secp256k1_XMD:SHA-256_SSWU_RO_ missing the isogenous generator

arkworks-rs · Nov 4, 2024 · 2423caa · 2423caa
1 parent e107556
commit 2423caa
Showing 1 changed file with 54 additions and 0 deletions.
diff --git a/curves/secp256k1/src/curves/mod.rs b/curves/secp256k1/src/curves/mod.rs
@@ -1,4 +1,8 @@
 use ark_ec::{
+    hashing::curve_maps::{
+        swu::SWUConfig,
+        wb::{IsogenyMap, WBConfig},
+    },
     models::CurveConfig,
     short_weierstrass::{self as sw, SWCurveConfig},
 };
@@ -43,6 +47,56 @@ impl SWCurveConfig for Config {
     }
 }
 
+/// `secp256k1_XMD:SHA-256_SSWU_RO_` isogenous curve
+pub struct ConfigIsogenous {}
+impl CurveConfig for ConfigIsogenous {
+    type BaseField = <Config as CurveConfig>::BaseField;
+    type ScalarField = <Config as CurveConfig>::ScalarField;
+
+    const COFACTOR: &'static [u64] = Config::COFACTOR;
+    const COFACTOR_INV: Self::ScalarField = Config::COFACTOR_INV;
+}
+impl SWCurveConfig for ConfigIsogenous {
+    const COEFF_A: Self::BaseField = MontFp!("0x3f8731abdd661adca08a5558f0f5d272e953d363cb6f0e5d405447c01a444533");
+    const COEFF_B: Self::BaseField = MontFp!("1771");
+    const GENERATOR: sw::Affine<Self> = todo!();
+}
+impl SWUConfig for ConfigIsogenous {
+    const ZETA: Self::BaseField = MontFp!("-11");
+}
+
+// Parameters from the [IETF draft v16, section E.3](https://www.ietf.org/archive/id/draft-irtf-cfrg-hash-to-curve-16.html#name-suites-for-secp256k1).
+impl WBConfig for Config {
+    type IsogenousCurve = ConfigIsogenous;
+
+    const ISOGENY_MAP: IsogenyMap<'static, Self::IsogenousCurve, Self> = IsogenyMap {
+        x_map_numerator: &[
+            MontFp!("0x8e38e38e38e38e38e38e38e38e38e38e38e38e38e38e38e38e38e38daaaaa8c7"),
+            MontFp!("0x7d3d4c80bc321d5b9f315cea7fd44c5d595d2fc0bf63b92dfff1044f17c6581"),
+            MontFp!("0x534c328d23f234e6e2a413deca25caece4506144037c40314ecbd0b53d9dd262"),
+            MontFp!("0x8e38e38e38e38e38e38e38e38e38e38e38e38e38e38e38e38e38e38daaaaa88c"),
+        ],
+        x_map_denominator: &[
+            MontFp!("0xd35771193d94918a9ca34ccbb7b640dd86cd409542f8487d9fe6b745781eb49b"),
+            MontFp!("0xedadc6f64383dc1df7c4b2d51b54225406d36b641f5e41bbc52a56612a8c6d14"),
+            MontFp!("1"),
+            MontFp!("0"),
+        ],
+        y_map_numerator: &[
+            MontFp!("0x4bda12f684bda12f684bda12f684bda12f684bda12f684bda12f684b8e38e23c"),
+            MontFp!("0xc75e0c32d5cb7c0fa9d0a54b12a0a6d5647ab046d686da6fdffc90fc201d71a3"),
+            MontFp!("0x29a6194691f91a73715209ef6512e576722830a201be2018a765e85a9ecee931"),
+            MontFp!("0x2f684bda12f684bda12f684bda12f684bda12f684bda12f684bda12f38e38d84"),
+        ],
+        y_map_denominator: &[
+            MontFp!("0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffefffff93b"),
+            MontFp!("0x7a06534bb8bdb49fd5e9e6632722c2989467c1bfc8e8d978dfb425d2685c2573"),
+            MontFp!("0x6484aa716545ca2cf3a70c3fa8fe337e0a3d21162f0d6299a7bf8192bfd2a76f"),
+            MontFp!("1"),
+        ],
+    };
+}
+
 /// G_GENERATOR_X =
 /// 55066263022277343669578718895168534326250603453777594175500187360389116729240
 pub const G_GENERATOR_X: Fq =