    }
-    return out;
-}
-
 template <class Fq, class Fr, class T> constexpr affine_element<Fq, Fr, T> affine_element<Fq, Fr, T>::infinity()
 {
     affine_element e{};
@@ -157,15 +145,9 @@ constexpr bool affine_element<Fq, Fr, T>::operator==(const affine_element& other
     return !only_one_is_infinity && (both_infinity || ((x == other.x) && (y == other.y)));
 }
 
-/**
- * Comparison operators (for std::sort)
- *
- * @details CAUTION!! Don't use this operator. It has no meaning other than for use by std::sort.
- **/
 template <class Fq, class Fr, class T>
 constexpr bool affine_element<Fq, Fr, T>::operator>(const affine_element& other) const noexcept
 {
-    // We are setting point at infinity to always be the lowest element
     if (is_point_at_infinity()) {
         return false;
     }

barretenberg/cpp/src/barretenberg/ecc/groups/element.hpp

@@ -59,7 +59,6 @@ template <class Fq, class Fr, class Params> class alignas(32) element {
 
     constexpr element dbl() const noexcept;
     constexpr void self_dbl() noexcept;
-    constexpr void self_mixed_add_or_sub(const affine_element<Fq, Fr, Params>& other, uint64_t predicate) noexcept;
 
     constexpr element operator+(const element& other) const noexcept;
     constexpr element operator+(const affine_element<Fq, Fr, Params>& other) const noexcept;
@@ -128,27 +127,6 @@ template <class Fq, class Fr, class Params> class alignas(32) element {
 
     template <typename = typename std::enable_if<Params::can_hash_to_curve>>
     static element random_coordinates_on_curve(numeric::RNG* engine = nullptr) noexcept;
-    // {
-    //     bool found_one = false;
-    //     Fq yy;
-    //     Fq x;
-    //     Fq y;
-    //     Fq t0;
-    //     while (!found_one) {
-    //         x = Fq::random_element(engine);
-    //         yy = x.sqr() * x + Params::b;
-    //         if constexpr (Params::has_a) {
-    //             yy += (x * Params::a);
-    //         }
-    //         y = yy.sqrt();
-    //         t0 = y.sqr();
-    //         found_one = (yy == t0);
-    //     }
-    //     return { x, y, Fq::one() };
-    // }
-    static void conditional_negate_affine(const affine_element<Fq, Fr, Params>& in,
-                                          affine_element<Fq, Fr, Params>& out,
-                                          uint64_t predicate) noexcept;
 
     friend std::ostream& operator<<(std::ostream& os, const element& a)
     {
@@ -162,10 +140,6 @@ template <class Fq, class Fr, class Params> std::ostream& operator<<(std::ostrea
     return os << "x:" << e.x << " y:" << e.y << " z:" << e.z;
 }
 
-// constexpr element<Fq, Fr, Params>::one = element<Fq, Fr, Params>{ Params::one_x, Params::one_y, Fq::one() };
-// constexpr element<Fq, Fr, Params>::point_at_infinity = one.set_infinity();
-// constexpr element<Fq, Fr, Params>::curve_b = Params::b;
-
 } // namespace bb::group_elements
 
 #include "./element_impl.hpp"

barretenberg/cpp/src/barretenberg/ecc/groups/element_impl.hpp

@@ -155,99 +155,6 @@ template <class Fq, class Fr, class T> constexpr element<Fq, Fr, T> element<Fq,
     return result;
 }
 
