ECDSA gadget and test

plonky2/src/curve/ecdsa.rs

@@ -1,5 +1,3 @@
-use std::ops::Mul;
-
 use itertools::unfold;
 
 use crate::curve::curve_types::{AffinePoint, Curve, CurveScalar};
@@ -11,8 +9,8 @@ pub struct ECDSASignature<C: Curve> {
     pub s: C::ScalarField,
 }
 
-pub struct ECDSASecretKey<C: Curve>(C::ScalarField);
-pub struct ECDSAPublicKey<C: Curve>(AffinePoint<C>);
+pub struct ECDSASecretKey<C: Curve>(pub C::ScalarField);
+pub struct ECDSAPublicKey<C: Curve>(pub AffinePoint<C>);
 
 pub fn base_to_scalar<C: Curve>(x: C::BaseField) -> C::ScalarField {
     C::ScalarField::from_biguint(x.to_biguint())
@@ -22,15 +20,6 @@ pub fn scalar_to_base<C: Curve>(x: C::ScalarField) -> C::BaseField {
     C::BaseField::from_biguint(x.to_biguint())
 }
 
-pub fn hash_to_scalar<F: RichField, C: Curve>(msg: F, num_bits: usize) -> C::ScalarField {
-    let h_bits = hash_to_bits(msg, num_bits);
-    let h_u32 = h_bits
-        .iter()
-        .zip(0..32)
-        .fold(0u32, |acc, (&bit, pow)| acc + (bit as u32) * (2 << pow));
-    C::ScalarField::from_canonical_u32(h_u32)
-}
-
 pub fn hash_to_bits<F: RichField>(x: F, num_bits: usize) -> Vec<bool> {
     let hashed = hash_n_to_1(vec![x], true);
 
@@ -44,6 +33,15 @@ pub fn hash_to_bits<F: RichField>(x: F, num_bits: usize) -> Vec<bool> {
     .collect()
 }
 
+pub fn hash_to_scalar<F: RichField, C: Curve>(x: F, num_bits: usize) -> C::ScalarField {
+    let h_bits = hash_to_bits(x, num_bits);
+    let h_u32 = h_bits
+        .iter()
+        .zip(0..32)
+        .fold(0u32, |acc, (&bit, pow)| acc + (bit as u32) * (2 << pow));
+    C::ScalarField::from_canonical_u32(h_u32)
+}
+
 pub fn sign_message<F: RichField, C: Curve>(msg: F, sk: ECDSASecretKey<C>) -> ECDSASignature<C> {
     let h = hash_to_scalar::<F, C>(msg, 32);
 
@@ -76,16 +74,14 @@ pub fn verify_message<F: RichField, C: Curve>(
     r == x
 }
 
+#[cfg(test)]
 mod tests {
-    use anyhow::Result;
-
     use crate::curve::curve_types::{Curve, CurveScalar};
     use crate::curve::ecdsa::{sign_message, verify_message, ECDSAPublicKey, ECDSASecretKey};
     use crate::curve::secp256k1::Secp256K1;
     use crate::field::field_types::Field;
     use crate::field::goldilocks_field::GoldilocksField;
     use crate::field::secp256k1_scalar::Secp256K1Scalar;
-    use crate::plonk::circuit_data::CircuitConfig;
 
     #[test]
     fn test_ecdsa_native() {

plonky2/src/gadgets/nonnative.rs

@@ -15,7 +15,7 @@ use crate::plonk::circuit_builder::CircuitBuilder;
 #[derive(Clone, Debug)]
 pub struct NonNativeTarget<FF: Field> {
     pub(crate) value: BigUintTarget,
-    _phantom: PhantomData<FF>,
+    pub(crate) _phantom: PhantomData<FF>,
 }
 
 impl<F: RichField + Extendable<D>, const D: usize> CircuitBuilder<F, D> {

waksman/src/ecdsa.rs

@@ -1,3 +1,15 @@
+use std::marker::PhantomData;
+
+use crate::curve::curve_types::Curve;
+use crate::field::extension_field::Extendable;
+use crate::field::field_types::RichField;
+use crate::gadgets::arithmetic_u32::U32Target;
+use crate::gadgets::biguint::BigUintTarget;
+use crate::gadgets::curve::AffinePointTarget;
+use crate::gadgets::nonnative::NonNativeTarget;
+use crate::iop::target::{BoolTarget, Target};
+use crate::plonk::circuit_builder::CircuitBuilder;
+
 pub struct ECDSASecretKeyTarget<C: Curve>(NonNativeTarget<C::ScalarField>);
 pub struct ECDSAPublicKeyTarget<C: Curve>(AffinePointTarget<C>);
 
@@ -6,48 +18,105 @@ pub struct ECDSASignatureTarget<C: Curve> {
     pub s: NonNativeTarget<C::ScalarField>,
 }
 
