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Gadgets for comparing to constant #117

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merged 3 commits into from
Aug 31, 2022
Merged

Gadgets for comparing to constant #117

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8dec7f7
naive implementation
mrain Aug 30, 2022
0651e74
Unified test methods.
mrain Aug 31, 2022
aec0013
comments.
mrain Aug 31, 2022
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193 changes: 192 additions & 1 deletion relation/src/gadgets/cmp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -85,6 +85,93 @@ impl<F: PrimeField> PlonkCircuit<F> {
let c = self.is_lt_internal(a, b)?;
self.logic_neg(c)
}

/// Returns a `BoolVar` indicating whether the variable `a` is less than a
/// given constant `val`.
pub fn is_lt_constant(&mut self, a: Variable, val: F) -> Result<BoolVar, CircuitError>
where
F: PrimeField,
{
self.check_var_bound(a)?;
let b = self.create_constant_variable(val)?;
self.is_lt(a, b)
}

/// Returns a `BoolVar` indicating whether the variable `a` is less than or
/// equal to a given constant `val`.
pub fn is_leq_constant(&mut self, a: Variable, val: F) -> Result<BoolVar, CircuitError>
where
F: PrimeField,
{
self.check_var_bound(a)?;
let b = self.create_constant_variable(val)?;
self.is_leq(a, b)
}

/// Returns a `BoolVar` indicating whether the variable `a` is greater than
/// a given constant `val`.
pub fn is_gt_constant(&mut self, a: Variable, val: F) -> Result<BoolVar, CircuitError>
where
F: PrimeField,
{
self.check_var_bound(a)?;
self.is_gt_constant_internal(a, &val)
}

/// Returns a `BoolVar` indicating whether the variable `a` is greater than
/// or equal a given constant `val`.
pub fn is_geq_constant(&mut self, a: Variable, val: F) -> Result<BoolVar, CircuitError>
where
F: PrimeField,
{
self.check_var_bound(a)?;
let b = self.create_constant_variable(val)?;
self.is_geq(a, b)
}

/// Enforce the variable `a` to be less than a
/// given constant `val`.
pub fn enforce_lt_constant(&mut self, a: Variable, val: F) -> Result<(), CircuitError>
where
F: PrimeField,
{
self.check_var_bound(a)?;
let b = self.create_constant_variable(val)?;
self.enforce_lt(a, b)
}

/// Enforce the variable `a` to be less than or
/// equal to a given constant `val`.
pub fn enforce_leq_constant(&mut self, a: Variable, val: F) -> Result<(), CircuitError>
where
F: PrimeField,
{
self.check_var_bound(a)?;
let b = self.create_constant_variable(val)?;
self.enforce_leq(a, b)
}

/// Enforce the variable `a` to be greater than
/// a given constant `val`.
pub fn enforce_gt_constant(&mut self, a: Variable, val: F) -> Result<(), CircuitError>
where
F: PrimeField,
{
self.check_var_bound(a)?;
let b = self.create_constant_variable(val)?;
self.enforce_gt(a, b)
}

/// Enforce the variable `a` to be greater than
/// or equal a given constant `val`.
pub fn enforce_geq_constant(&mut self, a: Variable, val: F) -> Result<(), CircuitError>
where
F: PrimeField,
{
self.check_var_bound(a)?;
let b = self.create_constant_variable(val)?;
self.enforce_geq(a, b)
}
}

/// Private helper functions for comparison gate
Expand Down Expand Up @@ -216,7 +303,23 @@ mod test {
test_enforce_le(b, a)?;
test_enforce_leq(b, a)?;
test_enforce_ge(b, a)?;
test_enforce_geq(b, a)
test_enforce_geq(b, a)?;
test_is_le_constant(a, b)?;
test_is_leq_constant(a, b)?;
test_is_ge_constant(a, b)?;
test_is_geq_constant(a, b)?;
test_enforce_le_constant(a, b)?;
test_enforce_leq_constant(a, b)?;
test_enforce_ge_constant(a, b)?;
test_enforce_geq_constant(a, b)?;
test_is_le_constant(b, a)?;
test_is_leq_constant(b, a)?;
test_is_ge_constant(b, a)?;
test_is_geq_constant(b, a)?;
test_enforce_le_constant(b, a)?;
test_enforce_leq_constant(b, a)?;
test_enforce_ge_constant(b, a)?;
test_enforce_geq_constant(b, a)
})
}