-template <class Fq, class Fr, class T>
-constexpr void element<Fq, Fr, T>::self_mixed_add_or_sub(const affine_element<Fq, Fr, T>& other,
-                                                         const uint64_t predicate) noexcept
-{
-    if constexpr (Fq::modulus.data[3] >= MODULUS_TOP_LIMB_LARGE_THRESHOLD) {
-        if (is_point_at_infinity()) {
-            conditional_negate_affine(other, *(affine_element<Fq, Fr, T>*)this, predicate); // NOLINT
-            z = Fq::one();
-            return;
-        }
-    } else {
-        const bool edge_case_trigger = x.is_msb_set() || other.x.is_msb_set();
-        if (edge_case_trigger) {
-            if (x.is_msb_set()) {
-                conditional_negate_affine(other, *(affine_element<Fq, Fr, T>*)this, predicate); // NOLINT
-                z = Fq::one();
-            }
-            return;
-        }
-    }
-
-    // T0 = z1.z1
-    Fq T0 = z.sqr();
-
-    // T1 = x2.t0 - x1 = x2.z1.z1 - x1
-    Fq T1 = other.x * T0;
-    T1 -= x;
-
-    // T2 = T0.z1 = z1.z1.z1
-    // T2 = T2.y2 - y1 = y2.z1.z1.z1 - y1
-    Fq T2 = z * T0;
-    T2 *= other.y;
-    T2.self_conditional_negate(predicate);
-    T2 -= y;
-
-    if (__builtin_expect(T1.is_zero(), 0)) {
-        if (T2.is_zero()) {
-            // y2 equals y1, x2 equals x1, double x1
-            self_dbl();
-            return;
-        }
-        self_set_infinity();
-        return;
-    }
-
-    // T2 = 2T2 = 2(y2.z1.z1.z1 - y1) = R
-    // z3 = z1 + H
-    T2 += T2;
-    z += T1;
-
-    // T3 = T1*T1 = HH
-    Fq T3 = T1.sqr();
-
-    // z3 = z3 - z1z1 - HH
-    T0 += T3;
-
-    // z3 = (z1 + H)*(z1 + H)
-    z.self_sqr();
-    z -= T0;
-
-    // T3 = 4HH
-    T3 += T3;
-    T3 += T3;
-
-    // T1 = T1*T3 = 4HHH
-    T1 *= T3;
-
-    // T3 = T3 * x1 = 4HH*x1
-    T3 *= x;
-
-    // T0 = 2T3
-    T0 = T3 + T3;
-
-    // T0 = T0 + T1 = 2(4HH*x1) + 4HHH
-    T0 += T1;
-    x = T2.sqr();
-
-    // x3 = x3 - T0 = R*R - 8HH*x1 -4HHH
-    x -= T0;
-
-    // T3 = T3 - x3 = 4HH*x1 - x3
-    T3 -= x;
-
-    T1 *= y;
-    T1 += T1;
-
-    // T3 = T2 * T3 = R*(4HH*x1 - x3)
-    T3 *= T2;
-
-    // y3 = T3 - T1
-    y = T3 - T1;
-}
-
 template <class Fq, class Fr, class T>
 constexpr element<Fq, Fr, T> element<Fq, Fr, T>::operator+=(const affine_element<Fq, Fr, T>& other) noexcept
 {
@@ -1057,14 +964,6 @@ std::vector<affine_element<Fq, Fr, T>> element<Fq, Fr, T>::batch_mul_with_endomo
     return work_elements;
 }
 
-template <typename Fq, typename Fr, typename T>
-void element<Fq, Fr, T>::conditional_negate_affine(const affine_element<Fq, Fr, T>& in,
-                                                   affine_element<Fq, Fr, T>& out,
-                                                   const uint64_t predicate) noexcept
-{
-    out = { in.x, predicate ? -in.y : in.y };
-}
-
 template <typename Fq, typename Fr, typename T>
 void element<Fq, Fr, T>::batch_normalize(element* elements, const size_t num_elements) noexcept
 {

barretenberg/cpp/src/barretenberg/ecc/groups/group.hpp

@@ -130,16 +130,6 @@ template <typename Fq_, typename Fr_, typename Params> class group {
         }
         return derive_generators(domain_bytes, num_generators, starting_index);
     }
-
-    BB_INLINE static void conditional_negate_affine(const affine_element* src,
-                                                    affine_element* dest,
-                                                    uint64_t predicate);
 };
 
 } // namespace bb
-
-#ifdef DISABLE_ASM
-#include "group_impl_int128.tcc"
-#else
-#include "group_impl_asm.tcc"
-#endif