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feat: add checks on input values in ec operations (#963)
* feat: add checks on input values in ec operations * remove scalar check in ec_mul
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,107 @@ | ||
| pub(crate) mod ec_add; | ||
| pub(crate) mod ec_mul; | ||
| use core::circuit::CircuitElement as CE; | ||
| use core::circuit::CircuitInput as CI; | ||
| use core::circuit::{ | ||
| u96, u384, CircuitElement, CircuitInput, circuit_add, circuit_sub, circuit_mul, circuit_inverse, | ||
| EvalCircuitTrait, CircuitOutputsTrait, CircuitModulus, CircuitInputs | ||
| }; | ||
| use core::num::traits::Zero; | ||
| use garaga::core::circuit::AddInputResultTrait2; | ||
|
|
||
| const BN254_ORDER: u256 = 0x30644E72E131A029B85045B68181585D2833E84879B9709143E1F593F0000001; | ||
| const BN254_PRIME: u256 = 0x30644e72e131a029b85045b68181585d97816a916871ca8d3c208c16d87cfd47; | ||
| const BN254_PRIME_LIMBS: [ | ||
| u96 | ||
| ; 4] = [ | ||
| 0x6871ca8d3c208c16d87cfd47, 0xb85045b68181585d97816a91, 0x30644e72e131a029, 0x0 | ||
| ]; | ||
|
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||
| // Check if a point is on the curve. | ||
| // Point at infinity (0,0) will return false. | ||
| pub fn is_on_curve(x: u384, y: u384) -> bool { | ||
| let (b, _x, _y) = (CE::<CI<0>> {}, CE::<CI<1>> {}, CE::<CI<2>> {}); | ||
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| // Compute (y^2 - (x^3 + b)) % p_bn254 | ||
| let x2 = circuit_mul(_x, _x); | ||
| let x3 = circuit_mul(x2, _x); | ||
| let y2 = circuit_mul(_y, _y); | ||
| let rhs = circuit_add(x3, b); | ||
| let check = circuit_sub(y2, rhs); | ||
|
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||
| let modulus = TryInto::<_, CircuitModulus>::try_into(BN254_PRIME_LIMBS) | ||
| .unwrap(); // BN254 prime field modulus | ||
|
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| let mut circuit_inputs = (check,).new_inputs(); | ||
| // Prefill constants: | ||
| circuit_inputs = circuit_inputs.next_2([3, 0, 0, 0]); | ||
| // Fill inputs: | ||
| circuit_inputs = circuit_inputs.next_2(x); | ||
| circuit_inputs = circuit_inputs.next_2(y); | ||
|
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| let outputs = circuit_inputs.done_2().eval(modulus).unwrap(); | ||
| let zero_check: u384 = outputs.get_output(check); | ||
| return zero_check.is_zero(); | ||
| } | ||
|
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| // Double BN254 EC point without checking if the point is on the curve | ||
| pub fn double_ec_point_unchecked(x: u384, y: u384) -> (u384, u384) { | ||
| // CONSTANT stack | ||
| let in0 = CE::<CI<0>> {}; // 0x3 | ||
| // INPUT stack | ||
| let (_x, _y) = (CE::<CI<1>> {}, CE::<CI<2>> {}); | ||
|
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||
| let x2 = circuit_mul(_x, _x); | ||
| let num = circuit_mul(in0, x2); | ||
| let den = circuit_add(_y, _y); | ||
| let inv_den = circuit_inverse(den); | ||
| let slope = circuit_mul(num, inv_den); | ||
| let slope_sqr = circuit_mul(slope, slope); | ||
|
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| let nx = circuit_sub(circuit_sub(slope_sqr, _x), _x); | ||
| let ny = circuit_sub(circuit_mul(slope, circuit_sub(_x, nx)), _y); | ||
|
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| let modulus = TryInto::<_, CircuitModulus>::try_into(BN254_PRIME_LIMBS) | ||
| .unwrap(); // BN254 prime field modulus | ||
|
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| let mut circuit_inputs = (nx, ny,).new_inputs(); | ||
| // Prefill constants: | ||
| circuit_inputs = circuit_inputs.next_2([0x3, 0x0, 0x0, 0x0]); // in0 | ||
| // Fill inputs: | ||
| circuit_inputs = circuit_inputs.next_2(x); // in1 | ||
| circuit_inputs = circuit_inputs.next_2(y); // in2 | ||
|
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| let outputs = circuit_inputs.done_2().eval(modulus).unwrap(); | ||
|
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| (outputs.get_output(nx), outputs.get_output(ny)) | ||
| } | ||
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| // returns true if a == b mod p_bn254 | ||
| pub fn eq_mod_p(a: u384, b: u384) -> bool { | ||
| let in1 = CircuitElement::<CircuitInput<0>> {}; | ||
| let in2 = CircuitElement::<CircuitInput<1>> {}; | ||
| let sub = circuit_sub(in1, in2); | ||
|
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| let modulus = TryInto::<_, CircuitModulus>::try_into(BN254_PRIME_LIMBS) | ||
| .unwrap(); // BN254 prime field modulus | ||
|
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| let outputs = (sub,).new_inputs().next_2(a).next_2(b).done_2().eval(modulus).unwrap(); | ||
|
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| return outputs.get_output(sub).is_zero(); | ||
| } | ||
|
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| // returns true if a == -b mod p_bn254 | ||
| pub fn eq_neg_mod_p(a: u384, b: u384) -> bool { | ||
| let _a = CE::<CI<0>> {}; | ||
| let _b = CE::<CI<1>> {}; | ||
| let check = circuit_add(_a, _b); | ||
|
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| let modulus = TryInto::<_, CircuitModulus>::try_into(BN254_PRIME_LIMBS) | ||
| .unwrap(); // BN254 prime field modulus | ||
|
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| let outputs = (check,).new_inputs().next_2(a).next_2(b).done_2().eval(modulus).unwrap(); | ||
|
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| return outputs.get_output(check).is_zero(); | ||
| } |
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