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Merged
TomAFrench merged 4 commits into from
Jul 16, 2025
Merged

chore: simplify add and sub #84

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a6ea8b1
simply add and sub
jialinli98 Jul 7, 2025
cb7d63c
add testing
jialinli98 Jul 9, 2025
fbffb7b
merge conflict
jialinli98 Jul 10, 2025
0a28ea5
Merge branch 'main' into jl/point_addition
TomAFrench Jul 16, 2025
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141 changes: 140 additions & 1 deletion src/bigcurve_test.nr
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -322,7 +322,7 @@ fn test_incomplete_add_with_hint() {
}

#[test]
fn test_add() {
fn test_constrained_add() {
unsafe {
let P = BN254::one();

Expand Down Expand Up @@ -380,6 +380,73 @@ fn test_add() {
}
}

#[test]
unconstrained fn test_unconstrained_add() {
let P = BN254::one();

// Q = 2P
let Q = BN254 {
x: BN254_Fq::from_limbs([
0x7816a916871ca8d3c208c16d87cfd3,
0x44e72e131a029b85045b68181585d9,
0x0306,
]),
y: BN254_Fq::from_limbs([
0xa6a449e3538fc7ff3ebf7a5a18a2c4,
0x738c0e0a7c92e7845f96b2ae9c0a68,
0x15ed,
]),
is_infinity: false,
};

let result = BN254J::from(P.add(Q));

let P_j = BN254J::from(P);
let Q_j = BN254J::from(Q);
let expected = P_j.add(Q_j).0;

assert(result.eq(expected));
}
#[test]
unconstrained fn test_unconstrained_add_one_side_infinity() {
//Q + infinity and infinity + Q
let Q = BN254::one();
let P = BN254::point_at_infinity();
let expected = BN254J::from(Q);
let result = BN254J::from(Q.add(P));
assert(result.eq(expected));
let result = BN254J::from(P.add(Q));
assert(result.eq(expected));
}

#[test]
unconstrained fn test_unconstrained_add_doubling() {
// P + P
let P = BN254::one();
let Q = BN254::one();
let P_j = BN254J::from(P);
let result = BN254J::from(P.add(Q));
let expected = P_j.dbl().0;
assert(result.eq(expected));
}

#[test]
unconstrained fn test_unconstrained_add_infinity() {
// P = -Q
let P = BN254::one();
let Q = P.neg();
let result = BN254J::from(P.add(Q));
let expected = BN254J::point_at_infinity();
assert(result.eq(expected));

// both at infinity
let P = BN254::point_at_infinity();
let Q = BN254::point_at_infinity();
let result = BN254J::from(Q.add(P));
let expected = BN254J::point_at_infinity();
assert(result.eq(expected));
}

#[test]
fn test_sub() {
unsafe {
Expand Down Expand Up @@ -439,6 +506,78 @@ fn test_sub() {
}
}

#[test]
unconstrained fn test_unconstrained_sub() {
let P = BN254::one();

// Q = 2P
let Q = BN254 {
x: BN254_Fq::from_limbs([
0x7816a916871ca8d3c208c16d87cfd3,
0x44e72e131a029b85045b68181585d9,
0x0306,
]),
y: BN254_Fq::from_limbs([
0xa6a449e3538fc7ff3ebf7a5a18a2c4,
0x738c0e0a7c92e7845f96b2ae9c0a68,
0x15ed,
]),
is_infinity: false,
};

let result = BN254J::from(P.sub(Q));

let P_j = BN254J::from(P);
let Q_j = BN254J::from(Q);
let expected = P_j.sub(Q_j).0;

assert(result.eq(expected));
}

#[test]
unconstrained fn test_unconstrained_sub_doubling() {
// doubling
let P = BN254::one();
let Q = BN254::one();

let result = BN254J::from(P.sub(Q.neg()));
let P_j = BN254J::from(P);
let expected = P_j.dbl().0;
assert(result.eq(expected));
}

#[test]
unconstrained fn test_unconstrained_sub_infinity() {
// both at infinity
let P = BN254::one();
let Q = BN254::one();
let result = BN254J::from(P.sub(Q));
let expected = BN254J::point_at_infinity();
assert(result.eq(expected));
// both infinity
let P = BN254::point_at_infinity();
let Q = BN254::point_at_infinity();
let result = BN254J::from(Q.sub(P));
let expected = BN254J::point_at_infinity();
assert(result.eq(expected));
}

#[test]
unconstrained fn test_unconstrained_sub_one_side_infinity() {
let P = BN254::point_at_infinity();
let Q = BN254::one();

// lhs infinity
let result = BN254J::from(P.sub(Q));
let expected = BN254J::from(Q.neg());
assert(result.eq(expected));

// rhs infinity
let result = BN254J::from(Q.sub(P));
let expected = expected.neg();
assert(result.eq(expected));
}