Expand Down Expand Up @@ -316,4 +419,92 @@ mod test {
}
Ok(())
}
fn test_is_le_constant<F: PrimeField>(a: &F, b: &F) -> Result<(), CircuitError> {
let mut circuit = PlonkCircuit::<F>::new_turbo_plonk();
let expected_result = if a < b { F::one() } else { F::zero() };
let a = circuit.create_variable(*a)?;

let c = circuit.is_lt_constant(a, *b)?;
assert!(circuit.witness(c.into())?.eq(&expected_result));
assert!(circuit.check_circuit_satisfiability(&[]).is_ok());
Ok(())
}
fn test_is_leq_constant<F: PrimeField>(a: &F, b: &F) -> Result<(), CircuitError> {
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let mut circuit = PlonkCircuit::<F>::new_turbo_plonk();
let expected_result = if a <= b { F::one() } else { F::zero() };
let a = circuit.create_variable(*a)?;

let c = circuit.is_leq_constant(a, *b)?;
assert!(circuit.witness(c.into())?.eq(&expected_result));
assert!(circuit.check_circuit_satisfiability(&[]).is_ok());
Ok(())
}
fn test_is_ge_constant<F: PrimeField>(a: &F, b: &F) -> Result<(), CircuitError> {
let mut circuit = PlonkCircuit::<F>::new_turbo_plonk();
let expected_result = if a > b { F::one() } else { F::zero() };
let a = circuit.create_variable(*a)?;

let c = circuit.is_gt_constant(a, *b)?;
assert!(circuit.witness(c.into())?.eq(&expected_result));
assert!(circuit.check_circuit_satisfiability(&[]).is_ok());
Ok(())
}
fn test_is_geq_constant<F: PrimeField>(a: &F, b: &F) -> Result<(), CircuitError> {
let mut circuit = PlonkCircuit::<F>::new_turbo_plonk();
let expected_result = if a >= b { F::one() } else { F::zero() };
let a = circuit.create_variable(*a)?;

let c = circuit.is_geq_constant(a, *b)?;
assert!(circuit.witness(c.into())?.eq(&expected_result));
assert!(circuit.check_circuit_satisfiability(&[]).is_ok());
Ok(())
}
fn test_enforce_le_constant<F: PrimeField>(a: &F, b: &F) -> Result<(), CircuitError> {
let mut circuit = PlonkCircuit::<F>::new_turbo_plonk();
let expected_result = a < b;
let a = circuit.create_variable(*a)?;
circuit.enforce_lt_constant(a, *b)?;
if expected_result {
assert!(circuit.check_circuit_satisfiability(&[]).is_ok())
} else {
assert!(circuit.check_circuit_satisfiability(&[]).is_err());
}
Ok(())
}
fn test_enforce_leq_constant<F: PrimeField>(a: &F, b: &F) -> Result<(), CircuitError> {
let mut circuit = PlonkCircuit::<F>::new_turbo_plonk();
let expected_result = a <= b;
let a = circuit.create_variable(*a)?;
circuit.enforce_leq_constant(a, *b)?;
if expected_result {
assert!(circuit.check_circuit_satisfiability(&[]).is_ok())
} else {
assert!(circuit.check_circuit_satisfiability(&[]).is_err());
}
Ok(())
}
fn test_enforce_ge_constant<F: PrimeField>(a: &F, b: &F) -> Result<(), CircuitError> {
let mut circuit = PlonkCircuit::<F>::new_turbo_plonk();
let expected_result = a > b;
let a = circuit.create_variable(*a)?;
circuit.enforce_gt_constant(a, *b)?;
if expected_result {
assert!(circuit.check_circuit_satisfiability(&[]).is_ok())
} else {
assert!(circuit.check_circuit_satisfiability(&[]).is_err());
}
Ok(())
}
fn test_enforce_geq_constant<F: PrimeField>(a: &F, b: &F) -> Result<(), CircuitError> {
let mut circuit = PlonkCircuit::<F>::new_turbo_plonk();
let expected_result = a >= b;
let a = circuit.create_variable(*a)?;
circuit.enforce_geq_constant(a, *b)?;
if expected_result {
assert!(circuit.check_circuit_satisfiability(&[]).is_ok())
} else {
assert!(circuit.check_circuit_satisfiability(&[]).is_err());
}
Ok(())
}
}