Add constraints for relevant curves (#3)

ed_on_mnt4_298/Cargo.toml

@@ -16,14 +16,18 @@ edition = "2018"
 ark-ff = { git = "https://github.com/arkworks-rs/algebra", default-features = false }
 ark-ec = { git = "https://github.com/arkworks-rs/algebra", default-features = false }
 ark-std = { git = "https://github.com/arkworks-rs/utils", default-features = false }
+ark-r1cs-std = {  git = "https://github.com/arkworks-rs/r1cs-std", default-features = false, optional = true }
 ark-mnt4-298 = { path = "../mnt4_298", default-features = false, features = [ "scalar_field" ] }
 
 [dev-dependencies]
+ark-relations = { git = "https://github.com/arkworks-rs/snark", default-features = false }
 ark-serialize = { git = "https://github.com/arkworks-rs/algebra", default-features = false }
 ark-curve-tests = { path = "../curve-tests", default-features = false }
+ark-curve-constraint-tests = { path = "../curve-constraint-tests", default-features = false }
 rand = { version = "0.7", default-features = false }
 rand_xorshift = "0.2"
 
 [features]
 default = []
 std = [ "ark-std/std", "ark-ff/std", "ark-ec/std", "ark-mnt4-298/std" ]
+r1cs = ["ark-r1cs-std"]

ed_on_mnt4_298/src/constraints/curves.rs

@@ -0,0 +1,12 @@
+use crate::*;
+use ark_r1cs_std::groups::curves::twisted_edwards::AffineVar;
+
+use crate::constraints::fields::FqVar;
+
+/// A variable that is the R1CS equivalent of `crate::EdwardsAffine`.
+pub type EdwardsVar = AffineVar<EdwardsParameters, FqVar>;
+
+#[test]
+fn test() {
+    ark_curve_constraint_tests::curves::te_test::<EdwardsParameters, EdwardsVar>().unwrap();
+}

ed_on_mnt4_298/src/constraints/fields.rs

@@ -0,0 +1,10 @@
+use crate::fq::Fq;
+use ark_r1cs_std::fields::fp::FpVar;
+
+/// A variable that is the R1CS equivalent of `crate::Fq`.
+pub type FqVar = FpVar<Fq>;
+
+#[test]
+fn test() {
+    ark_curve_constraint_tests::fields::field_test::<_, _, FqVar>().unwrap();
+}

ed_on_mnt4_298/src/constraints/mod.rs

@@ -0,0 +1,107 @@
+//! This module implements the R1CS equivalent of `ark_ed_on_mnt4_298`.
+//!
+//! It implements field variables for `crate::Fq`,
+//! and group variables for `crate::GroupProjective`.
+//!
+//! The field underlying these constraints is `crate::Fq`.
+//!
+//! # Examples
+//!
+//! One can perform standard algebraic operations on `FqVar`:
+//!
+//! ```
+//! # fn main() -> Result<(), ark_relations::r1cs::SynthesisError> {
+//! use ark_ff::UniformRand;
+//! use ark_relations::r1cs::*;
+//! use ark_r1cs_std::prelude::*;
+//! use ark_ed_on_mnt4_298::{*, constraints::*};
+//!
+//! let cs = ConstraintSystem::<Fq>::new_ref();
+//! // This rng is just for test purposes; do not use it
+//! // in real applications.
+//! let mut rng = ark_ff::test_rng();
+//!
+//! // Generate some random `Fq` elements.
+//! let a_native = Fq::rand(&mut rng);
+//! let b_native = Fq::rand(&mut rng);
+//!
+//! // Allocate `a_native` and `b_native` as witness variables in `cs`.
+//! let a = FqVar::new_witness(ark_relations::ns!(cs, "generate_a"), || Ok(a_native))?;
+//! let b = FqVar::new_witness(ark_relations::ns!(cs, "generate_b"), || Ok(b_native))?;
+//!
+//! // Allocate `a_native` and `b_native` as constants in `cs`. This does not add any
+//! // constraints or variables.
+//! let a_const = FqVar::new_constant(ark_relations::ns!(cs, "a_as_constant"), a_native)?;
+//! let b_const = FqVar::new_constant(ark_relations::ns!(cs, "b_as_constant"), b_native)?;
+//!
+//! let one = FqVar::one();
+//! let zero = FqVar::zero();
+//!
+//! // Sanity check one + one = two
+//! let two = &one + &one + &zero;
+//! two.enforce_equal(&one.double()?)?;
+//!
+//! assert!(cs.is_satisfied()?);
+//!
+//! // Check that the value of &a + &b is correct.
+//! assert_eq!((&a + &b).value()?, a_native + &b_native);
+//!
+//! // Check that the value of &a * &b is correct.
+//! assert_eq!((&a * &b).value()?, a_native * &b_native);
+//!
+//! // Check that operations on variables and constants are equivalent.
+//! (&a + &b).enforce_equal(&(&a_const + &b_const))?;
+//! assert!(cs.is_satisfied()?);
+//! # Ok(())
+//! # }
+//! ```
+//!
+//! One can also perform standard algebraic operations on `EdwardsVar`:
+//!
+//! ```
+//! # fn main() -> Result<(), ark_relations::r1cs::SynthesisError> {
+//! # use ark_ff::UniformRand;
+//! # use ark_relations::r1cs::*;
+//! # use ark_r1cs_std::prelude::*;
+//! # use ark_ed_on_mnt4_298::{*, constraints::*};
+//!
+//! # let cs = ConstraintSystem::<Fq>::new_ref();
+//! # let mut rng = ark_ff::test_rng();
+//!
+//! // Generate some random `Edwards` elements.
+//! let a_native = EdwardsProjective::rand(&mut rng);
+//! let b_native = EdwardsProjective::rand(&mut rng);
+//!
+//! // Allocate `a_native` and `b_native` as witness variables in `cs`.
+//! let a = EdwardsVar::new_witness(ark_relations::ns!(cs, "a"), || Ok(a_native))?;
+//! let b = EdwardsVar::new_witness(ark_relations::ns!(cs, "b"), || Ok(b_native))?;
+//!
+//! // Allocate `a_native` and `b_native` as constants in `cs`. This does not add any
+//! // constraints or variables.
+//! let a_const = EdwardsVar::new_constant(ark_relations::ns!(cs, "a_as_constant"), a_native)?;
+//! let b_const = EdwardsVar::new_constant(ark_relations::ns!(cs, "b_as_constant"), b_native)?;
+//!
+//! // This returns the identity of `Edwards`.
+//! let zero = EdwardsVar::zero();
+//!
+//! // Sanity check one + one = two
+//! let two_a = &a + &a + &zero;
+//! two_a.enforce_equal(&a.double()?)?;
+//!
+//! assert!(cs.is_satisfied()?);
+//!
+//! // Check that the value of &a + &b is correct.
+//! assert_eq!((&a + &b).value()?, a_native + &b_native);
+//!
+//! // Check that operations on variables and constants are equivalent.
+//! (&a + &b).enforce_equal(&(&a_const + &b_const))?;
+//! assert!(cs.is_satisfied()?);
+//! # Ok(())
+//! # }
+//! ```
+
+mod curves;
+mod fields;
+
+pub use curves::*;
+pub use fields::*;

ed_on_mnt4_298/src/lib.rs

@@ -21,6 +21,8 @@
 //!    * a = -1
 //!    * d = 4212 mod q
 
+#[cfg(feature = "r1cs")]
+pub mod constraints;
 mod curves;
 mod fields;