is_cmp circuit

src/circuits.rs

@@ -7,3 +7,4 @@ pub use werewolf::*;
 pub mod bit_decomposition;
 pub mod enforce_smaller_or_eq_than;
 pub mod equality_zero;
+pub mod smaller_than;

src/circuits/smaller_than.rs

@@ -0,0 +1,40 @@
+use std::cmp::Ordering;
+
+use ark_ff::PrimeField;
+use ark_r1cs_std::alloc::AllocVar;
+use ark_r1cs_std::fields::fp::FpVar;
+use ark_relations::r1cs::{ConstraintSynthesizer, ConstraintSystemRef, SynthesisError};
+use mpc_algebra::malicious_majority::MpcField;
+use mpc_algebra::MpcFpVar;
+
+type Fr = ark_bls12_377::Fr;
+type MFr = MpcField<Fr>;
+
+pub struct LessThanCircuit<F: PrimeField> {
+    pub a: F,
+    pub b: F,
+    pub cmp: Ordering,
+    pub check_eq: bool,
+}
+
+impl ConstraintSynthesizer<MFr> for LessThanCircuit<MFr> {
+    fn generate_constraints(self, cs: ConstraintSystemRef<MFr>) -> Result<(), SynthesisError> {
+        let a_var = MpcFpVar::new_witness(cs.clone(), || Ok(self.a))?;
+        let b_var = MpcFpVar::new_witness(cs, || Ok(self.b))?;
+
+        let _res = MpcFpVar::is_cmp(&a_var, &b_var, self.cmp, self.check_eq).unwrap();
+
+        Ok(())
+    }
+}
+
+impl ConstraintSynthesizer<Fr> for LessThanCircuit<Fr> {
+    fn generate_constraints(self, cs: ConstraintSystemRef<Fr>) -> Result<(), SynthesisError> {
+        let a_var = FpVar::new_witness(cs.clone(), || Ok(self.a))?;
+        let b_var = FpVar::new_witness(cs, || Ok(self.b))?;
+
+        let _res = FpVar::is_cmp(&a_var, &b_var, self.cmp, self.check_eq).unwrap();
+
+        Ok(())
+    }
+}