-
-
 impl<F: RichField + Extendable<D>, const D: usize> CircuitBuilder<F, D> {
-    
+    pub fn hash_to_bits(&mut self, x: Target, num_bits: usize) -> Vec<BoolTarget> {
+        let inputs = vec![x];
+        let hashed = self.hash_n_to_m(inputs, 1, true)[0];
+        self.split_le(hashed, num_bits)
+    }
+
+    pub fn hash_to_scalar<C: Curve>(&mut self, x: Target, num_bits: usize) -> NonNativeTarget<C::ScalarField> {
+        let h_bits = self.hash_to_bits(x, num_bits);
+        
+        let two = self.two();
+        let mut rev_bits = h_bits.iter().rev();
+        let mut sum = rev_bits.next().unwrap().target;
+        for &bit in rev_bits {
+            sum = self.mul_add(two, sum, bit.target);
+        }
+        let limbs = vec![U32Target(sum)];
+        let value = BigUintTarget {
+            limbs,
+        };
+
+        NonNativeTarget {
+            value,
+            _phantom: PhantomData,
+        }
+    }
+
+    pub fn verify_message<C: Curve>(&mut self, msg: Target, sig: ECDSASignatureTarget<C>, pk: ECDSAPublicKeyTarget<C>) {
+        let ECDSASignatureTarget { r, s } = sig;
+
+        let h = self.hash_to_scalar::<C>(msg, 32);
+
+        let c = self.inv_nonnative(&s);
+        let u1 = self.mul_nonnative(&h, &c);
+        let u2 = self.mul_nonnative(&r, &c);
+
+        let g = self.constant_affine_point(C::GENERATOR_AFFINE);
+        let point1 = self.curve_scalar_mul(&g, &u1);
+        let point2 = self.curve_scalar_mul(&pk.0, &u2);
+        let point = self.curve_add(&point1, &point2);
+
+        let x = NonNativeTarget::<C::ScalarField> {
+            value: point.x.value,
+            _phantom: PhantomData,
+        };
+        self.connect_nonnative(&r, &x);
+    }
 }
 
+#[cfg(test)]
 mod tests {
-    use std::ops::{Mul, Neg};
-
     use anyhow::Result;
 
-    use crate::curve::curve_types::{AffinePoint, Curve, CurveScalar};
+    use crate::curve::curve_types::{Curve, CurveScalar};
+    use crate::curve::ecdsa::{ECDSAPublicKey, ECDSASecretKey, ECDSASignature, sign_message};
     use crate::curve::secp256k1::Secp256K1;
     use crate::field::field_types::Field;
     use crate::field::goldilocks_field::GoldilocksField;
-    use crate::field::secp256k1_base::Secp256K1Base;
     use crate::field::secp256k1_scalar::Secp256K1Scalar;
+    use crate::gadgets::ecdsa::{ECDSAPublicKeyTarget, ECDSASignatureTarget};
     use crate::iop::witness::PartialWitness;
     use crate::plonk::circuit_builder::CircuitBuilder;
     use crate::plonk::circuit_data::CircuitConfig;
     use crate::plonk::verifier::verify;
 
-    /*#[test]
-    fn test_curve_point_is_valid() -> Result<()> {
+    #[test]
+    fn test_ecdsa_circuit() -> Result<()> {
         type F = GoldilocksField;
         const D: usize = 4;
+        type C = Secp256K1;
 
         let config = CircuitConfig::standard_recursion_config();
 
         let pw = PartialWitness::new();
         let mut builder = CircuitBuilder::<F, D>::new(config);
 
-        let g = Secp256K1::GENERATOR_AFFINE;
-        let g_target = builder.constant_affine_point(g);
-        let neg_g_target = builder.curve_neg(&g_target);
+        let msg = F::rand();
+        let msg_target = builder.constant(msg);
+        
+        let sk = ECDSASecretKey::<C>(Secp256K1Scalar::rand());
+        let pk = ECDSAPublicKey((CurveScalar(sk.0) * C::GENERATOR_PROJECTIVE).to_affine());
 
-        builder.curve_assert_valid(&g_target);
-        builder.curve_assert_valid(&neg_g_target);
+        let pk_target = ECDSAPublicKeyTarget(builder.constant_affine_point(pk.0));
+
+        let sig = sign_message(msg, sk);
+
+        let ECDSASignature { r, s } = sig;
+        let r_target = builder.constant_nonnative(r);
+        let s_target = builder.constant_nonnative(s);
+        let sig_target = ECDSASignatureTarget {
+            r: r_target,
+            s: s_target,
+        };
+
+        builder.verify_message(msg_target, sig_target, pk_target);
 
         let data = builder.build();
         let proof = data.prove(pw).unwrap();
 
         verify(proof, &data.verifier_only, &data.common)
-    }*/
+    }
 }