#[test]
fn test_make_table() {
unsafe {
Expand Down
9 changes: 7 additions & 2 deletions src/curve_jac.nr
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -304,6 +304,7 @@ where
let y_equal_predicate = S2.eq(S1);
let lhs_infinity = self.is_infinity;
let rhs_infinity = p2.is_infinity;

let double_predicate =
x_equal_predicate & y_equal_predicate & !lhs_infinity & !rhs_infinity;
let add_predicate = !x_equal_predicate & !lhs_infinity & !rhs_infinity;
Expand All @@ -317,9 +318,13 @@ where
} else if (infinity_predicate) {
result = (CurveJ::point_at_infinity(), JTranscript::new());
} else if (lhs_infinity & !rhs_infinity) {
result = (p2, JTranscript::new());
let new_transcript =
JTranscript { x3: p2.x, y3: p2.y, z3: p2.z, lambda_numerator: B::zero() };
result = (p2, new_transcript);
} else if (rhs_infinity & !lhs_infinity) {
result = (self, JTranscript::new());
let new_transcript =
JTranscript { x3: self.x, y3: self.y, z3: self.z, lambda_numerator: B::zero() };
result = (self, new_transcript);
}
result
// let (_, PP): (B, B ) = B::compute_quadratic_expression([[U2, U1]], [[false, true]], [[U2, U1]], [[false, true]], [], []);
Expand Down
45 changes: 27 additions & 18 deletions src/lib.nr
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Original file line number Diff line number Diff line change
Expand Up @@ -184,12 +184,16 @@ pub comptime fn derive_curve_impl(
// Expensive witness generation! Avoid if possible
impl std::ops::Add for $typ {
fn add(self, other: Self) -> Self {
let lhsJ = $CurveJ::<$field_type, $typ>::from(self);
let rhsJ = $CurveJ::<$field_type, $typ>::from(other);

let transcript = unsafe { $AffineTranscript::from_j(lhsJ.add(rhsJ).1) };

$crate::add_with_hint::<$field_type, $typ>(self,other, transcript)
let lhsJ = $crate::curve_jac::CurveJ::<$field_type, $typ>::from(self);
let rhsJ = $crate::curve_jac::CurveJ::<$field_type, $typ>::from(other);
let (result_jac, j_transcript) = unsafe { lhsJ.add(rhsJ) };
let transcript = unsafe { $crate::curve_jac::AffineTranscript::from_j(j_transcript) };
if std::runtime::is_unconstrained() {
$typ::from_coordinates(transcript.x3, transcript.y3, result_jac.is_infinity)

} else {
$crate::add_with_hint::<$field_type, $typ>(self, other, transcript)
}
}
}

Expand All @@ -204,12 +208,17 @@ pub comptime fn derive_curve_impl(

impl std::ops::Sub for $typ {
fn sub(self, other: Self) -> Self {
let lhsJ = $CurveJ::<$field_type, $typ>::from(self);
let rhsJ = $CurveJ::<$field_type, $typ>::from(other);

let transcript = unsafe { $AffineTranscript::from_j(lhsJ.sub(rhsJ).1) };

$crate::sub_with_hint::<$field_type, $typ>(self, other, transcript)
let lhsJ = $crate::curve_jac::CurveJ::<$field_type, $typ>::from(self);
let rhsJ = $crate::curve_jac::CurveJ::<$field_type, $typ>::from(other);
let (result_jac, j_transcript) = unsafe { lhsJ.sub(rhsJ) };

// Convert back to affine coordinates using the transcript
let transcript = unsafe { $crate::curve_jac::AffineTranscript::from_j(j_transcript) };
if std::runtime::is_unconstrained() {
$typ::from_coordinates(transcript.x3, transcript.y3, result_jac.is_infinity)
} else {
$crate::sub_with_hint::<$field_type, $typ>(self, other, transcript)
}
}
}

Expand Down Expand Up @@ -549,10 +558,10 @@ pub(crate) fn add_with_hint<B: BigNum, P: BigCurve<B>>(

// If we are skipping the evaluation of a group operation (x2 == x1, y2 == -y1 OR any input points are at infinity),
// set input operands to 0!
let (x1, y1, x2, y2) = if evaluate_group_operation_predicate {
(x1, y1, x2, y2)
let (x1, y1, x2, y2, x3, y3) = if evaluate_group_operation_predicate {
(x1, y1, x2, y2, x3, y3)
} else {
(B::zero(), B::zero(), B::zero(), B::zero())
(B::zero(), B::zero(), B::zero(), B::zero(), B::zero(), B::zero())
};

// lambda * 2y - 3x * x = 0
Expand Down Expand Up @@ -678,10 +687,10 @@ pub(crate) fn sub_with_hint<B: BigNum, P: BigCurve<B>>(

// If we are skipping the evaluation of a group operation (x2 == x1, y2 == -y1 OR any input points are at infinity),
// set input operands to 0!
let (x1, y1, x2, y2) = if evaluate_group_operation_predicate {
(x1, y1, x2, y2)
let (x1, y1, x2, y2, x3, y3) = if evaluate_group_operation_predicate {
(x1, y1, x2, y2, x3, y3)
} else {
(B::zero(), B::zero(), B::zero(), B::zero())
(B::zero(), B::zero(), B::zero(), B::zero(), B::zero(), B::zero())
};

// lambda * 2y - 3x*x = 0
Expand Down